Technical articles on enzymes

To achieve the fast growth potential, birds must endure a shift in energy metabolism and nutrient dynamics in post hatching birds have gastrointestinal tract that enhances rate of digestion enabling a fresh throughput of feed. Early intake of carbohydrates and water are required for conversion of energy metabolism , maturation of digestive tract and balance of other nutrients such as amino acids , minerals are required to optimization for subsequent performances towards profitability.

In this present time of microeconomics high rates of raw materials has lead to increase usage of enzymes in feed to get maximum out of feed.

Exogenous cocktail enzymes supplementation on diets improves production efficiency of poultry by increasing the digestion of low quality raw materials and reducing the nutrient loss through excreta , allowing the reduction of diet nutritional levels with likely more economic advantages . Multienzymes are added in to animal ration with the goal of increasing its digestibility , removing antinutritional factors , improving nutrient availability as well as for environmental issues.

A large numbers of complex carbohydrate degrading enzymes , proteases , phytases and lipases are used for this purpose. Usually well sourced cocktail enzymes used as additives do not contain a single enzyme , instead , there are optimal conjugation of enzymatic preparation containing variety of enzymes which are suitable and balanced to target specific substrates when generally ration are composed of different constitutions. Exogenous multienzymes hydrolyses non-starch polysaccharides ( NSPs ) which are potentially used by the animals , increasing the usage of feed energy . Moreover it renders the releasing of cell content , becoming available to enzymatic digestion , therefore increasing the digestibility of all the nutrients . Another important consequence of this utilization is the reduction of such non digestive residues which negatively impacts on intestinal digesta viscosity .

Economic Impact : Economic benefits from cocktail enzymes utilization on poultry nutrition is related to feeding cost reduction , allowing the better flexibilities on diet formulation and or a better performance and as well as better litter quality and birds health , which in turn influences total production costs in big way.

Flexibilization of low cost formulation : Availability and variety of grains of world are great which permits the total or partial inclusions and or substitutions of certain ingredients by others with reduced prices of ingradients mainly during the time between new harvests . However , such ingredients also named as alternatives and present some restrictions of their use in poultry diet formulation and it is due to the presence of anti nutritional factors that impair performance and consequently result in low uniformity , immunity and profitability at the end of production . Cocktail enzymes utilization allows these ingredients used as efficiently as Maize and Soybean meals do. As a example Xylanase and cellulase act by providing higher values of metabolizable energy resulting in greater weight gain and improvement in feed gain ratio as much as maize and soyabean meal can do.

There are different economic approaches when considering cocktail enzymes incorporation on diet formulation. A simpler and probably more practical application called Over The Top aims to improve performance more economically and suited for supplementation on standard diets with cocktail enzymes without altering its nutritional levels in present diet. Another alternative is to manipulate diet formulation by reducing nutrient levels and adding cocktail enzymes in order to restore the nutritional value of the same standard diet , seeking the same performance that a diet with normal nutritional levels would provide . If supplementation is efficient , substrate is enough and in right combination with cocktail enzyme preparation productive parameter would be same with a reduction of production cost . The possibility of using enzymes in reformulated diets must be evaluated in which the enzyme nutritional matrix is to be considered during diet formulation allowing a greater reduction on feeding costs , since cocktail enzyme preparation contribute with 60 to 100 M Cal ME by kilogram in ration which mainly depends on substrate available in the diet and units of individual enzyme present in the cocktail . And important indication of the effective feed utilization is the ration between feed intake and each kilogram of body weight. Consequently an economic evaluation of feed stuff used in diets can be simply attained through cost feeding by grain kilogram calculation . Evaluating the cocktail enzyme influence on broiler chicken performance , verified with that lower energy and proteins levels and supplemented with cocktail enzymes provided the broiler a similar performance of those fed diets with normal nutrient levels without affect performance and reducing cost consequently.

Higher nutrient,digestibility and better poultry performance : Nutrient digestibility can be improved with cocktail enzymes supplementation. A lot of scientists and researcher confirmed that an increase of AMEn of Maize and soybean based diets presented with low protein and energy. A group of scientist proved that the addition of appropriate units of Amylase , Cellualse , Xylanase ,Protease , Pectinase , Lipase , Glucanase in diets with 3 % of ME reduction for broiler chickens resulted in similar performances to the obtained with control diet.

Studies revealed that using diets formulated with overestimated values up to 9 % for ME and 7 % amino acids, supplemented with Multienzyme complecomplex showing ME and amino acids ( Meth , Meth + cys and Lys ) efficiency of utilization. It has been concluded that energetic and amino acid density reduction of diets based on maize and soybean meal , containing multienzymatic complex , do not compromise broiler performance and might be a resource on production costs reduction.

Improvement of Litter quality : NSPs increase diet viscosity due to its capacity of bonding to great amount of water and forming a viscous gel decreasing the rate of diffusion of substrates and digestive enzymes . In order to reduce digestive content viscosity it is necessary that soluble NSPs to be decomposed in small units through enzymatic actions and losing their water holding capacity with reduction in viscosity. Enzymatic action on intestinal content is more efficient and therefore , there is improvement on nutrient digestion capacity decrease on intestinal transit rate and reducing of water amount of feces , providing better quality thus improving environment of shed . This lead to less respiratory problems in and around .
Effect of multienzyme supplementation on broiler chicken diet on incidence reduction of pododermatitis in broilers verified lower visocisity of supplemented with birds digesta. Positive visocosity reduction with reduction on litter moisture , a lower incidence of wounds in older birds concluding that enzymatic supplementation of diets might be a tool aiding to control pododermatitis .

Improvement of Birds Health : Several studies show that the use of fiber degrading enzymes inhibits fermentation at the ileum and stimulates fermentation at cecae . Reduction of ileal fermentation is beneficial to the host , because most of the fermented material at this region constitutes of undigested starch and protein , which , thus become available for hydrolyses and adsorption by the host . Moreover oligosachharides resulting from NSPs degradation by cocktail enzymes are like to have prebiotic effect at cecae , acting as substrate for proliferation of beneficial bacteria , therefore improving birds overall health . There is necessity to evaluate over all performance of farm , consistency of performance.
Greater Production of Lactic acid at ileum and Propionate at the cecae with xylanse utilization of diets regarding protein cakes generally favors a better intestinal health in broilers due to bacteria which produce lactic acids and promotes a competitive exclusion and proionate is toxic to salmonella and other pathogeneic bacteria like E.coli.

Environmental impacts of cocktail enzymes utilization on Poultry Feeding : Environmental pollution is defined as contamination by Poisons , Substances produced by men , Production and other organisms . Researchers with enzymes demonstrated the importance of these substances to reduce the negative effect anti nutritional factors and improve feed efficiency . During the process of diet , nutrients convert into animal products , considerable losses occur even if animals are at ideal production conditions with quality feeding and appropriate management . It is possible to make use of several nutritional manipulation in order to reduce excretion and the most efficient measures include rations counter balancing in such way that attends more precisely to animal requirement , pure amino acid addition , reducing simultaneously the diet crude protein level and finally addition of substrate specific cocktail enzymes .

Birds are omnivorous animals and therefore they are not able to digest non – starch carbohydrates ( NSP ) as those present in soluble and insoluble manner . thus many vegetable ingredients usually used in Poultry diets present inferior digestibility values , when administered to birds in comparison to animal with superior fermentative capacity as swine . The improvement of digestive capacity through the use of supplementary cocktail enzymes is presented as serious alternative to not only improve performance but also as a mean to reduce excreta amount which decreases the contaminant potential of the production cycle which disturbs environmental balance Birds excrete more than more than half of nitrogen and phosphorus they consume . Cocktail enzymes and phytase used in poultry and other livestock animals diet improves digestibility and availability of certain nutrients for animal ,mainly phosphorus, nitrogen , calcium, copper and zinc , diminishing its presence on feces and urine and hence reducing its deposition to the environment . The hidden benefit from the use of cellulase , xylanase , pectinase and glucanase in birds fed viscous cereals include the reduction of excreta amount eliminated to the environment as well as the elimination of problems associated with loose droppings , larvae production , dirty eggs , elevated gas production and presence of flies and rodents in the facilities.

The use of enzymes as a feed additive has rapidly expanded during the past decade. Commercial enzymes commonly have fungal or bacterial origins. Enzymes are sensitive to environmental conditions and have the best performance at moderate temperature and 6-8 pH ranges. Early attempts regarding enzyme utilization date back to the early 1960’s, Studies particularly in the discipline of poultry nutrition have presented a very significant breakthrough in our knowledge of the science of nutrition.

In poultry gastrointestinal tract, the most important role of enzyme is to break the cell wall of diet nutrients and to make a uniform mixture of materials, which leads to increased digestibility of nutrients especially carbohydrates. Productions of amylase, lipase, pepsin and trypsin enzymes are maximized at 5, 7, 10 and 15 days of age respectively in the poultry gastrointestinal tract. The amount of amylase and protease enzymes produced is insufficient in the first few days of age. Wheat is a suitable energy source for poultry. The rate of addition of wheat in the poultry diet is limited to 20 percent with out supplementing enzymes. Barley is having more fiber and less starch compared to wheat. Barley’s ß-glucan and wheat's arabinoxylan as non-starch polysaccharides (NSP) are most important anti nutritional factors. The soluble NSPs impair the effect of endogenous enzymes and are known to give rise to highly viscous conditions in the small intestine that decreases the rate of digestion and absorption of nutrients in the diet.

Endosperm of cell wall consists of carbohydrates, protein and folic acid. Carbohydrate constitutes polysaccharides such as cellulose, hemi cellulose, pentosans and oligosaccharides such as rafinose and stachyose. Narrow fibers of cellulose surrounded by non cellulose polymers and glucan fibers contact with each other which makes carbohydrate non soluble and prevents enzymatic digestion. Cellulose present in endosperm cell wall is not nutritionally important. The main carbohydrates of these cells are hetero polymers such as ß-glucans and arabinoxylans. Both of these polymers are present in cereals but their proportion varies in the grains. For instance ß -glucans in barley and arabinoxylans in wheat are dominant. Breaking down of endosperm cell wall is very important for better digestion. Addition of enzymes in the feed helps to break the cell wall, which has an important role in optimum usage of starch present in cereals.

Research studies have revealed that water-soluble NSPs present in wheat and barley adversely affects the performance of poultry. Endogenous enzymes cannot hydrolyze soluble NSPs, pentosans and ß -glucans and result in poor feed conversion, reduced body weight gain and wet litter condition. Meanwhile, these compounds, which are present in grains such as wheat and barley, will interfere with the digestion of all nutrients in the diet, particularly fat, fat-soluble vitamins, starch and protein. Pentosanase and ß -glucanase are added to diets to counter the anti nutritive effects of pentosans and ß -glucans. Enzymatic digestion of NSP improves performance and allows more efficient use of nutrients. The use of enzymes in wheat-barley fed birds to reduce intestinal viscosity is likely to be the most effective method for improving performance. Supplementing diets with enzymes can enhance the physiological process of digestion and absorption of the nutrients, which is not available to poultry.

