Good prospect of soybean husk application in feed industry

Introduction: with the progress of soybean oil production technology and the increase of market demand for high-quality soybean meal, soybean oil production enterprises in developed countries are transforming the leach process with skin into the leach process without skin The soybean meal produced by this technology has high protein content and stable quality At present, some large soybean processing enterprises in Jiangsu, Hebei, Shandong, Jilin, Liaoning and other provinces in China have adopted the technology of peeling and leaching, and have received good benefits Soybean husk (SH) is a main by-product of peeled soybean meal produced by peeled extraction With the increase of SH production, it is of practical significance to use sh as feed source reasonably and effectively for feed industry 1 The chemical composition and digestibility of SH is a very thin skin wrapped around the soybean, accounting for 8% of the weight and 10% of the volume of the whole soybean, mainly composed of plant fiber or cell wall, almost without starch Based on 90% dry matter, SH crude fiber is 38%, neutral detergent fiber is 63%, acid detergent fiber is 47%, but its lignin content is only 1.8% The crude protein of SH was 13%, the calcium and phosphorus were 0.49% and 0.21%, respectively (Preston, 1999; NRC, 1989) Due to the difference of raw materials and processing technology, the chemical composition of SH also changed to a certain extent The variation range was: neutral washing fiber 57% - 73.7%, crude egg 9% - 16.5% (Kung and Lin, 1997) Studies on the digestibility of SH mainly focus on ruminants Due to the low degree of lignification of SH cellulose, ruminants can digest more than 90% of their dry matter (quicke et al., 1959; Hsu et al., 1987; belyea, 1989), and the digestibility can reach 95% (klopfenstein and Owen, 1987) The results showed that sh could promote the digestion of cellulose in diet, because: 1) sh cellulose had a high digestibility; 2) sh could stimulate the rapid growth of some microorganisms which decompose cellulose in rumen fluid and enhance their activity of degrading cellulose; 3) sh had a positive interaction effect on the digestion of dietary fiber (Cunningham et al., 1993) ; Nakamura et al., 1989) 2 Application of SH in feedstuff 2.1 application of SH in feedstuff of dairy cattle ruminants usually limit their energy intake by only eating low-quality roughage The common way to improve the energy intake is to supplement the cereal energy feed However, the rapid fermentation of a large amount of starch rich cereal feed in rumen will lead to the rapid reduction of pH value of rumen fluid and the disorder of microbial flora, which will affect the digestion of dry matter and crude fiber of feed A large number of literatures have reported that there is no adverse effect on feeding sh to ruminants who eat low-quality roughage Because of the high content of SH digestible fiber, its energy value is also high The net energy production of SH is 7.4mj/kg, while that of corn, wheat bran and oats is 8.2, 6.7 and 7.4mj/kg, respectively, which indicates that sh can replace some energy feed components in the diet of dairy cows Therefore, according to the effective energy value, SH is considered to be a larger volume of refined feed, rather than coarse feed CORAD and Hibbs (1961) studies confirmed that the substitution of SH for 63% oats in the concentrate mixture of dairy cows had no effect on the corrected milk yield of 4% milk fat ratio of dairy cows MacGregor et al (1976) in the experiment of alfalfa silage and mixed concentrate as cow diet, it was found that sh replaced 27% and 48% corn respectively in the concentrate of cow, and there was no significant difference in milk yield between the treatment groups Kohlmeier et al (1996) and Kung et al (1997) pointed out that the substitution of SH for part of the grain feed in the mixed concentrate of dairy cows had no obvious negative effect on the milk yield and milk yield efficiency, or even increased Meng Qingxiang et al (2000) showed that compared with the control group, when sh was used to replace 25% and 50% corn and wheat bran in the concentrate of dairy cows, there was no significant difference in daily milk output, 4% milk fat ratio corrected milk output, milk protein, lactose, fat free solids and milk feed conversion rate of dairy cows At the same time, the feed cost per kilogram of standard corrected milk was reduced by 0.045 yuan and 0.057 yuan respectively There are also some experiments using SH to replace corn in the concentrate of dairy cows The results show that with the increase of SH replacement ratio, the milk yield of dairy cows decreases