Feed enzyme preparation is a new type of green feed additive that is efficient, non-toxic and residue-free. It can effectively regulate the nutritional physiology of the animal’s digestive tract, the microecological balance and the physical and chemical properties of chyme, and improve the production of animals. performance, increase economic and ecological benefits, so it is favored by the feed industry and breeding industry.
Enzyme preparations are a type of protein extraction and processing products with catalytic activity. They are produced by fermentation of active microbial cells. Probiotic microorganisms such as bacteria and fungi are the main sources of enzyme preparations [1]. At present, enzyme preparations are used in animal feed production as a safe feed additive. They can improve the feed processing technology and make the feed more suitable for the digestion and metabolism of the animal body. By improving the digestibility and utilization rate of the feed, the animal production performance can be improved. Reduce nitrogen and phosphorus excretion, thereby reducing environmental pollution.
1 Classification of feed enzyme preparations
1.1 Single enzyme preparations
Single enzyme preparations can be divided into digestive enzymes and non-digestive enzymes. Digestive enzymes mainly include starch Enzymes, glucoamylase, protease, lipase, etc. mostly work in the gastrointestinal tract of animals and have relatively single ingredients.
Amylase can hydrolyze starch into disaccharides, oligosaccharides and dextrins, making them easier to absorb and promote digestion; glucoamylase can hydrolyze linear oligosaccharides, disaccharides and dextrins into glucose and fructose, It can also work with amylase to completely decompose starch into glucose; protease is divided into acidic, neutral and alkaline according to its properties. Animal gastric juice is mostly acidic, and the intestinal tract is mostly weakly acidic to neutral, so the protease added to the feed Most enzyme-like preparations are acidic or neutral and can hydrolyze feed proteins ingested by animals into peptides or amino acids; lipase can decompose fat into glycerol, fatty acids and phosphatidic acid.
Non-digestive enzymes include cellulase, hemicellulase, pectinase and glucanase. Cellulase includes C1 enzyme, Cx enzyme and beta-glucosidase (Cb). Under the action of cellulase, cellulose can be completely decomposed into glucose that can be used by the body. Hemicellulase is mainly composed of xylanase, mannanase, arabinase and polygalactosidase. It can degrade hemicellulose in plant cells into five-carbon sugars, cellulase and hemicellulase. Synergy can destroy cell walls and break down polysaccharides that are difficult to digest, thereby improving feed utilization. The main function of pectinase is to decompose pectin located in plant cell walls and intercellular layers. Beta-glucanase can catalyze the hydrolysis of beta-glucan in grain cell walls to generate glucose and disaccharides, so that nutrients can be released and utilized.
1.2 Compound enzyme preparation
Compound enzyme preparation is composed of two or more single enzyme preparations. According to different functional characteristics, it can be divided into - glucanase as the main one Feed compound enzyme preparations, feed compound enzyme preparations based on protease and amylase, feed compound enzyme preparations based on cellulase, xylanase and pectinase, phytase preparations, etc.
The effect of compound enzyme preparations is better than that of single enzyme preparations. Its main function is to supplement the deficiency of animal digestive enzymes, degrade biological macromolecules such as polysaccharides and proteins in livestock and poultry, and also destroy plant cell walls. , release nutrients in cells, reduce anti-nutritional factors, increase the nutritional value of feed, and promote animal digestion and absorption; the appropriate addition of some enzyme preparations (such as phytase) can partially or completely replace the inorganic components added to the feed to meet the needs Ecological and environmental protection requirements.
2 Application of feed enzyme preparations in poultry production
The use of feed enzyme preparations in poultry production can improve the utilization rate of poultry diets and reduce the effect of anti-nutritional factors , improve feed remuneration, and can also enhance the immunity of poultry to a certain extent and reduce the pollution of poultry to the environment.
2.1 Chicken
The unique digestive tract structure of poultry determines that it is difficult for them to digest the plant feed they ingest. Moreover, the intestinal tract of poultry is short and it is difficult to provide enough enzymes to Decompose the crude fiber content of feed.
2.1.1 Broiler chickens
The special digestive characteristics of the chick stage cause the daily weight gain of the chicks to increase and the feed-to-weight ratio to decrease after adding enzyme preparations. Experimental results by Zhang Hongfu and others show that adding 0.05% to 1% of complex enzyme preparations to broiler chicken diets can increase daily weight gain by 4.6% to 9.4% and increase feed return by 3% to 5.5% [2].