At present, enzyme supplements are used extensively in wheat and barley based poultry diets and a lot has been discovered on use of enzymes in poultry nutrition. In recent years, poultry nutritionists found that levels of wheat and barley in poultry diets can be increased with enzyme supplementation. Enzyme supplementation helps to increase digestibility, decrease the cost of diet, feed conversion rate, improves chemical condition of litter, and decreases organic wastes.

Yousefpour et al.(2001) compared performance of broiler fed diets with increasing amounts of wheat and barley supplemented with enzymes under farm conditions. Experiment was conducted in order to compare the effect of two levels of wheat and barley with or without multi enzyme supplementation with corn-soy control diet on broiler performance. Chicks were obtained from a commercial hatchery and in a completely randomized design (CRD) experiment, 6 treatments with 5 replicates were used and 25 chicks were placed in each of floor pens. At each with or without multienzyme cases, two levels of wheat and barley were used including 10, 35 and 60 percentage of wheat and barley as level 1 diets and 25, 55 and 80 percentage as level 2 diets for starter, grower and finisher periods respectively. There was also a corn-soy diet with no enzyme addition as control for all periods of rearing. The weight of each pen was determined on 1st , 21st ,42nd and 47th days. Feed consumption, body weight gain, feed conversion ratio and mortality were recorded when chicks were 21, 42 and 47 days of age.

The above study demonstrated that wheat/barley-containing diets supplemented with multi enzyme, increased weight gain in broilers compared to non-enzyme diets and the birds that fed high level of wheat/barley supplemented with multi enzyme had better performance compared to control diet. These results showed that broilers increased feed intake in order to energy and nutrients deficiency. In the first 21 days of the experiment, the groups that fed wheat/barley supplemented enzyme diets had better feed conversion ratios.

These findings showed that, young birds are unable to digest non-starch polysaccharides. Enzymatic digestion of NSPs improves performance and allows more efficient use of nutrients. At 47 days, feed conversion ratio in high level wheat/barley diet with no enzyme was more than control, but enzyme supplemented diet had better FCR, compared to control. Feed conversion ratio of different experimental groups had no significant differences in the last phase of feeding. This finding expressed that gastrointestinal enzymes developed in this phase of age and broiler can better digest the wheat and barley present in the diet. Briefly, enzyme supplementation can improve performance in broilers that fed diets with high levels of wheat and barley, with none of the litter problems associated with feeding such grains.

The use of enzymes as a feed additive has rapidly expanded during the past decade. Enzymes as additives to animal feedstuff have had a great impact on the livestock industry. Enzymes not only improved the utilization of diets containing cereals such as barley, wheat, rye and oats, especially for poultry, but also have had a positive impact on the quality of the environment through reduced output of excreta and pollutants such as phosphate and nitrogen including ammonia.

Nonstarch polysaccharides (NSPs) have an antinutritive activity, which is manifested by wet droppings and poor use of nutrients. Microbial enzymes targeting these polymers have, for this reason, shown highly positive results in both enhancement of performance and reduction of excreta volume and moisture.

Dry-Matter Digestibility (DMD) in animals ranges from 50 to 80%; the remainder of the Dry Matter (DM) is lost via the excreta. Excretion of large amounts of organic matter, especially organic matter containing high levels of nitrogen and phosphorus, preents serious environmental problems. The effect of enzyme supplementation of DMD in pigs and poultry depends on the type of diet and the type of animal.

A decreased output of Organic Matter (OM) to the environment is an important attribute of feed enzymes because excessive output of nitrogen and phosphorus is a major problem in densely populated areas. It is found that, the enzyme supplementation improved DMD by 17%, Apparent Metabolizable Energy (AME) by 24%, and Feed-Conversion Rate (FCR) by 31%, which coincided with a 50% reduction in digesta viscosity (Table 1)

Table 1. Effect of enzymes on DMD, AME, FCR, and digesta viscosity in broilers fed low-ME and normal wheat diets (n=8)
Diet	DMD (%)	AME(MJ/kg DM)	FCR	Viscosity (Mpa.s)
Maize control	81.0	16.6	1.96	3.2
Low-ME wheat	65.2	12.0	2.69	20.3
Low-ME wheat + enzymes	76.3	14.9	2.05	10.4
Normal Wheat	74.9	14.5	2.01	9.7
Normal wheat + enzymes	76.6	14.8	1.95	5.7

Note : AME : Apparent Metabolizable Energy, DM: Dry Matter, DMD: Dry-mater digestibility, FCR : Feed conversion Rate, ME: Metabolizable Energy.

Elevated levels of intact soluble NSPs detrimentally increased the activity of fermentative micro-organisms in the small intestine. Xylanase supplementation largely eliminated fermentation in the small intestine and improved the performance of the birds. Morgan and Bedford (1995) reported that using enzymes could prevent coccidiosis problems. Birds fed a wheat-based diet with and without glycanase supplementation showed vastly different responses to coccidiosis challenge.

Enzymes also allow the use of a wide range of ingredients without compromising bird performance and hence provide great flexibility in least-cost feed formulation. Enzymes also allow a wide range of ingredients to be used in a diet for a desired outcome. this give the producer a great deal of flexibility in formulating a nutritionally balanced, least-cost diet. The nutritive value of cereal grains for producer for poultry varies greatly and this problem can be largely overcome by using glycanases to bring the apparent metabolizable energy of different whats to comparable levels.

The use of enzymes as a dietary supplement has had a dramatic effect on the utilization of certain feedstuffs in animal husbandry, particulary in poultry and especially with those diets that contain cereals such as barley and wheat. Future Research and Development will continue to be supported on an ever-increasing level by industry in an ever-widening field. Some of the future areas of emphasis will be :

1. as expanded range of use of enzymes in the diets of poultry and domestic livestock including classes of poultry other than chickens, pigs, fish and exotic animals such as alligators and turtles.

2. Alternate sources of genetically engineered enzymes designed for the particular target substrate and animal by recombinant DNA technology.

3. Greater emphasis of other benefits of enzymes such as their effect on reducing pollution, partitioning of nutrients and altering the endocrine response and health status of the animal.

Author : Dr. Sudhir Kumar Rathor, Dept. of Animal Nutrition, College of Vety. Science & Animal Husbandry, Mathura

The present study was undertaken to find out the effect of multienzyme supplementation on the performance of broiler chickens, viz. growth, feed intake, feed gain ratio and metabolizability of nutrients. The effect of experimental diet on carcass paramenters was also investigated.

150 day old commercial broiler chicks were randomly distributed to 5 dietary treatment groups consisting of 30 birds in each group. Similar managemental conditions were maintain for all the birds during the period of seven weeks. Diet (T₁) was computed as per BIS (1992) to meet out metabolizable energy, crude protein and limiting amino acid (lysine and methonine) requirement of birds to serve as control. Enzyme supplemented diets i.e. T₂ (T₁+multienzyme @ 25 gm/100 kg feed), T₃ (T₁+multienzyme @ 50 gm/100 kg feed), T₄ (T₁+multienzyme@ 75gm / 100 kg feed), T₅ (T₁+multienzyme@100 gm / kg feed) were formulated by adding commercial multienzyme.

The average body weight gain and average feed intake per bird were recorded weekly and feed gain ratios were calculated for all treatments for different growth periods. Two metabolic trials were conducted first at the age of 4^th week and 2^nd at the age of 7^th week for the evaluation of digestibilities of dry matter, other extract, crude fiber, nitrogen free extract and retention of nitrogen, calcium and phosphorus. 4 birds per treatment were sacrificed at 7th week of age to study carcass parameters.

At the 3rd day (beginning of experiment), the average live weight of chicks was 73.66 gm. The body weight gain during all periods of growth was maximum in group T₃ in which multienzyme was mixed @ 50 gm / 100 kg of feed; followed by T₂, T₄, T₅ and T₁. However, body weight was statistically similar in all the treatment groups. Total body weight gain in overall growth period was 2227.66 gm in T₃, 2222.96 gm in T₂, 2164.98 in T₄, 2152.98 gm in T₅ and 2020.27 gm in control.

Enzyme supplementation increased body weight gain in all 4 groups in contrast to control group. However, the differences were non significant in all the groups.

The feed intake was statistically similar during entire experimental period in all the groups. Enzyme supplementation diet showed non significant increased in feed consumption than control.

Feed consumption was maximum in T₃ group followed by T₄, T₂, T₅ and T₁.

Total feed consumption in seven weeks in T₁, T₂, T₃, T₄, T₅ was 5058.52 gm, 5048.70 gm, 5041.30 gm, 5007.10 gm respectively.

There was a significant improvement in FCR, during the overall growth period with enzyme supplementation. Improvement in FCR was statistically similar in T₂, T₃and T₄ while improvement in FCR of T₅ groups was in between with these 3 groups (T₂, T₃ and T₄) and control (T₁). The overall, FCR of T₁, T₂, T₃, T₄, T₅ were 2.38, 2.22, 2.19, 2.25, 2.29 respectively.

Dry matter metabolizability was significantly higher in enzyme supplemented groups during overall growth period.

Enzyme supplementation also increased the digestibility of the ether extract, crude fiber and nitrogen free extract than control though the difference were non significant. Overall digestibility of organic nutrients were as follows.

Overall D.M. digestibility for T₁, T₂, T₃, T₄, T₅ were 75.01%, 76.86%, 77.85%, 76.36%, 76.05% during 1st metabolic trial while during 2^nd metabolic trial these were found to be 71.05%, 71.19%, 73.75%, 72.67%, 72.65% respectively.

Overall ether extract digestibility in % for T₁, T₂, T₃, T₄, T₅ were 93.73%, 95.50%, 96.20%, 94.42%, 96.10% during 1st metabolic trial while during 2^ndmetabolic trial these were 88.99%, 89.48%, 91.23%, 90.22%, 90.29% respectively.

Overall nitrogen free extract digestibility for T₁, T₂, T₃, T₄, T₅ were 90.02%, 90.07%, 90.12%, 90.22% during 1st metabolic trial while during 2^nd metabolic trial these were 89.74%, 90.62%, 92.66%, 91.28%, 90.97% respectively.

Overall crude fiber digestibility for T₁, T₂, T₃, T₄, T₅ were 38.60%, 39.50%, 40.32%, 39.02%, 38.49% during 1st metabolic trial while during 2nd metabolic trial these were 33.49%, 34.14%, 36.10%, 35.16%, 35.24% respectively.