gradually, but the milk fat rate increases gradually, and the corrected milk yield of 4% milk fat rate is basically unchanged The results of a large number of comprehensive experiments show that sh can effectively improve the milk fat rate and have no negative effect on the milk yield and feed conversion efficiency by replacing less than 30% of the cereal energy diet (corn, barley, oats, etc.) in the mixed concentrate of dairy cows, so it is feasible to replace the mixed concentrate of ruminants with sh 2.2 application in beef cattle feed for growth and fattening beef cattle, the lower the level of dietary concentrate, the higher the nutritional value of adding SH in the feed The same amount of corn and sh, SH and corn nutrition value are similar to each other, and the production performance of beef cattle is similar (Anderson et al 1989; kohlmeier et al 1996; Kung et al 1997) The results showed that when the level of feed concentrate was lower than 25%, the nutritional value of SH was equal to that of corn When the level of feed concentrate was between 25% - 50%, the feed value of SH was equal to 80% - 95% of corn When the level of feed concentrate was higher than 50%, the feed value of SH was equal to 67% - 80% of corn (LUDDEN et al., 1995) According to the actual situation of beef cattle raising in China, it can not only improve the growth speed of beef cattle, but also effectively reduce the cost by feeding proper amount of SH to shelf cattle and grazing cattle 2.3 Application in single stomach animal feed: due to the decrease of feed intake on a certain day, the retention time of feed in the hindgut of digestive tract is prolonged, and the ability of digesting crude fiber is greatly improved compared with that of growing finishing pigs Reese et al (1997) pointed out that pregnant sows need to limit energy intake to prevent obesity, and it is more appropriate to feed a diet with high fiber and low energy concentration Their results showed that the number of weaned piglets per litter increased by 0.5-0.7 by adding 20% sh to the feed of pregnant sows At present, it is believed that the addition of SH in feed can significantly increase the number of piglets weaned in sows, which may be related to the high concentration of isoflavone in SH, and the effect of isoflavone with similar estrogen on animal reproductive performance There are few reports on the application of SH in feed for growing finishing pigs and poultry Kornageay (1978) reported that sh was used to replace corn in the diets of growing finishing pigs with the initial weight of 22 kg When the amount of SH was lower than 12%, it had no effect on the growth rate of pigs, but the feed conversion efficiency decreased by 6% When the amount of SH was increased to 24%, the growth rate and feed conversion efficiency of pigs decreased by 6% and 8%, respectively Chee et al (1989) compared the nutritional value of SH and wheat bran in 160 finishing pigs and 72 growing pigs The results showed that there was no significant difference in feed conversion efficiency, production performance, eye muscle area and back fat thickness between the two groups when 10% sh was added to the feed (heat treatment reduced the urinary enzyme activity to 0.1 unit) and 10% wheat bran, respectively Meng Qingxiang et al (1999) carried out the experiment of replacing grass meal in the diet of meat rabbit with sh the results showed that replacing 25% and 50% grass meal with SH could improve the health status and speed of weight gain of meat rabbit Meng Qingxiang et al (2000) conducted a test on steaming SH instead of corn and wheat bran in the rabbit diet The results showed that the SH substitution level of 25% and 37.5% had no significant effect on the growth performance, incidence rate and mortality of the rabbits In addition, SH can also be used in pet feed which needs to limit energy intake It can not only prevent pet from being too fat, but also accelerate the flow speed of feed in its digestive tract, reduce the production of toxic metabolites (such as ammonia and amine) in the digestive tract, so as to improve the health status of animals 3 Conclusion a large number of experiments have proved that the feed value of SH is equal to that of corn in the diets of cows and shelf cattle The feed value of SH was lower than that of corn in the diet of fattening cattle SH is an ideal raw material for Energy Limited diet of pregnant sows, and it is also beneficial to increase the number of weaned sows Because SH has high crude fiber content and urease activity, it may have some anti nutritional effects It should be used carefully in the feed of single stomach animals such as pigs and chickens, and the proportion should not be high.