Gu Weizhi's experiment showed that when 21-day-old Avian broilers were fed corn-mixed meal diets with compound enzyme preparations, the daily weight gain of the enzyme preparation group in the diet increased by 8.07% compared with the mixed meal diet group, and the feed-to-weight ratio was reduced. 12.02%, the differences are significant (p0.05) [3]. Zhang Qin et al. reached similar conclusions in the experiment [4]. Tang Haiou et al. studied the effects of adding different doses of complex enzyme preparations to different types of diets on the growth performance of broilers. The test results showed that the average daily weight gain of the chickens in the 400 and 800gt-1 groups of complex enzyme preparations was significantly higher than In other groups (p0.05), the feed-to-meat ratio decreased by 4.76% to 6.88% compared with the negative control group, and the difference was extremely significant (p0.01) [5]. Qian Lichun et al. added complex enzyme preparations to the basic diet of commercial AA broilers. The results showed that the jejunal digesta viscosity of broiler chickens decreased by 16.62%, and the number of Escherichia coli in feces decreased by 61.22% (p0.01). There was no significant effect on the villus height of the intestinal mucosa, but the villus width increased by 48.0% (p0.01) [6]. It is consistent with Zhang Shengyin’s report [7]. Geng Dan et al. added a crude enzyme preparation derived from microorganisms to the diet of broilers. The results showed that after adding the enzyme preparation, the average weight gain of the test group was 3% higher than that of the control group. The weight of the chickens in the test group was generally higher than that of the control group; The weight of the entire digestive tract decreased compared with the control group. The total weight of the gizzard and glandular stomach was reduced by 5.3% compared with the control group. The total intestinal weight was reduced by 19.2% compared with the control group (p0.05). The total intestinal length was reduced by 5.3% compared with the control group (p0.05). decreased by 12.7% (p0.05), and the evisceration rate increased by 14.5% (p0.05) compared with the control group; the crude enzyme preparation reduced the pancreatic protease activity of broiler chickens by 194.7% (p0.01), and the pancreatic amylase activity showed little change. ; The activity of small intestinal protease increased by 41.3% (p0.05), and the activity of small intestinal amylase increased by 36.7% (p0.05) [8].
The feed structure has changed during the breeding period. Research by He Wanling and others found that cellulase preparations can significantly increase the weight gain of broilers (p0.05) and significantly reduce the feed weight gain ratio (p0.05). Moreover, the group adding 0.10% cellulase preparation had good production performance, which is consistent with the conclusion drawn by Zhou Juan et al., but slightly different from Feng Jianmei’s conclusion, which may be caused by the different age stages of the chickens [9-11 ].
The effects of enzyme preparations on the apparent digestibility and metabolizable energy of chickens are not completely consistent, but are related to the type of feed and are relatively specific. Zhao Biqian et al.'s research results show that adding NSp enzyme preparations to the corn-soybean meal type diet of broiler chickens from 1 to 21 days has no effect on the production performance and apparent nutrient utilization of broiler chickens, while adding high miscellaneous meal (rapesee meal 3%, Adding NSp complex enzyme preparation to the corn-soybean meal-mixed meal broiler diet (cotton meal 3% and DDGS 8%) can improve the production performance of broiler chickens on 22-42 days and 1-42 days, and can improve the broiler diet on 22-42 days. apparent nutrient utilization [12]. Tang Maoyan et al. studied the effects of different combinations of compound enzyme preparations on the production performance of laying hens. The results showed that the egg production, egg production rate, average egg weight and feed-to-egg ratio of laying hens in the enzyme group with higher NSp enzyme activity were significantly better than those in the enzyme group. The control group (p0.05), while in the compound enzyme group with higher amylase content, the egg production of laying hens decreased and the feed-to-egg ratio increased. Whether the compound enzyme was added or not had no significant effect on their feed intake (p0.05 )[13]. It shows that the improvement of animal production performance by enzyme preparations is also related to the type of enzyme preparations. In terms of improving nitrogen and phosphorus utilization, Su Zifeng et al. studied the effects of the combination of compound non-starch polysaccharase and phytase on the growth performance and nitrogen and phosphorus digestibility of broilers. The results showed that adding compound NSp enzyme preparation and adding compound NSp enzyme preparation at the same time With phytase, the ground body weight and average daily weight gain of broiler chickens were significantly higher than those of the control group (p0.05). At the same time, the true nitrogen digestibility of broiler chickens in the compound NSp enzyme preparation and phytase group was significantly higher than that of other test groups (p0.05). 05), there was no significant difference in the apparent digestibility and true digestibility of total phosphorus in broiler chickens between the phytase group and the compound NSp enzyme preparation and phytase group (p0.05), but both groups were significantly higher than the control group. and only added NSp enzyme preparation group (p0.05) [14]. Studies have shown that the combined use of complex NSp enzyme preparations with complete enzymes and high activity and phytase can more effectively improve the growth performance of broiler chickens, improve the utilization of feed phosphorus, and coordinately reduce the pollution of nitrogen excretion.
