Experimental Study On The Application Of Fermented Soybean Residue In Fattening Pigs

Soybean residue is a by-product produced after the processing of soybean products,and the annual output of our country is huge.Soybean residue has high nutritional value and is considered to be a protein feed with great potential.However,as feed in pig breeding,it is difficulty to collect,store and process,and has poor taste and beany smell.The palatability and nutritional value of soybean dreg can be improved through microbial fermentation technology,which is helpful to solve the problems in the use of fresh soybean dreg.It is an economical and environmentally friendly choice to use it in fattening pig breeding,which can not only optimize the feeding cost but also avoid the waste of soybean dregs.In this study,different levels of fermented soybean residue were added into the basal diet of healthy finishing pigs with similar age,body condition and body weight,in order to explore the effects of fermented soybean residue on growth performance,serum biochemical indices and intestinal microflora of finishing pigs,and to lay a theoretical and technical foundation for the application of fermented soybean residue in the production of fattening pigs.Test 1:Effect of fermentation on nutritional components of soybean residueIn this experiment,soybean residue and bran were used as raw materials,mixed in the ratio of 2:1 and fully stirred as pretreatment materials.The fermentation bacteria liquid was diluted in proportion,and 2 kg water was added for every 100 m L of fermentation agent as the starter,and evenly sprayed on the surface of the pretreatment material.The water content was controlled at about 60%,and the liquid was loaded into the fermentation barrel and compacted,and the temperature was about 20℃for sealed fermentation for 7 d-60 d.Samples were taken at the 0th,7th,15th,30th,45th and 60th days of fermentation,and detect the content of conventional nutrie.The results showed that the water content of fermented soybean residue decreased significantly and the ash content of fermented soybean residue increased significantly after fermentation（P<0.05）.After 0,7,15,30 and 45 d of fermentation,the crude fat content of soybean dregs did not change（P>0.05）,but increased significantly after 60 d of fermentation（P<0.05）.After 45 d of fermentation,the content of crude fiber in soybean residue increased significantly,and the content of crude fiber decreased significantly at 60 d of fermentation compared with 45 d,but there was no significant difference from that at 7,15 and 30 days of fermentation.The crude protein content of soybean dregs was significantly increased at 7 d,and extremely significantly increased at 15 d,reaching the highest value.The crude protein content at 15 d was significantly higher than that at other 4 days（0,7,30,45,60 d）.Test 2:Effects of fermented soybean residue on growth performance and blood biochemical indexes of fattening pigs.The preparation method of fermented soybean residue in this experiment is the same as that in the previous experiment.The temperature is about 20℃and sealed fermentation for 15 days.It is used for feeding fattening pigs.Forty-five healthy local black pigs at 60 days of age with an average body weight of 31 kg were randomly divided into control group,15%fermented soybean residue group and 25%fermented soybean residue group with 3 replicates per group and 5 pigs per replicate.The control group was fed with basic diet,the 15%fermented soybean residue group was fed with basic diet supplemented with 15%fermented soybean residue,and the 25%fermented soybean residue group was fed with basic diet supplemented with 25%fermented soybean residue.The experiment lasted for 60 days and was fed twice a day.The daily feed intake of each group was recorded every day and the pigs were weighed every 15 days to compare the differences of initial average weight,final average weight,average daily gain and actual weight gain of the three groups.Blood samples were collected from ear margin vein in the morning of 0,30 and 60 days,respectively,to detect the changes of immune indexes（Ig A,Ig G）,complement C₃and C₄,and antioxidant indexes（GSH-Px,SOD,CAT,MDA）in serum.The results showed that the final average weight,average daily gain,actual gain and gross profit of 15%fermented soybean residue group and 25%fermented soybean residue group were significantly higher than those of control group（P<0.05）.Compared with the initial stage of feeding,with the extension of feeding time,the contents of Ig G,complement C₃and C₄in serum of the control group decreased significantly,the contents of Ig A,complement C₃,C₄and MDA decreased significantly and the content of CAT increased significantly in serum of pigs added with 15%fermented soybean residue（P<0.05）,the contents of Ig A,complement C₃,complement C₄,GSH-Px and MDA in serum of 25%fermented soybean residue group decreased significantly（P<0.05）.However,the contents of Ig A,complement C₃,complement C₄,CAT,SOD,GSH-Px and MDA in serum of pigs in 15%fermented soybean residue and 25%fermented soybean residue group had no significant differences compared with the control group at the same time（P>0.05）,and the Ig G content in 25%fermented soybean residue group was significantly higher than that in the control group after feeding for 60 days（P<0.05）.Test 3:Effect of fermented soybean residue on intestinal flora of fattening pigs.The preparation of fermented soybean residue,grouping of fattening pigs and dietary treatment are the same as above.At the end of the experiment,fecal samples of three groups of fattening pigs were collected,and the changes of intestinal flora of pigs were analyzed by 16Sr DNA high-throughput sequencing.Feeding 15%and 25%fermented soybean residue increased the species richness and diversity of intestinal flora,and the richness of beneficial bacteria.Compared with the control group,the alpha and beta diversity of 15%and 25%fermented soybean dregs groups were significantly different.Firmicutes and Bacteroidetes were the dominant bacteria in the three groups.The abundance of Lactobacillus and Rikenellaceae＿RC9＿gut＿group in intestine of pigs in 15%fermented soybean residue group was significantly higher than that in control group and 25%fermented soybean residue group.Alloprevotella richness in 15%and 25%fermented soybean dreg groups was lower than that in the control group.The abundance of Roseburia and Clostridium in 25%group was higher than that in 15%fermented soybean residue group.LEf Se analysis showed that there were 13 characteristic bacteria genera in the control group,13 characteristic bacteria genera in the 15%fermented soybean dregs group and 4 characteristic bacteria genera in the 25%fermented soybean dregs group.In conclusion,fermented soybean dregs can improve the content of crude protein,crude fat,crude fiber and other nutrients in soybean dregs,and prolong the preservation time of soybean dregs.Feeding fattening pigs with fermented soybean residue can promote the growth and development of pigs,improve immunity and antioxidant capacity,and reduce feeding cost.Meanwhile,fermented soybean dregs increased the species richness and diversity of intestinal microflora,and the lactobacillus abundance in 15%fermented soybean dregs group was higher than that in control group and 25%fermented soybean dregs group.The increase of the abundance of beneficial bacteria in the intestinal tract is conducive to the improvement of the intestinal microbial environment of pigs to a certain extent,maintain the balance of intestinal flora,and promote the growth and development of pigs.