Overall retention of nitrogen in gm / day for T₁, T₂, T₃, T₄, T₅ was 3.81, 3.89, 4.05, 3.91, 3.98 while during 2nd metabolic trial these were 4.72, 4.80, 4.97, 4.85, 4.79 respectively.

Overall retention of calcium in gm / day for T₁, T₂, T₃, T₄, T₅ was 1.19, 1.30, 1.38, 1.29, 1.34 during 2nd metabolic trial there were 4.72, 4.80, 4.97, 4.85, 4.79 respectively.

Overall retention of phosphorus in gm / day for T₁, T₂, T₃, T₄, T₅ was 0.69, 0.71, 0.91, 0.72, 0.71 during 1st metabolic trial while during 2^nd metabolic trial this was 0.78, 0.81, 0.92, 0.87, 0.90 respectively.

Enzyme supplementation resulted in significant improvement in nitrogen, calcium and phosphorus retention than control.

Average live weights and shrinkage weight were higher in enzyme supplemented groups than control however the differences were non significant.

No definite trend was observed in average defeathered and deskined and average evisceration weight in enzyme supplemented or unsupplemented group.

No definite trend was also observed in shrinkage loss, debleeding, defeathering and deskined loss, evisceration loss in enzyme supplemented or unsupplemented groups.

Dressing % increased in enzyme supplemented diets. Dressing % was highest in T3 group while lowest in control group. In other group the dressing % was in between T3 and control group. However, the differences were non significant.

The overall dressing % of T1, T2, T3, T4, T5 groups were 68.92%, 69.92%, 70.10%, 68.78% and 69.63% respectively.

Giblet yield and leg piece yield was found to be more in enzyme supplemented group. Highest giblet and leg piece yield was achieved in treatment T3. However, the differences were non significant. In other group Giblet yield and leg piece yield was in between control and T3.

RESULT : From the experiment with small number of broilers, it was found that a definite level of multienzyme i.e. 50 gm / 100 kg of feed was more beneficial than other levels as this level has significantly effect on FCR.

I. Enzyme Supplementation To Improve The Productive Value Of High Fibre Diets

Studies conducted on the effect of in vitro digestion on the chemical composition of broiler feed incorporated with enzymes suggest an increase in available carbohydrate (A-CHO) and acid soluble nitrogen fraction (ANSF) and reduction in acid detergent fibre (ADF) and neutral detergent fibre (NDF) of low fibre (LF) and high fibre diets supplemented with 1.0 and 1.5 g/kg enzyme feed supplement (EFS). One gram of EFS contained amylase, 7,500 units; cellulase, 400 units; protease, 200 units and lipase, 300 units. LF and HF diets contained un-autoclaved and autoclaved rice bran (RB), wheat bran (WB) and sunflower cake (SC). The observations have also been supported by in vivo studies. These studies involved two types of diets namely LF (fibre, 3.2%) and HF (fibre, 6.4%) containing 22.18% crude protein; 2900 kcal ME and 22.68% crude protein; 2600 kcal/kg ME, respectively. Third diet (HF1) had 1.5-g/kg enzyme feed supplement. LF diet contained autoclaved rice bran (RB) as higher fibre feed ingredient whereas HF diet contained autoclaved RB, wheat bran and sunflower cake as high fibre feed ingredients. Body weight gain, feed efficiency and performance index were significantly higher in chicks fed diet with EFs. Cost of production of 1 kg live weight of broiler fed LF diet was Rs.13.68, whereas for producing the same live weight gain of broiler fed HF diet with EFS, the cost involved was Rs.13.56. Therefore, in the production of 1 kg live weight in broiler fed HF diet with EFs, there was saving of 12 paisa approximately. It was also suggested that for large-scale broiler production, use of autoclaved high fibre ingredients along with EFs was economical. The cost benefit analysis at 6 weeks of age is given below:

II. Effect of non-starch polysaccharide hydrolyzing enzymes (cellulase, xylanase, pectinase and a-galactosidase etc.) on performance of broiler fed maize-soya diets.

Experiments on utilization of non-starch polysaccharides (NSP) indicated that the performance of broilers in terms of weight gain, efficiency of feed utilization, livability and carcass attributes is not affected by supplementation of different NSP degrading enzymes. The supplemental levels of enzymes incorporated individually or in combination were as follows.

The insignificant effect of enzyme supplementation on performance indicates that the enzymes at the concentration used did not elicit any beneficial response on the utilization of NSP in broilers. The calculated total NSP content in starter and finisher diets is 9.79 and 9.58%, respectively, out of which the major component is glucose, which might be a monomer of cellulose. The observed significant increase in weight gain in xylanase and pectinase fed birds at 28 d of age and subsequent disappearance of this effect in these experiments indicate that the chicken at the younger age are not able to utilize xylans and pectins and thus required additional supplementation of enzymes to hydrolyze these compounds. This observation also indicates that as the age of the bird advances the anti-nutritive effect of these NSP declines.

The growth depression observed in broilers fed xylanase + pectinase + alpha-galactosidase might be due to incomplete hydrolysis of the NSP and consequent increased viscosity of intestinal digesta. The alpha-galactosidase concentration employed was very low. The increased viscosity of intestinal digesta is known to inhibit the digestion and subsequent absorption of nutrients from the feed. The growth depressing effect of above enzymes on broilers was alleviated by the addition of cellulase to the above enzyme complex. Since, cellulose is the major component of the NSP in the experimental diets, cellulase supplementation might have increased the hydrolysis of ß-1-4 linkage of glucose monomers utilization in broilers fed a combination of xylanase + pectinase +
alpha-galactosidase + cellulase. It is also possible that on breakdown of cellulose, the major component of the cell wall the release of encapsulated intracellular nutrients might have been released.

Several workers also did not observe any significant effect on broiler performance due to supplementation to corn soya diet of either individual or multi-enzymes hydrolyzing NSPs. Contrary to this, a significant improvement in broiler performance has been reported in broilers when fed either corn soya diet or soyabean meal supplemented with either individual or combination of NSP hydrolyzing enzymes. The reported beneficial effects of NSP enzymes on broiler performance may be due to increase in digestibility and retention of nitrogen, increase in dry matter and energy utilization. The reported wide variation in the performance of broilers due to NSP enzymes supplementation to corn soya diet might be due to variations in the concentration and composition of NSP in the diet and source and/or activity of the enzymes supplemented. The activity of a specific enzyme produced even from the same microorganism vary significantly. Further, the variation could also be due to the variation in dose and composition of enzyme cocktail. The improvement in broiler performance observed by some workers due to supplementation of enzyme could be due to incorporation of higher dose of cellulase (1000 to 3000 IU/kg diet) compared to the levels used in some of other studies (420 and 560 IU/kg diet) and also be earlier workers (15 to 97 IU/kg diet). The lack of response due to supplementation of only xylanase in corn-soya is expected because, the monomers released from by the action of the enzyme on arabinoxylan i.e. arabinose and xylose are poorly metabolized by poultry and therefore of little value to animal performance. The addition of a mixture of enzymes considering the composition of NSP in a given diet may yield better response compared to supplementation of individual exogenous enzyme. A series of experiments have also been conducted in CARI Experimental Station employing various maize-soya, pearl millet, sorghum, finger millet, mustard cake and un-decorticated sunflower seed meal based diets in broiler chickens, native chickens and Japanese quails. The commercial preparation was analyzed and found to contain sufficient enzyme activities. The enzyme preparation was incorporated in diet at level of 50-g/100 kg. The activities of various enzymes in a gram of commercial enzyme preparation were: ß glucanase, 35732; ß-D xylanopyrosidase, 98466; xylanase, 2202; FT Pase, 397; amylase, 5773 and CM cellulase, 1906 MIU/kg. There was marginal improvement in growth of broiler chicks in pearl millet based diets during starting phase while significant improvement was observed in finger millet based broiler starting and finishing diets. Enzyme supplemented was also found beneficial to improve utilization of sunflower seed meal supplemented in maize-finger millet or maize-sorghum based broiler starting and finishing diets. However, on repeated trials on maize-soya-deoiled rice bran diets for three times in broiler chickens, twice in Japanese quails and twice in native chickens, enzyme supplementation did not prove beneficial in terms of growth or feed conversion efficiency.

Some of the reports on enzyme supplementation and its effect have been summarized hereunder:

III. In vitro evaluation of non-starch polysaccharide digestibility of feed ingredients by enzymes:

Some of the commonly used feed ingredients for poultry (corn, sorghum, finger millet, deoiled rice bran, soya bean meal, peanut meal, sunflower meal and rapeseed meal) were screened for pentosans, cellulose, pectin and total non-starch polysaccharides. The ingredient in vitro digestibilities by enzymes were evaluated. Cereal samples screened contained mainly pentosans. Pectin content was rich in oilseed meals. Sunflower meal, soybean meal, deoiled rice bran and a broiler starter diet were subjected to a 2 stage in vitro digestion assay with 3 different enzyme mixtures viz. Enzyme-I (xylanase + cellulase from Trichoderma viridae), Enzyme-II (xylanase + Cellulase + beta-glucanase from Huminicola insolens) and Enzyme-III (xylanase + cellulase + pectinase + beta-glucanase from Aspergillus aculeatus) by incubating 0.1 g of the sample with 3 ml of a pepsin-HCl mixture (2000 U pepsin/ml of 0.1 N HCl) for 45 min to simulate the peptic phase of bird digestion. A panereatin-NaHCO3 mixture (2 mg panereatin/ml of 1 M NaHCO3) was used for 2 h at 40°C to simulate the panereatic phase. Digestibility was assessed by measuring the relative viscosity of the digesta supernatant and the total sugars released. Enzyme-I produced the least relative viscosity and highest total sugars in sunflower meal, deoiled rice bran and broiler starter diet, and whereas, Enzyme-III was very effective in soyabean meal subjected to in vitro digestion.

Enzymes have been used in the feed industry for more than 30 years. Traditional applications have included improving the digestibility and bird performance of ingredients such as barley and wheat. As our understanding of the anti-nutritive factors that are associated with these and other feedstuffs has expanded, the applications for enzymes have also increased. Non-starch polysaccharides (NSP) can increase the viscosity of the digesta which can, in turn, decrease nutrient availability and animal performance. NSP are also linked to other compounds such as peptides and proteins that can make the use of a purified enzyme designed to degrade NSP less effective than lower rates of NSP degrading enzyme combined with other enzymes such as proteases. Other anti-nutritional factors such as phytate can also adversely affect performance and the use of phytase enzyme has been shown to improve phosphorus utilization as well as cation minerals and protein.