In terms of apparent utilization rate and metabolizable energy, Wang Minghai et al.’s experiments showed that when 0.1% of the complex enzyme preparation was added to the corn-soybean meal diet for broilers, the energy difference between the groups was not significant (p0.05); The net protein utilization rate of the control group increased by 8.56% (p0.05); the amylase activity, protease activity and protease activity of the 20-day-old broilers in the test group were significantly higher than those of the control group (p0.05); the 20-day-old and The serum urea nitrogen of the 35-day-old test group was significantly higher than that of the control group (p0.05) [15]. It shows that adding enzyme preparations can improve the utilization rate of net protein and enhance the activity of some digestive enzymes. Liu Qinghua et al. reported that after adding 0.25gkg-1 of complex enzyme preparations to the diet of yellow-feathered roosters, the apparent utilization rate, apparent metabolizable energy and true metabolizable energy of organic matter were significantly different from those of the control group, and the apparent utilization rates were respectively increased. The apparent metabolizable energy and true metabolizable energy increased by 2.23%, 3.06%, 5.58%, and 7.25% respectively (p0.05) [16]. Yin Zhaozheng et al. replaced corn diet with high gluten plus enzyme in the diet of AA chicks. The results showed that compared with the high gluten plus enzyme group, the daily feed intake and feed weight ratio of the corn group were reduced by 4.44% (p0.05) and 0.05 respectively. 5.91% (p0.01); compared with the high-bran control group, the feed intake of the high-bran enzyme group increased by 4.66% (p0.05), the daily weight gain increased by 9.79% (p0.01), and the feed-to-weight ratio decreased. 4.76% (p0.01); compared with the high-gluten-added enzyme group, the abdominal fat rate of the corn group increased by 47.76% (p0.01), and the liver weight rate decreased by 15.92% (p0.01); Compared with the bran group, the breast muscle rate and liver weight rate increased by 6.16% (p0.05) and 22.52% (p0.01) respectively, and the serum uric acid (UA) content, serum alkaline phosphatase activity and serum phosphorus decreased by 36.11% respectively ( p0.01), 23.34% (p0.01) and 17.00% (p0.05), serum cholesterol and serum triglyceride levels increased by 15.90% (p0.01) and 20.22% (p0.05) respectively, serum T3 content It increased by 58.47% (p0.05), insulin content increased by 52.37% (p0.01), and insulin-like growth factor I increased by 56.50% (p0.01) [17]. Liu Yazheng et al. added different levels of complex enzymes to the basic diet of AA broilers. The results showed that adding different proportions of enzyme preparations increased the apparent digestibility and energy utilization of hemicellulose by 4.3 to 9.4 and 1.5, respectively, compared with the control group. ~2.1 percentage points [18]. Yi Zhonghua et al. added phytase 500pTUkg-1 to the low-phosphorus and low-protein diet of AA broiler roosters, and added phytase 500pTUkg-1 + compound digestive enzyme 0.5gkg-1 to the low-phosphorus and low-protein diet. The results showed that phytase The addition of acidase or phytase + complex enzyme significantly increased the daily weight gain and daily feed intake of broiler chickens (p0.05), reaching or even tending to exceed that of the ordinary control group (p0.05), and significantly increased the nitrogen and phosphorus levels of broiler chickens. Utilization rate (p0.05), significantly reducing nitrogen and phosphorus emissions [19].
2.1.2 Laying hens
Adding an appropriate amount of enzyme preparations to the diet of laying hens will help the chickens absorb and utilize protein and improve production performance. Liu Xiangan's research found that after adding complex enzyme preparations to mixed meal-type diets such as rapeseed meal and cottonseed meal, the egg production rate, feed-to-egg ratio and economic benefits can reach or approach the level of soybean meal-type diets, and achieve good economic benefits. [20]. Wang Jiqiang et al. studied the effects of adding different levels of enzyme preparations to wheat-based diets on the production performance of laying hens. The results showed that adding 0.1% enzyme preparations to the wheat-based diet for laying hens can significantly improve the nutrient utilization of wheat and improve the production performance of laying hens. , its effect is better than that of the corn basal diet group [21]. The research results of Niu Zhuye et al. also show that adding 0.1% of complex enzyme preparations to the wheat-based diet of laying hens can significantly improve the production performance of laying hens (p0.05), and reduce the rate of broken eggs and the rate of soft eggs [22 ].
In terms of replacing the conventional basal diet of laying hens and adding enzyme preparations to study the production performance of laying hens, Wang Xiuqi and others reported that the proportion of wheat in the basic diet was 30% and 0.1% xylanase was added. Compared with the control group, the egg production rate increased by 6.17%, the average egg weight increased by 5.24%, and the feed-to-egg ratio decreased by 11.30%. The differences were extremely significant (p0.01), but there was no significant difference in feed consumption (p0. 05)[23].
Lin Dongkang replaced 30% of the corn in the diet with wheat and Huafenase to feed laying hens. Studies have shown that the enzyme preparation increased the feed conversion rate by 2.9% to 3.3% and the egg production rate by 1.3%. %~2.1%, but the difference is not significant (p0.05) [24]. Wang Minghai added 1kgt-1 of complex enzymes to the basic diet of commercial generation Luoman laying hens. The results showed that adding complex enzymes to the feed of laying hens can significantly increase the egg production rate (p0.05) and have an impact on egg production rate and feed utilization. The effect is significant with the improvement of efficiency; the eggshell thickness of the test group is 5.7% higher than that of the control group, the difference is significant (p0.05), the Haugh unit is increased by 11.05, the difference is significant (p0.05), and the protein viscosity is significantly increased (p0.05 )[25].
2.2 Goose
Goose is an omnivorous poultry, and its digestibility of grass crude fiber can reach 40% to 50%. The gizzard pressure of geese is 100% greater than that of chickens, and it can effectively Lysens plant cell walls, making them easier to digest. In addition, the digestive tract of geese is 1000% longer than the body, while that of chickens is only 700%. The alkaline environment in the small intestine of geese can dissolve fiber, so geese have a particularly strong ability to absorb nutrients from pasture.
Enzyme preparations can relieve the anti-nutritional effects of beta-glucan in feed, increase the activity of amylase in small intestinal chyme, and enhance the digestion and absorption of carbohydrates and other nutrients. Ai Xiaojie et al. fed barley (45%) basal diet to study the effect of crude enzyme preparations on the digestive enzymes and pH of goslings' pancreas and small intestine chyme. The test results showed that adding crude enzyme preparations to goslings' basal diet At 0.1%, the amylase activity of duodenum, jejunum and ileum chyme was 31.84%, 59.94% and 21.08% higher than that of the control group, and the differences were extremely significant (p0.01). The pH of chyme in each section of the small intestine decreased significantly. (p0.05), indicating that after adding enzyme preparations, the feed conversion efficiency is improved and is more conducive to the growth of goslings [26]. Pei Xiangyuan et al. studied the impact of cellulase on the production performance of geese by adding different amounts of cellulase to the goose diet. The results showed that when 0.75% cellulase was added, the average daily weight gain of the geese in the test group increased by 8.9%, and the feed consumption It decreased by 5.1%~7.8%, while the protein digestibility increased by 5.3%. When the increase in enzyme reached 1.75%, the crude fiber digestibility increased by 5%, the dry matter digestibility increased by 13.6%, and the protein digestibility increased by 15% compared with the control group. , all reached the significant level (p0.05) [27]. Liu Changzhong et al. used in vitro digestion test methods to study the in vitro digestibility and reducing sugar production of crude protein, crude fiber, crude fat, crude ash, dry matter and amino acids by adding 0.2% and 0.4% NSp enzyme preparations to the basal diet of geese. The results showed that NSp enzyme 0.2% and 0.4% improved reducing sugar production, crude protein, crude ash in vitro digestibility, and amino acid in vitro digestibility to varying degrees [28]. This shows that enzyme preparations, especially cellulose enzyme preparations, play an important role in increasing the daily weight gain and feed return of geese.