Other enzyme applications include feedstuffs such as corn and soy which have historically not responded to enzyme use. Recent enzyme formulations have proven effective in corn/soy diets for poultry as well as other species. Other studies have examined the stability of enzymes to heat and pressures associated with feed processing and found beneficial responses to enzyme supplementation even at pelleting temperatures of 90oC.

At the most basic level, feedstuffs consist of protein, starch, fat and fiber. In monogastric animals the fiber component has been considered to be wasted and in some instances, compounds called Non-starch polysaccharides (NSP) can exert anti-nutritive activity on the animal. The NSP of barley, wheat and rye has been the most intensively investigated. Beta glucan in concentrations ranging from 30-60 g/kg dry matter has been shown to depress production in broilers and cause sticky droppings (pasted vents). Wheat and rye contain relatively high levels of arabinoxylans or pentosans (50-80 g/kg dry matter for wheat; 100 g/kg dry matter for rye) which can also have a negative effect on broiler performance (Choct and Annison, 1990; Fengler and Marquardt, 1988). Ingestion of NSP by monogastrics results in increased viscosity of the digesta (Burnett, 1966; Antoniou and Marquardt, 1983). This increased viscosity reduces the passage rate of the feed leading to overall reductions in consumption and decreased performance, sticky droppings and dirty eggs (Classen and Bedford, 1991). The addition of enzymes to the diet to address NSP viscosity can improve feed efficiency, improve manure quality and increase the use of lower cost feed ingredients. Animal feed protein sources also have been shown to contain anti-nutritive factors which are listed in table 1.

The use of enzymes in animal feeds is becoming more common. Reasons for this include lower costs of commercial enzyme preparations, improved enzymes for animal feeds, and a better understanding of the composition of the anti-nutritive compounds. In order to obtain maximal benefits from enzyme inclusion in animal feeds, it is necessary to ensure that the enzymes are chosen on the basis of the feed composition. Simply put; the enzyme must be matched to the substrate. Enzyme cocktails containing more than one enzyme will often improve the response compared to pure, single enzymes, assuming that cost considerations are not ignored. This is due to the fact that feedstuffs are complex compounds containing protein, fat, fiber and other complex carbohydrates. Merely targeting a specific substrate such as Beta glucan may not provide maximal benefits since layers of other substrates may inherently protect some of the Beta glucan. For example, Beta glucans and arabinoxylans may be bound to peptide or protein moieties in the cell wall of the feedstuff. Therefore, enzymes capable of hydrolyzing protein may enhance the activity of pentosanases and beta glucanases. Methods commonly used to determine the effects of enzymes on feedstuffs include determination of the NSP content of the ingredients or by measuring changes in the viscosity of the feed with enzyme supplementation.

Beta glucanase was one of the first enzymes used extensively in the feed industry. Dietary supplementation of barley with b -glucanase allows the inclusion of higher levels of barley to be used by hydrolyzing the b -glucan chains. This leads to a less viscous digesta and allows better nutrient utilization. Numerous studies confirm the efficacy of such enzymes when used in barley-based diets in poultry. One such trial examines a dose titration of a commercial b -glucanase (table 2). From this data it can be observed that maximal response was noted when 300 units/kg b -glucanase was used.

Table 2 : Effect of b -glucanase on broiler performance fed a barley-based diet (to 39 days). Diet contains 50% barley containing 4.3% b -glucan.

Wheat, rye and triticale contain a relatively high concentration of non-starch polysaccharide consisting mainly of arabinoxylans and some beta glucans. In order to overcome the adverse effects of arabinoxylans, a different enzyme must be used. Pentosanase (or xylanase) can overcome the deleterious effects of these NSP by aiding in the breakdown of the arabinoxylans. The beneficial effects of pentosanases in wheat-based rations are most noticeable in young birds as shown in table 3. From these results, it is evident that improvements in daily gain and feed efficiency can be obtained from proper enzyme inclusion.

Table 3 : Effect of pentosanase on broiler chicks fed a wheat-based diet (to 21 days).

Legume seeds such as soy contain NSP in the form of oligosaccharides, hemicellulose and pectin. Alpha galactosides are raffinose- and stachyose-based oligosaccharides that accumulate as the seed matures. Endogenous enzymes in monogastrics are specific for alpha-linked carbohydrates such as starch but have little or no effect on beta linked carbohydrates or galactose-containing oligosaccharides. Degradation of these galactosides is accomplished by the gut microflora yielding volatile fatty acids and gas production. The net result is less energy and gastric disturbances in many species. Enzymatic degradation of these compounds can produce monosaccharides and result in better energy and protein utilization. In poultry, improvements in gain and feed conversion have been noticed with an enzyme cocktail formulated for corn-soy diets (table 4). Although not shown in the table a dose titration yielded maximal response at a use rate equivalent to 3750 HUT/kg (protease) and 37.5 CMC/kg of feed (De Koning personal communication). Amino acid digestibility has also been improved with this enzyme (Pugh and Charlton, 1995; table 5).

Table 4 : Effect of a soy-specific enzyme cocktail containing protease (7,500 HUT/g) and cellulase (75 CMC/g) on broilers fed a wheat, soy diet.

Table 5 : Effect of a soy-specific enzyme cocktail containing protease (7,500 HUT/g) and cellulase (75 CMC/g) on true amino acid digestibility (%) of soybean meal (48%).

Other corn / soy enzyme cocktails yield similar results. Zanella and coworkers (1999) found that an enzyme formulation containing protease (6,000 u/g), amylase (2,000 u/g), and xylanase (800 u/g) resulted in a 2.9% improvement in total protein digestibility and improvements in gain of approximately 50-g/bird, and feed conversion (about 4 points better with enzyme supplementation). Because of the improvements observed in protein digestibility it is tempting for the nutritionist to lower the overall protein and energy levels of the diet. However, because of the variation in individual amino acid digestibility, caution is advised in doing this in order to ensure adequate levels of limiting amino acids.

PHYTASE

The benefits of phytase have been known since the 1960s and a large number of studies have proven efficacy in poultry diets to lower the overall added inorganic phosphorus levels. This is due to the ability of the enzyme to degrade phytate phosphorus found in feedstuffs. Phytate has the ability to complex with protein, peptides or cations including calcium, magnesium, copper, zinc and iron. These compounds when complexed to phytate are less available and digestible. In addition, Singh and Krikorian (1982) found that phytate could also bind endogenous enzymes such as chymotrypsin and trypsin in the GI tract which could further inhibit protein digestibility. Supplemental phytase enzyme can therefore improve the availability of phosphorus, other minerals and improve digestibility of protein. Lowered costs of phytase production have allowed widespread use of the enzyme which was previously only used because of government mandates on lowering phosphorus emissions from livestock areas. Until recently phytase seemed like an oxymoron for the environmentalist. This is due to the fact that the predominant commercial phytase is derived from a genetically modified organism (GMO). However, current technologies in solid-state fermentation and traditional microorganism strain improvements have yielded non-GMO sources for this enzyme. Comparisons of GMO and non-GMO phytase sources have yielded similar results (Rowland et al., 2000; Sims et al., 1999) and led to a more competitive and lower cost phytase product. Additionally, recent studies have shown improvements in areas of nutrient utilization other than simply phosphorus and calcium absorption increasing the benefit to the producer (Namkung and Leeson, 1999).

Microorganisms in the gastrointestinal tract utilize the digesta for energy in a similar manner to the host animal. Changes in rate of passage and the type of nutrients available to the microbes influence the different microbial populations in the GI tract. The end products of metabolism of many of the anaerobic bacteria found in the gut are volatile fatty acids which have been shown to be altered with enzyme supplementation (Choct, 1995). However, studies examining differences in specific microbial populations such as starch or xylan- degrading bacteria have yielded no significant effects (Persia, et al., 1999). This may be due to lack of technology to adequately examine these populations since it stands to reason that as the substrate changes so should the microorganisms that can use them. Gastrointestinal histology has also been shown to be affected by barley and wheat-based diets with reductions in villi height, increased diameter and damaged villi associated with wheat and barley diets (Viveros et al., 1994; Jaroni et al., 1999). Enzyme supplementation of these diets counteracted some of these effects with supplemented birds having a gut morphology more similar to birds receiving a corn/soy diet. This may also help explain reductions in mortality that is often seen in birds receiving enzyme supplementation. Damage to the GI tract may make the organ more susceptible to pathogenic bacterial invasion. In addition, enzyme supplemented birds had lower gut and pancreas weights. The strain of bird used also had a bearing on these results.

Since enzymes are proteins, the structure of the enzyme is critical to its activity. PH, heat or certain organic solvents can alter enzyme structure. Changes in the structure of the protein can decrease or negate enzyme activity. The temperatures which feeds are exposed during the pelleting process can range from 60 to 90oC under normal conditions. These temperatures and pressures can therefore lead to loss of feed-borne and added enzyme activity (Rexen, 1981). Recent studies reveal that enzyme activity begins to decrease as pelleting temperatures reach 80oC. These data suggests that cellulase, fungal amylase, and pentosanase can be pelleted at temperatures up to 80oC and bacterial amylase up to 90oC without any considerable loss of activity (Spring et al., 1996). However, caution must be used in interpreting these data since substrates necessary for in-feed assay of enzyme activity may not reflect the actual components of the feed. In the case of cellulase activity, in vitro substrate activity was significantly diminished at 80oC while the viscosity of the feed was improved even at temperatures up to 90oC. Therefore, for the feed manufacturer, practical enzyme activity of cellulase was maintained up to 90oC. Subsequent work by Samarasinghe et al. demonstrates that, although cellulase activity found in the feed after pelleting at 90oC was reduced by 73%, the average growth rate of broilers increased by 11% when feed containing the enzyme was compared to feed with no enzyme (Samarasinghe et al., 2000). At first glance these results seem confusing. However, studies have shown that the viscosity of the feed increases with increasing pelleting temperatures (Nissinen, 1994; Spring et al., 1995; Vukic-Vranjes and Wenk, 1995). This is due to starch gelatinization and increased solubilization of fiber. The viscosity of feed pelleted a high temperatures has been shown to be negated by inclusion of enzymes in the feed prior to pelleting. In fact, enzyme inclusion lowered the extract viscosity of the feed by 11, 14 and 17% at 60, 75 and 90oC respectively compared to feed without enzyme inclusion (Samarasinghe et al., 2000). With this data in mind, it becomes apparent that one mechanism of enzymes may not be in the bird at all but rather the activity of the enzyme during the pelleting process which exposes the enzyme to moisture and heat giving the possibility of optimal conditions for enzyme activity prior to it’s inactivation by the excessive heat. In cases where temperatures are excessive for enzyme stability, post-pelleting application is commonly used.