2.3 Duck
Enzyme preparations can improve the production performance of ducklings, increase daily weight gain and reduce feed-to-weight ratio. Weng Run et al. found that adding 0.18gkg-1 of complex enzyme preparations to mixed meal-type diets at different proportions to feed Muscovite ducks aged 3 to 8 weeks, compared with the control group with conventional diets, the feed conversion rate, Both protein and energy digestibility are improved [29]. Wang Ye's test showed that for meat ducks of the same breed aged 0 to 45 days, the daily weight gain and feed weight of the enzyme-added group were improved by 6.91% and 6.71% respectively compared with the enzyme-free group, with significant differences (p0.05); the survival rate of enzyme-added group also increased by 0.43% compared with the group without enzyme. Although the difference was not significant, there was a trend of improvement [30]. Lu Minzhi et al. added enzyme preparations to the diet of Xianhu No. 3 meat ducks. The results showed that the average weight of each group of ducks at hatching and at the end of the 7-day pre-test was not significantly different (p0.05); at 21 days of age, the weight of the test group increased by 13.4% compared with the control group, and the difference was significant (p0.05). p0.05); in the two growth stages of 8 to 49 days and 0 to 49 days, the feed weight of the two experimental groups was significantly reduced by 4.55% and 4.70% respectively compared with the control group (p0.05) [31]. This is slightly different from Gao Shudong’s conclusion, and it is speculated that the reason may be related to the breed and age of the ducklings [32].
Yu Lu et al. used corn-soybean meal-mixed meal diets added with compound enzyme preparations to study the impact of compound enzyme preparations on the production metabolism of meat ducks. They found that compound enzyme preparations can increase the daily weight gain, The metabolic rate of feed dry matter, energy and crude protein was significantly increased (p0.05), and the digestibility of crude fiber was improved, but the difference was not significant (p0.05) [33]. When Huang Huangming et al. studied the effect of adding enzyme preparations to the feed on the nutrient metabolic rate of Cherry Valley ducks, they found that the average metabolic rate of dry matter and crude protein in the group adding compound enzyme preparations to the diet was significantly different from that of the control group (p0.05 ), increased by 6.57% and 3.09% respectively, and the average metabolic rate of crude fiber increased by 3.73%, but the difference was not significant (p0.05) [34].
Hu Zhijun et al. reported that by appropriately reducing the dietary energy level and using appropriate enzyme preparations in the production of commercial meat ducks, the daily weight gain, daily feed intake and feed conversion rate of meat ducks can all reach or exceed Normal nutritional level value, while the feed-to-weight ratio was significantly reduced (p0.05) [35].
In the production of laying ducks, adding enzyme preparations can improve the production performance of laying ducks and increase the egg production rate and fertilization rate. Sun Shuxia et al. studied the impact of enzyme preparations on the production performance of Muscovy ducks. The experimental group added a certain proportion of enzyme preparations to the basic diet and reared it under the same conditions for 56 days. The results showed that the egg production rate of the experimental group increased by 8.91% compared with the control group. %, the fertilization rate increased by 8.27%[36]. He Jian et al. studied the effects of reducing the dietary nutritional level of laying ducks and adding enzyme preparations on the production performance of laying ducks. The test results showed that the dietary nutritional level was reduced, and adding compound enzyme preparations could improve the egg production performance of laying ducks. When the nutritional level was lower than normal, He Jian et al. After adding 9% enzyme preparation, the egg production rate increased by 3.4%, which was extremely significant compared with the control group (p0.01). The feed intake increased by 7.5% compared with the control group, but the difference in egg weight between the groups was not significant (p0.01). p0.05)[37].
3 Summary
As a highly efficient, non-toxic and side-effect-friendly green feed additive, enzyme preparations can not only improve the digestibility and utilization of feed, but also improve animal production. It can also reduce the excretion of nitrogen and phosphorus in livestock and poultry excrement, and reduce the pollution of water and soil. Therefore, enzyme preparations have very broad application prospects in animal feed and animal production.