CONCLUSIONS

Numerous studies over the past ten years have demonstrated improvements in feed utilization with enzyme supplementation. Use of b -glucanases in barley diets and pentosanases in feed ingredients high in NSP is now common practice. Reduction in viscosity of the digesta may enhance nutrient utilization by the bird by "normalizing" the histology of the gut when NSP diets are fed. Evidence also exists that enzyme cocktails containing proteases may enhance the beneficial effects associated with these enzymes. As enzyme technology improves we have also seen benefits in areas not traditionally associated with digestive inefficiencies such as energy and protein utilization from soy and other feed ingredients. Tradition tells us that the use of enzymes in corn/soy diets is not efficacious. However, recent advances indicate that this is not the case.

Future developments in enzyme technology will likely focus on more thermo-tolerant enzyme preparations, greater enzyme activity and enzymes which function optimally at low gastric pH values. Additionally, as more is known of the chemical nature of our feed ingredients, better methods of degrading these compounds may be found. In reporting studies on enzyme efficacy it is becoming increasingly important to ensure that the units of activity of the enzyme, as well as the use rate, be reported to improve our understanding of efficacy. Commercial enzymes can come from a variety of source microorganisms. The organisms produce enzymes that may have different pH and temperature optima. Because of this, different enzyme manufacturers may use other units of activity to describe an enzyme.

Author : Dr. D. Chandrasekaran, Prof. and Head, Dept. of Animal Nutrition, Veterinary College and Research Institute, Tamilnadu Veterinary and Animal Sciences University, Namakkal

The growth of the broiler industry is in geometric proportion. The per capita consumption of chicken meat in India has risen from mere 500gms to nearly 1.5kgs and it is expected to rise year by year. The performance in the broiler sector is improving year by year, the 42nd day body weight has reached nearly 2.4kg from 1.8kg in the nineties and the FCR has come down to 1.75 from 1.95 and the average mortality at present is well below 5%. This indicates the farmers are working to achieve set targets adopting modern technologies. Further, major changes have been observed in the consumer preferences, fatty carcasses are not preferred, they choose birds with higher dressing percentage and expect increased breast meat yield.

Achieving the target body weight with the best FCR is important, for which we have to work out a suitable strategy. The following points given below will help in planning an efficient strategy.

1. Growth Pattern
2. Intestinal development
3. Secretion
4. First feeding
5. Exploiting compensatory growth
6. Dietary manipulation

The mean body weight achieved at different ages and the energy deposited per kg gain is given in Table 1

Table 1. The body weight and the calorie conversion efficiency of the broiler (Hubbard manual)

At present efficient strains are there achieving even better body weights, the point to be considered is that the energy needed to achieve per kg gain is increasing week by week. The energy needed in the sixth week is nearly double of that needed in the first week, indicating more gain as fat as age advances. Further, the partitioning of energy between maintenance and growth was 20:80, 30:70, 40:60, 50:50, 60:40, 70:30 during 1st, 2nd, 3rd, 4th, 5th and 6th weeks respectively (Leeson and Summers,2005). When the protein turnover in the breast muscle (Table 2) was studied it was found that the protein gain was 68% 7th day, 52% on the 14th day, 47% on the 28th day, but it was only 23% on the 42nd day.

Taking into consideration the increment in the energy need for gain as the age advances and the decrease in efficiency of protein accretion, planning to achieve accelerated growth from day one and reach the target body weight at an earlier age will help in achieving a better FCR. To start challenging the chicks from day one, understanding the intestinal development and the gut secretions will be helpful. The weight of the intestine as a percentage of the body weight given in fig.1 indicates that by the 4th day the intestinal weight reaches a higher percentage comparable to the adult, further, reports state that the differentiation of the villi is achieved by 72h post hatch. The secretion of the enzymes trypsin, amylase and lipase (fig.2) indicates that sufficient quantity is secreted even on the 4th day itself, but the quantity of bile acid secreted on the 4th day is low compared to subsequent days, hence substitution of emulsifiers may be more advantageous than enzymes.

It has been observed that early feeding of the chicks hastens the development of the intestines (Fig.4) and consequently the increased 40th day body weight (Fig.5). This is supporting the fact that the yolk nutrients are to be used for body building and not to support the initial energy needs of the broiler. Based on the fact that accelerated development of the intestines and villi takes place in the first four days, feeding the chicks with highly digestible and absorbable nutrients provides a better start and helps in achieving a higher body weight (Table 3)

Table 3. Effect of using highly digestible Special Pre starter up to 4 days on Growth of broilers

The compensatory growth is well known and it can be successfully used to enhance the feed efficiency in broilers. Diluting the feed using high fibrous indigestible feed ingredients like rice hulls during the early stages of growth for a few days has been found to enhance the feed efficiency without affecting the final body weight. In an experiment (Table 4) when chicks were fed diets diluted with rice hulls recorded a better FCR even at 55% dilution, with a non-significant reduction in the final body weight. Whereas the group fed the diet containing 25% rice hulls recorded a better body weight and FCR.

Table 4. Effect on Diet dilution with Rice Hulls from , 4-11 days of Age, on Performance of Male Broiler Chickens

The need for reducing the carcass fat is well known as the consumers prefer lean meat. Further, reduction in the rate of fat deposition will improve the FCR as fat is used at a lower efficiency in body weight gain. Several trials have been conducted to achieve low carcass fat by dietary manipulations. Decreasing the ME of the diet from 15.1MJ/kg to 10.9MJ/kg reduced the carcass fat from 48% to 38% and increased the carcass protein from 43% to 51%. But under commercial conditions diluting the diet lead to lower body weights consequently increased the marketing age negating the benefits accrued. Similarly increasing the protein content of the diet reduced the fat content of the carcass. Increasing the protein content of the diet from 16% to 24% reduced the carcass fat to 42% from 50% and increased the protein content from 41% to 47%. The economical viability should be considered as protein is one of the costlier nutrients.

Feeding the broiler for higher efficiency is always more economical compared to other methods as it not only deals on the growth rate but on the overall functioning or the organization.

Brake,T. 2001. The First Load of Feed – Can We Do Better, In Proceedings of 2nd International Poultry Broiler Nutritionists Conference, Rotura, New Zealand.

Dautlick, J. and Stritmatter, C.F. 1970. Development of hormone-induced changes in chicken intestinal disaccharidases. Biochem. Biophys. Acta. (222) 444-454.

Dibner J., Dibner,J., Knight, C. D. and Ivey, F. J. 1998. The Feeding of Neonatal Poultry, World Poultry (14) 36-42.
Leeson,S. and Summers, J.D. 2005. Commercial Poultry Nutrition , Pp 250,258.

Author : Jayashree Desai,and Radhakrishna, P.M., Vetcare R&D Center, Bangalore-560064

Enzymes are the bio-catalysts produced endogenously in an animal’s body, for specific action on substrates present in foods/feeds, aimed towards release of energy for normal metabolism and maintenance of health.

Enzymes in animal feed industry are exogenous in origin, derived especially from microbes engineered for specific enzyme production in-vitro. They are special feed supplements which aim at improving “Digestibility” by acting in the gastro-intestinal tract of the animal.

The application of Enzymes are so versatile that they also find use in various industries like bakery, brewing, paper-making , etc., to name a few. In feed industry, some enzymes like Xylanases and ß-Glucanases are more than two decade old especially where wheat and barley were used as staple feed ingredients, for poultry and swine.

There are different classes of enzymes used in feed industry :
* Hydrolases
* Lyases
* Oxido-reductases

Of these the hydrolases are the ones enjoying a widespread use mainly in feeds for poultry and swine. The other two types of enzymes find minimum use in petfood industry along with hydrolases.

What are food enzymes?
These are geared towards improving taste, texture, appearance, nutritional value, shelf life and processing tolerance of food products.

What are feed enzymes?
These are aimed at improving the nutritional value and reducing the environmental burden .

	Increased need for quality food grains both for humans & animals
	Increased need for quality animal products/by-products
	Search for alternate sources of foods with better nutritive value
	Economic margins ( reduced cost: benefit ratio)
	Quick realization of profits
	The rise of environmental awareness

Either one or a combination of the above factors have contributed to the widespread awareness of the benefits of usage of exogenous enzymes . A methodical approach to investigative research has given us a vast & explored world of enzymes, which , has a bright future in this millennium.

Some of the widely used enzymes are as follows:

The “Environmental issue” that became a political debate was the rising awareness in Europe to reduce the phosphorus(P) output from animals . The target was to increase P utilization and decrease P output by atleast 30% in the Netherlands. The solution for which has been found in the use of “Phytase”, where it is possible to raise the digestibility of Phytate-P from 30% to 60% , reducing the requirement of mineral phosphates. An added advantage is that, in a feed with low total P, the amount of Calcium can also be reduced. Phytase in presence of endogenous acid phosphatase act synergistically to release bound P from phytates. Useful in feeds predominantly formulated with maize, wheat, wheat bran, rice bran, soya bean meal where the phytate content vary from 72% to 56%.

In our own experience from extensive field trials, the contribution to economy from layer poultry have come in the form of increased egg weights, egg production, feed intake and, decreased egg breakage and mis-shapen/leathery eggs.

Another series of useful enzymes are the “fibre-degrading enzymes” :
Under this category there are enzymes which act on degradation of non-starch polysaccharides (NSP) namely Cellulose, Pentosans (Xylans & Arabinoxylans), ß-glucans, Pectic polysaccharides, Mannans, Galactans ., etc.

Why are NSPs important?
NSP’s are cell-wall constituents whose action in poultry & pigs are termed “anti-nutritional” by virtue of their solubility & insolubility. The ‘soluble NSP’ exert viscosity increasing effects in-vivo under certain circumstances, whereas the ‘insoluble NSP’ are thought to encapsulate nutrients, thus acting as an antinutritional factor. However it is the former which play an important role in poultry.

In vitro evaluation Methodology:

The Efficacy of Non Starch Polysaccharide-hydrolyzing Enzymes can be evaluated In-Vitro by the following methodologies.

	Estimation of total, soluble and insoluble NSP fractions in feed/feed ingredients by Spectrophotometry and Gas Chromatography.
	By Gel Diffusion method which carries the specific substrate for the enzyme
	Sugar released under the specified conditions like pH, temp and time
	Qualitative Comparison of the viscosity ( Visco Test Kit) – In house Developed

Extensive research & studies conducted till date have proven that NSP-Hydrolyzing enzymes do reduce the viscosity in-vivo subsequently increasing the nutrient availability. They also enhance nutrient availability by releasing nutrients from the cells by way of breaking-down of the cell wall .

	In-house Farm trials (Statistically designed experiments)
	Ileal Digesta Digestibility
	Fecal matter Digestibility
	Production efficiency measures – Body weights and FCR
	Commercial field trials

Our studies on NSP-hydrolizing enzymes conducted at the research farm, has shown statistically significant increment in average body weights of 40-86 grams, FCR of 1.82±0.02 which was better by 6 points than control.

Another yardstick to measure the invivo efficacy is “ileal digesta” analysis for NSP. In cases where enzymes were supplemented, there was decrease in NSP to the extent of 45% as against 5% in control feed.

The fecal matter NSP analysis also can serve as a tool for efficacy determination, but may be misleading. The reason being that, the degradation of NSP occurs in the hindgut beyond ileum by microbial fermentation, which may be upto 20% even in non-enzyme-supplemeted feeds.

Based on the studies conducted in the Vetcare R&D Center, the following combinations of enzymes are recommended when certain feed ingredients are used in formulation of feeds.

	If the energy and protein sources are from Cron, Soya bean meal and fats, major enzymes required are Amylase, Cellulase, Pectinase, Protease and Phytase
	If sources differ to Rice, Groundnut extract, Wheat or Sunflower extract, the major enzymes required are Amylaxe, Xylanase, Pectinase and Phytase
	If diets contain fibre-rich components like De-oiled rice bran / Sunflower extract / GNE / Mustard extract alongwith corn and soya, major enzymes required are Glucanase, Xylanase and Pectinase

One very important task faced by an Animal Nutritionist is Product development. A developer has to understand that the enzyme and substrate act as lock and key.The enzyme can only do its work on a specific substrate until it is available., and no more. Eg: Phytase acts on phytates. An excess of enzymes is always wasted in the absence of adequate quantity of specific substrate.

Sometimes there is failure of performance of enzymes… which is a complaint often heralded. Some of the reasons attributed are

	Incompatibility of enzymes with the feed ingredients.
	Enzymes are sensitive to pH, temp
	Digestibility and immunity of the animal
	Lack of knowledge of application of enzymes in feed
	Inadequate quantification of feed consumption in commercial farming

Conclusion :
Enzymes are an integral part of animal feed industry as on today. The future is also dependant upon delivery of nutrition by scientific yet economic means. Science is essential but economy always leads. Enzymes in feed do have a promising future in this millennium. But, the success depends on the ability of the feed manufacturer to integrate the knowledge of substrates, enzymes and associated technology.

Nonstarch polysaccharides ( NSPs ) in monogastric feed has measurable ANFs ( Anti Nutritive Factors ) which results in wet droppings and poor use of nutrients. Usage of Microbial enzymes targeting these polymers have shown positive results , both in performance enhancement coupled with reduction in volume and moisture content of droppings. Decreased output of organic matter (OM) to the environment is an important attribute of feed enzymes because , excessive output of nitrogen and phosphorus poses a major problem in densely populated areas.

Enzymes also allow us to use a wide range of alternative ingredients without compromising the performance of poultry & facilitates great flexibility to compute “ Least- Cost Feed Formulation “.

Other possible benefits of enzymes are , they alleviate gastrointestinal morbidity and other diseases in animals like, swine dysentery and acidosis in ruminants and horses.

Benefits through increased nutrient digestibility and decreased excreta output

Dry-Matter Digestibility (DMD) in animals ranges from 50 to 70% and the balance is excreted through the droppings. In densely populated areas , excretion of large amounts of Organic Matter, especially with high levels of nitrogen and phosphorus pose serious environment pollution problems.

Currently, cocktail enzyme formulations are being widely used in monogastric feed to increase nutrient digestibility and to decrease nutrient waste through droppings.

The effect of enzyme supplementation in Swine and Poultry depends on the type of feed and category of animals. Cocktail enzymes application increases Dry Matter Digestibility as reported by Schutte et al. 1995 ,from 0.9 to 17% in poultry and from 0 to 5.2% in Swine by Schmitz 1995.

The cocktail enzymes currently used in monogastric feed ,cleave NSPs into smaller polymers, there by removes their ability to form viscous digesta and enhances nutrient digestibility.

The solitary enzyme PHYTASE , used in feed increases the utilization of phytate phosphorus. Phytase improves the digestion of phytate phosphorus and subsequently reduces output of organic phosphorus into the environment. This attribute of phytase has attracted both scientific and commercial arenas of poultry and swine industry.

Supplementing pig diets with 500 U phytase activity/kg feed increased the digestibility of phosphorus from 44.2% to 52.4% (18.6% increase) and that of calcium from 44.2% to 51.7% (17.0% increase). Supplementing piglet diets with 1500 U phytase activity/kg feed also significantly improved the weight gain (from 424 g/d to 529 g/d) and FCR (from 1.65 to 1.52) (Jongbloed et al. 1993).

In poultry, phytase use was reported to reduce phosphorus excretion by as much as 40% for broilers (Simons and Versteegh 1991). When phytase was added to layer diets, increased egg production and positive effects on egg weight and tibia ash were also noted (Simons and Versteegh 1993).

Cereal by-products, such as rice bran, are important feed ingredients in Asia, but their efficient use in monogastric diets is hindered by the presence of high levels of NSPs and phytates. Martin (1995) demonstrated that supplementing duck diets with microbial phytase allowed rice bran to be used at high levels (up to 60%) without detrimental effects. Phosphorus excretion was reduced by 9.6%, and significant decrease in excretion of manganese, copper, and zinc were also noted.

Wet droppings is one of the major problems in poultry industry, especially in the case of laying hens, where increased percentages of dirty eggs are associated with wet droppings. In many countries, dirty eggs are graded as “ Not suitable for sale “ resulting in economic loss for the industry.

Wet droppings may increase the production of gases like ammonia and hydrogen sulfide. Wet droppings also increases fly and rodent populations in swine and poultry sheds. These can affect the health of the animals by increasing stress and lowering air quality. They also affect the health of the personnel who work in the shed (Donham 1995).

Reduction in the moisture content of poultry droppings is often noted , when cocktail enzymes are included in the feed. In a trial, when an equivalent of 4% soluble NSPs was added to a sorghum-based broiler diet, bird’s performance was significantly depressed and the moisture percentage in droppings increased from 47.4% (in birds fed the basal diet) to 64.5%. Supplementing the NSP-enriched diet with three different commercial formulations, improved performance, but their effectiveness in reducing the moisture levels of the droppings differed from 10 to 29%.

This supports the view that different formulations have similar performance-enhancement effects in monogastric animals , but the site of the breakdown of the NSPs in the gut and the molecular sizes of the released products differ. These important differences determine the efficacy of a cocktail formulation in reducing the moisture content of the droppings.

The use of enzymes to alleviate the problem of wet droppings is not only limited to just pigs and poultry, but also in household pets which can create environmental pollution problems.

Some disease conditions, such as swine dysentery and acidosis in ruminants and horses, have great economic significance and are closely related to the status of the gut microflora (fermentation). For example, swine dysentery is caused by a spirochaete bacterium that resides in the large intestine, and the proliferation of this bacterium is inhibited by low rates of fermentation, as indicated by Siba et al. (1993, 1995). The increased fermentation in the large intestine may be due to an elevated level of NSPs in the feed. Glycanases may offer an alternative solution to the problem. For instance, the production of short-chain fatty acids in the cecum, colon, and rectum was significantly reduced by adding ß-glucanase to a barley-based pig diet (Inborr et al. 1995).

In ruminants, absorption of glucose from the intestine can markedly improve fat synthesis and glycogen stores. The fermentation of starch in the gut can lead to significant clinical and subclinical problems in both ruminants and horses. Secondary problems include laminitis (lameness) and poor utilization of minerals. These problems significantly affect health, productivity, and waste management (Murray et al. 1991; Godfrey et al. 1992). The nature and quantity of the starch and fibre components influence the extent of digestion or fermentation, as well as the location within the gut where the digestion or fermentation occurs. Although the use of enzymes for ruminants and horses is not widespread, the manipulation of carbohydrate digestion in these species may be a great "hidden benefit" for enzyme users in the future.

The significance of gut microflora to the nutrition of chickens is not well documented. Excessive fermentation in the small intestine may interfere with the normal physiological process of nutrient digestion. As often noted, adding antibiotics to poultry feed containing highly soluble NSPs markedly improved bird’s performance (Misir and Marquardt 1978). Elevated levels of intact soluble NSPs detrimentally increased the activity of fermentative microorganisms in the small intestine (Choct et al. 1996). Xylanase supplementation largely eliminated fermentation in the small intestine and improved the performance of the birds.

A sudden change in the gut ecology (from an aerobic or facultative anaerobic environment to a strictly anaerobic one) may induce gastrointestinal stress and severely affect the normal physiological processes. Morgan and Bedford (1995) reported , coccidiosis problems could be prevented by using cocktail enzymes.
Cocktail enzymes when used in poultry feed, reduced viscocity , increased passage of digesta and decreased moisture content of droppings which are detrimental to the life cycle of Eimeria species .

Benefits through increased precision & flexibility in Least-Cost Feed Formulation

The nutritive value of cereal grains for poultry varies greatly, and no suitable assays are currently available for rapid testing. Enzymes allow a wide range of ingredients to be used in feed for a desired outcome. This gives the producer a great deal of flexibility in formulating a nutritionally balanced, least-cost diet.

Various benefits of cocktail enzymes application in feed can be listed as follows :

To achieve the fast growth potential, young poultry must endure a shift in energy metabolism and nutrient supply dynamics post hatch. Birds have a gastrointestinal tract that enhances the rate of digestion enabling a fast throughput of feed. Early intake of carbohydrates is needed for maturation of energy metabolism and a balance of other nutrients (i.e. amino acids) is required to optimize subsequent performance (Moran, 1990).

After hatching, the bird requires oral nutrient intake to stimulate further development of the gastrointestinal system (i.e. intestinal weight, villus length, endogenous enzymes), but there is debate as to which of these factors may limit early growth. Hence supplementation with specific amylases, preferably in the presence of cell-wall opening carbohydrases, may improve nutrient digestion in the upper intestinal tract resulting in improved energy retention and animal performance. Supplemental enzymes thus are complementary to this end and their use in practice is particularly attractive when these supplements can withstand feed pelleting. The following is an overview of events in digestion, which may explain when and where advantages from feed enzyme supplements occur in low-viscous based diets.

It has only recently emerged that corn and soybean meal can pose digestive problems to poultry. However, recent advances in technology have exploded the myth that these diets cannot be enhanced with enzymes. New, specifically designed enzyme products have been developed that offer broilers fed on low-viscous cereal diets improved performance.

Corn has traditionally been the preferred cereal for domestic animals, with its dietary energy value being the highest of the cereals The energy content of corn and sorghum are considered relatively constant partly based on the anticipation of highly digestible carbohydrates, but the digestion of these nutrients may be directly impacted by many factors. For example, harvesting conditions can have a substantial influence, as reported by Leeson et al (1993), when weather conditions resulted in delayed and wet corn harvest in the 1992 Ontario crop, and AMEs varied from 1330 to 1579 kcal/lb.

Corn starch is anticipated to have a high excreta digestibility in birds (>98%), but recent data reported by Noy and Sklan (1995) revealed a surprisingly low ileal digestibility of both starch and fat in young broiler chicks fed a corn-soybean meal diet supplemented with 6% soybean oil. When determined in birds at various ages between 4 and 21 days, starch digestibility up to the end of the small intestine was as low as 82%, with no evidence of any increase as the birds got older. This suggests that a significant portion of the corn starch might reach the hindgut and undergo fermentative breakdown.

This theory is supported by recent microscopic examinations of ileal digesta obtained from the ileum of corn-soybean meal fed broilers. Microscopic images of ileum digesta gave clear evidence for large corn endosperm particles remaining undigested in the chick (Autio & Poutanen, VTT Biotechnology and Food Research, Espoo, Finland). Overall, it appears that corn starch (and fat/protein) digestion may not be as complete in the chick as previously thought.

Soybean seeds consist mainly of protein, oil, carbohydrate and minerals. In cultivated varieties, roughly 60% of the seed mass is oil plus protein, although genetic and environmental factors can cause substantial variation in the levels of these two constituents. The composition of the various fractions are affected significantly by the variety and the growing conditions of the soybean itself, as well as subsequent processing methods. A recent survey carried out by Finnfeeds International examined the variation in soybean meal quality collected from different locations in the world (Hessing et al., 1995, see Pack et al., 1996). This clearly showed soybean meal to be a fairly variable ingredient, contrary to what is generally accepted.

Previous work on enzyme treatment of soybeans during processing had shown the opportunities of using proteases to degrade both trypsin inhibitors and lectins (Huo et al, 1993). Subsequent trials confirmed these effects and indeed demonstrated improvements in protein digestibility and broiler performance due to protease pre-treatment of soybeans (Table 1). This highlights the potential for effective removal of antinutritional factors during feedstuff processing. Alternatively, proteases added to the feed could be considered for the same purpose.

Table 1. Effect of protease treatment during soybean processing on protein digestibility and performance in broilers (Ghazi et al, 1996a,b)

Recently, Finnfeeds International has initiated the use of enzymes specifically designed to tackle corn- or sorghum-vegetable protein broiler diets. Being a complex of -amylase, xylanase and protease, this specific enzyme mix targets mainly the cereal starch and the vegetable proteins. The B. subtilisin -amylase is aimed at working in the upper region of the gastrointestinal tract of the animal to correct for incomplete endosperm starch digestion.

The Trichoderma longibrachiatum xylanase in this cocktail has been successfully used in enzyme products targeting wheat, and has proven effective to reduce viscosity, degrade cell walls and release xylo-oligomers. One of the main features of this xylanase is its broad pH profile (3.5-6.5) which enables the enzyme to act throughout an extensive portion of the gastrointestinal tract, from the initiation of digestion to the ileum. In addition, there is some evidence that xylo-oligomers, resulting from the breakdown of xylans by the xylanase, are effective in stabilizing the gut microflora of the chick, thus possibly stabilizing the health status of the bird.

The Subtilisin protease included in this enzyme product is characterized by a high catalytic efficiency. This protease degrades soy proteins, namely the soy storage proteins, conglycin and beta-conglycinin, and the soy antinutritional factors such as trypsin inhibitors, lectins and antigenic proteins. The efficacy of this protease has been established both in vitro through Western Blot analysis, screening the activity of different proteases at different concentrations on the soy proteins, and in vivo by testing animal performance at different dosage rates.

With the new lean genetic lines, even more pressure in broiler production is placed on the gastrointestinal system that progresses from a sterile immature one at hatch to one fully competent with a mature large intestinal microbial population at marketing. Birds receiving corn as the dominant feedstuff do not encounter viscosity problems of the luminal contents that limit nutrient absorption such as created by the soluble fiber in wheat, barley, and rye. Corn together with other feedstuffs (i.e. soybean meal) presents other limitations in digestion where a different array of supplemental enzymes could be of benefit.

Extensive research has shown that supplementation with high levels of a specific amylase and protease, in the presence of cell-wall opening xylanase, may improve nutrient digestion in the upper intestinal tract of a corn-based diet resulting in improved energy utilization and bird performance. The approach in these studies is to determine ileal digestibility in young broiler chicks as opposed to the commonly used adult rooster assay, because the latter has been shown to be much less sensitive to pick up batch-to-batch differences between cereals, or to detect enzyme effects on energy digestibility. Trials at the University of Minnesota (Coon, unpublished 1997) have found a significant increase in ileal digestibility values for starch and energy at 35 days of age supporting improvement in performance (Table 2). However, in this trial the 6.4% improvement in energy at the ileal level was not observed at the fecal level. This difference may be partially explained by the ability of the microflora in the control group to utilize these nutrients for their own energy at no large benefit to the growth of the bird. Over five trials the increase in ileal energy has ranged between 3 and 12% with an overall average of ~6.0%. It appears that there was a very substantial effect on energy digestibility in these studies, whereas the enhancement in protein digestibility may depend on the actual quality of the protein feedstuffs used.

Recent trials were conducted at Auburn University to investigate the impact of these enzymes when fed with different dietary nutrient levels. The objective of first experiment was to measure the response of male broilers to enzyme supplementation when crude protein was reduced in a corn-soya pelleted diet while essential amino acids are maintained at requirement levels. All diets had the same energy levels (1455 kcal/lb: NRC) in the starter, grower and finisher diets, but treatments 1& 2 had ~15% higher protein compared to diets 3& 4 (Table 3). At day 49, birds fed the high protein diets significantly outperformed (~2.5%) the low protein groups and had less abdominal fat (Table 4). Enzyme addition to both diets significantly improved overall feed:gain (by ~2.5%) and reduced abdominal fat (~4%) with no effect on body weight. There was an interaction with the response to enzymes being larger in the group fed the high protein diet compared to the low protein based diet.

Table 2. Effect of enzyme supplementation on nutrient digestibility values and performance in broilers fed a corn-soya based diet. (Coon, unpublished 1997)

Control + Enzyme¹
Day 35- digestibility values
Ileal starch , % 75.2    85.8
Ileal energy, kcal/kg (kcal/lb) 2718 (1235)   2893(1315)
Fecal energy, kcal/kg (kcal/lb) 2807 (1276)   2814(1279)

Table 3. Composition of broiler feeds that satisfy NRC (1994) nutrient recommendations and those decreasing crude protein while continuing minimum levels of essential amino acids, % 'as is'. 0-21 d 21- 42 d 42- 49 d

High Low High Low High Low
Corn 59.6 61.6 68.9 70.8 75.7 79.3
SBM-48 21.6 26.3 15.1 20.2 9.4 13.1
Corn gluten 7.6 - - - 7.7 - - - 8.9 0.4
Fishmeal 5.1 3.1 4.0 2.3 3.0 3.0
Poultry fat 3.0 4.7 1.3 3.0 - - - 1.0
Limestone 1.0 1.1 1.0 1.0 1.0 0.9
Dical. Phos. .95 1.3 0.9 1.3 0.8 0.9
Lysine .25 .25 0.3 0.3 0.4 0.4
D,L - methionine .10 .30 0.5 0.2 - - - 0.1
L- threonine - - - .05 - - - 0.1 - - - 0.1
Potassium Cl - - - - - - - - - - - - 0.10 - - -
AME (kcal/lb) 1459 1455 1450 1459 1459 1455
Protein (%) 24.1 21.0 20.7 17.5 18.3 15.4

All feeds received the following (%): salt, .35; micro vit.-min mix, 1.0; coccidiostat, .08. Supplemental enzymes when included (0.1%) substituted for corn on a w/w basis.

Table 4. Effect of enzyme supplementation¹ on performance and carcass quality of broilers fed a corn-soya diet with different protein levels to 49 days of age².

Body Feed: Adj.³ Abd. Carcass
Protein Enzyme weight gain Feed:gain fat yield
(g) (%) (%)

High prot. 0.0 3024 1.91 1.903 2.25 66.3
0.1 3053 1.86 1.844 2.16 66.3
Low prot. 0.0 2956 1.96 1.973 2.60 66.4
0.1 2996 1.92 1.921 2.50 65.3
Protein * * - - - *** NS
Enzyme NS * - - - * NS
Prot x enz NS NS - - - NS *
SEM 17.8 0.015 - - - .036 0.32

¹ Enzymes displaced 0.1% corn
² Late summer conditions: average temperature 23-28ºC, 75 85% relative humidity.
³ Corrected 3 points per 100 g live weight to 3000g

Added fat is a costly source of dietary energy; and if supplemental enzymes could compensate reduction in use then favorable economics exist. Thus, a second experiment was conducted to investigate the response to supplemental enzymes when added fat was replaced with corn as a straight substitution. Directly replacing added fat with corn decreased the dietary energy levels 3.9% in the starter, and ~9% in the grower and finisher diets (Table 5).

Adding an enzyme product to corn-soya feeds already satisfactorily balanced or with excess energy does not readily lead to a perceptible improvement. On the contrary, additional energy derived from the supplemental enzymes may create an adverse balance with existing protein and amino acids minimizing the economic payback (Table 6). Reducing dietary energy such as a decrease in added fat may be necessary in order to realize a productive advantage from this type of enzyme product . This trial indicates an enzyme product can release dietary energy from a corn-soya diet resulting in performance equivalent to a high energy control diet.

Table 5. Composition of broiler feeds occurring with the substitution of added fat with corn, % 'as is'.
0-21 d 21- 42 d 42- 49 d

NRC w/o fat NRC w/o fat NRC w/o fat
Corn 59.2 61.6 60.9 66.2 65.2 70.7
Poultry fat 2.40 - - - 5.30 - - - 5.45 - - -
SBM-48 25.35 23.50 21.00
Fishmeal 4.00 3.00 2.00
Poultry meal 4.00 3.00 2.00
Corn Gluten-60 2.00 1.00 1.00
Limestone 0.80 1.00 1.00
Dical. Phos. 0.75 0.90 0.85
D,L-methionine 0.06 0.04 0.09
AME (kcal/lb) 1432 1377 1509 1386 1532 1405

All feeds received the following (%): salt, .35; micro vit.-min mix, 1.0; coccidiostat, .08. Supplemental enzymes , when included (0.1%) substituted for corn on a w/w basis.

Table 6. Effect of enzyme supplementation1 on Day 49 performance and carcass quality of broilers fed a corn-soya diet with corn directly replacing fat.²

Body Feed: Adj.³ Abd. Carcass
Added fat Enzyme weight gain Feed:gain fat yield
(g) (%) (%)

¹ Enzymes displaced 0.1% corn
²Summer conditions: average temperature 27-29ºC, 79 85% relative humidity.
³ Corrected 3 points per 100 g live weight to 2850g.

There are two main approaches when considering incorporation of enzymes into corn-soybean feed formulations for broilers. The simplest, and the one that might be of more practical application for the young bird, is the 'over the top' addition to an existing formulation to cost-effectively improve broiler performance. An example of a recent US trial testing such an approach is shown in Table 7, where addition of feed enzymes were tested in two different diet densities. Both diets were corn-soybean meal based and contained about 5% meat & bone meal. Exceptional performance was achieved both at standard diet density (1420/1445/1475 kcal/lb for starter/ grower/finisher) as well as with diets formulated to reduced ME, protein and amino acid specifications. Both diets clearly responded to addition of feed enzymes . However, as mentioned earlier the response is predominantly coming from increased ME levels, thus the diets must contain adequate levels of amino acids to support this additional energy.

Table 7. Effect of 'over the top' addition of feed enzymes on performance of broilers fed corn-soybean diets of different density to day 49.

¹ P value for overall enzyme effect
²Corrected 3 points per 100 g live weight to 3100 g live weight

The alternative option is to change the feed formulation to reduce the cost per ton of feed and, through the addition of feed enzymes, restore the nutritional value of the feed, resulting in performance similar to the normal feed formulation. Various approaches to this concept are currently evaluated under a wide variety of dietary specifications and husbandry conditions. For the time being, it is suggested to include the enzyme and reduce the dietary energy specifications by up to 5% to take advantage of cost savings in diet formulation while maintaining bird performance. This is the method recommended in the US which tend to use high dietary energy levels in low amino acid diets to achieve optimal benefit from the enzymes.

An example of a recent trial testing such an approach is shown in Table 8, where the dietary energy levels were decreased 3, 5 and 5% in the starter, grower and finisher diets, respectively while maintaining the same amino acid levels. Good performance was achieved both at standard diet density (1418/1445/1473 kcal/lb for starter/ grower/finisher) as well as to the low energy diet with the addition of feed enzymes The enzymes compensated for lost broiler performance in reduced energy diets and significantly reduced body weight variation.

Table 8. Effect of the addition of feed enzymes on performance of broilers fed corn-soybean diets of different densities to day 49

¹ Commercial FCR, not adjusted for mortality
² Corrected 3 points per 100 g live weight to 3000 g live weight
³ Body weight uniformity is based on one standard deviation.

An important finding in this data review was the repeated observation of reduced variability of bird body weight at the end of the growing cycle. This suggests more uniform nutrient availability to each bird and more consistent flock growth throughout the production cycle.

Conclusions

The use of feed enzymes in broiler diets based on viscous cereals such as wheat or barley is well established in all markets where these grains are available at attractive prices. In diets based on the low-viscous cereals (corn and sorghum) along with soybean meal, the use of enzymes specifically designed for these substrates is now under investigation. Results of growth and digestibility studies show an important potential for improvement in energy and nutrient digestibility. Further important aspects include a reduction in bird body weight possibly from more uniform nutrient availability. The current results demonstrate that a proper enzyme product can have a direct effect on ileal energy availability from a corn-soya based broiler diet, although this improvement in available energy may interact directly with the nutrient density of the diet. One must account for this energy uplift to maintain a properly balanced diet to obtain optimal economic performance. Other advantages such as protein and phosphorus digestibility are also likely, but realization depends on feedstuffs and degree of limitations.

Craig L. Wyatt., Ph.D. and Michael Pack, Ph.D.
Finnfeeds International, Inc.
St.Louis, MO 63026, USA

Attributes	LF	HF	HF1
Mean Live Weight(g)	1552	1377	1483
Body Weight gain (g)	1504a	1322b	1438a
Feed intake (g)	3623	3736	3568
Feed efficiency	2.41b	2.80a	2.48b
Feed efficiency ratio	0.415a	0.356b	0.403a
Performance index	624a	475b	579b
Cost/quintal diet (Rs.)	570	517	547
Feed cost / kg live weight (Rs.)	13.68	14.73	13.56

Enzyme(s)	Level(s)
Cellulase	420 IU / kg
Xylanase + Pectinase	4025 IU and 5 IU/kg, respectively
Xylanase + Pectinase	40253 IU and 53 IU/kg, respectively
Xylanase + pectinase + a-galactosidase	40253 IU, 53 IU and 20 IU/kg, respectively
Xylanase + pectinase + a-galactosidase + cellulase	40253 IU, 53 IU, 20 IU and 560 IU/kg, respectively

NSP Component	Maize	Soyabean Meal
Arabinose	1.9	2.0
Xylose	2.4	1.8
Mannose	0.2	0.6
Galactose	0.4	2.9
Glucose	2.6	6.7
Uronic acid	0.6	2.5
Total NSP	8.1	17.2

NSP Component	Starter diet	Finisher diet
Arabinose	1.68	1.69
Xylose	1.91	1.93
Mannose	0.29	0.28
Galactose	1.10	1.03
Glucose	3.49	3.40
Uronic acid	1.09	1.05
Total NSP	9.79	9.58

Enzyme(s)	Level	Type of birds	Type of feed	Effect on performance
1. Anizyme, allzyme BG, ventrigold	-	Broiler	Low/normal energy	Superior weight gain and FCR than control.
2. Multi-enzymes preparation	500 g/tone	Broiler	Raw/ autoclaved millets	Better FCR and P balance.
3. Multi-enzymes preparation (ß-D-Glycosidase, cellulase, protease, anaylase and phytase)	500 g/tone	Broiler	Commercial poultry feed	Significant improve-ment in body weight.
4. Fibrolytic enzyme - Nutrizyme (xylanase, pectinase and cellusase)	0.1%	Layers	Energy levels - 2000 to 2700 kcal/ME/kg	Significant improve-ment in egg product feed efficiency and decreased viscosity except in high-energy group (2700 kcal/ME/kg.
5. Multi-enzyme preparation	-	Broiler	Broiler diet having dried poultry excreta (0-10%)	Improvement in the performance.
6. Multi-enzyme preparation	-	Broiler	Apple pomace replacing maize (15-20%)	Improvement in feed conversion efficiency.

Feedstuff	Cellulose	ß-glucane	Arabinoxylane	Pectin
Corn	2.6	-	4.9	0.7
Wheat	2.5	0.8	6	20.3
Barley	4.3	4.4	3.3	0.6
Soybean	4.6	-	-	4.8

Soybean Meal	Trypsin inhibitors, lectins, saponins, raffinose, stachyose
Rapeseed meal	Glucosinolinates, tannins, phenolic acids, fiber
Sunflower meal	Fiber, tannins
Lupins	Alkaloids, fiber
Peas	Lectins, tannins, fiber, oligosaccharides

Enzyme Level (BGU/kg of feed)	Feed Intake (g/bird)	Body Weight (g)	FCR
0	^96.5a	^2163a	^1.742a
100	^95.0ab	^2193ab	^1.692b
200	^95.3ab	^2215b	^1.678b
400	^93.2b	^2160a	^1.685a

Parameter	Control	Pentosanase (1000 XU/kg)	SED	P Value
Daily gain (g)	34.0	36.6	0.475	0.001
Daily Intake (g)	54.0	54.8	0.641	0.05
Feed efficiency*	0.634	0.657	0.003	0.001

Parameter	Control	Enzyme Supplemented (500g/t)
Weight Gain 15 days (g)	549	569
Weight Gain 29 days (g)	1463	1500
FCR 15 days (kg/kg)	1.617^a	1.559^b
FCR 29 days (kg/kg)	1.733^a	1.707^b

Amino Acid	Control	Enzyme supplemented(1-kg/t)
Alanine	72.4	72.8
Aspartamine	67.0	69.6
Cystine	41.6	57.9
Glutamine	82.7	84.6
Histidine	54.7	68.5
Isoleucine	81.0	82.8
Leucine	80.6	82.0
Lysine	82.1	86.0
Methionine	65.4	69.0
Phenylalanine	86.3	88.9
Proline	70.0	77.4
Serine	78.6	83.9
Threonine	72.7	78.5
Tyrosine	74.3	77.1

Age	Mean Weight	Cal Conv (Kcal/kg)
wks	(g)	(Kcal/kg)
1	141	2936
2	359	3864
3	675	4544
4	1132	5110
5	1643	5504
6	2155	5951

Protein turnover	7th d	14 th d	28th d	42th d
Protein synthesis	702	1193	2521	5086
Protein degradation	226	569	1338	3914
Protein gain	476	624	1183	1172

Feed type	Age in days
	4	7	21	33	42
Special Pre-starter (0-4d)	117	190	820	1900	2670
Conventional	87	150	700	1700	2450
Difference %	34	21	17	12	9

Diet Dilution	Body weight (g)					Feed:Gain		Adjusted Feed:Gain 0-42 d
Diet Dilution	4d	11d	21d	35d	42d	4-11d	0.42d	Adjusted Feed:Gain 0-42 d
0	101	276a	720a	1673a	2149	1.33d	1.73	1.73
25	100	260b	696a	1668a	2159	1.71c	1.71	1.68
40	98	240c	659b	1612a	2093	2.18b	1.74	1.68
55	98	219d	604c	1532b	2029	2.75a	1.72	1.63

	Untreated control	Protease treated
Ileal digestibility (%)	79.5^a	84.9^b
Excreta digestibility (%)	78.2^a	83.3^b
N retention (%)	58.1^a	67.1^b
Weight gain, 7-27 d (g/d)	36^a	41^b
Feed : Gain	1.98^a	1.92^a

	Standard density		- 4% ME & CP/AA
1-49 days	Control	+ Enzymes	Control	+ Enzymes	P¹
Weight gain (g)	3140^b	3270^a	3063^b	3124^b	0.02
Feed Intake (g)	5344	5467	5379	5430	0.07
FCR (Feed : Gain)	1.70	1.67	1.76	1.74	0.30
Corrected FCR²	1.69^ab	1.62^a	1.77^b	1.73^b	0.09

	Standard density	Reduced energy diets -3, 5 & 5% ME
1 - 49 days	Control	Control	+ Enzymes
Body weight, g (lb)	2958 (6.51)	2958 (6.51)	2981 (6.56)
Body wt. uniformity³, g	69^a	40^a	12^b
FCR (Feed : Gain)¹	1.92^a	1.99^b	1.92^a
Corrected FCR ²	1.93^a	2.00^b	1.93^a