| Soybean residue is a by-product of soybean milk,tofu or soybean protein processed.It has high yield and low price,but it is difficult to preserve it well because of its high moisture content.Corn straw is an agricultural by-product with rich resources and contains high dry matter,but its high fiber content and poor palatability limit its application in animal feed.The mixed storage of soybean residue and corn straw can not only solve the problem of difficult preservation of soybean residue,but also improve the utilization rate of corn straw.Therefore,the optimal inoculation ratio was selected by measuring the p H and viable bacteria number of Lactobacillus plantarum,Brucella and Lactobacillus acidophilus;Then the biological characteristics and stress resistance of compound lactic acid bacteria and single lactic acid bacteria were evaluated;Finally,Mixed Silage of soybean residue and corn straw was carried out with compound lactic acid bacteria and cellulase,and its chemical composition,fermentation quality and effects on rumen fermentation characteristics of dairy cows were evaluated.Finally,the optimal mixed storage treatment group was fed to dairy cows,and the blood indexes,lactation performance and rumen fermentation of dairy cows were evaluated.This study is of great significance to improve the utilization of feed resources in China.Experiment 1: screening of proportion of compound lactic acid bacteria and Study on its biological characteristics and stress resistanceIn this experiment,Lactobacillus plantarum,Lactobacillus brucelli and Lactobacillus acidophilus extracted from naturally fermented corn silage were selected as fermentation strains,and 9 proportions were set up.The optimal proportion was determined by measuring the number of viable bacteria and p H.Then,the biological characteristics and stress resistance of compound Lactobacillus and single lactobacillus were evaluated.The results showed that the proportion of Lactobacillus plantarum,Lactobacillus brucelli and Lactobacillus acidophilus was 2:3:1,and the number of live bacteria was the highest and the p H was the lowest after 24 h.The p H of compound lactobacillus was the lowest at 24 h of activation,and the acid resistance,bile salt resistance and bacteriostasis of compound lactobacillus were higher than those of single Lactobacillus.Experiment 2: effects of adding lactic acid bacteria and cellulase on the effects of the chemical composition,mixed storage quality,microbial diversity of Soybean residue and straw.In this experiment,a single factor experimental design was adopted,and four treatment groups were set up,which were compound lactic acid bacteria(1×106 CFU / g,lab),cellulase(100 U / g,CE),compound lactic acid bacteria + cellulase(1×106 CFU + 100 u,lab + CE)and control group(CON).After 56 days of mixed storage,samples were taken and the chemical composition,fermentation quality,in vitro rumen fermentation and microbial diversity were determined.The results showed that the p H of lab and CE treatment groups were significantly lower than that of the control group(P<0.05),while the contents of lactic acid and ammonia nitrogen in each treatment group were significantly lower than that of the control group,and the lab + CE group reached the highest.The contents of neutral detergent fiber,acid detergent fiber and dry matter in LAB + CE treatment group were significantly lower than those in con group(P<0.05),while the crude protein was significantly higher(P<0.05).Compared with CON,the contents of total volatile fatty acids,acetic acid,propionic acid and butyric acid in the fermentation broth of each treatment group were significantly increased(P<0.05),and the LAB + CE treatment group reached the highest,while the ratio of acetic acid to propionic acid in lab group and lab +CE group decreased significantly(P<0.05).It can be seen that the addition of LAB or CE can improve the fermentation quality and in vitro rumen fermentation characteristics of soybean residue and corn straw,and the effect is the best when LAB and CE are added together.The results of principal component analysis showed that there were significant differences in bacterial composition among LAB group,CE group,LAB + CE group and CON group.The analysis of flora level showed that the content of lactic acid bacteria in LAB + CE group was significantly higher than that in other treatment groups(P< 0.05),while the content of Rahnella was significantly lower than that in other treatment groups(P< 0.05).Experiment 3: effect of Mixed Silage of soybean residue and corn straw on blood index,lactation performance and rumen fermentation of dairy cowsIn this experiment,24 healthy Holstein cows with body weight(mean ± standard deviation;624 ± 14.4 kg),lactation days(112 ± 4.2 d)and similar parity(milk yield 31.8 ± 1.73 kg;both mean ± standard deviation)were selected for this feeding experiment.Each cow was raised in a separate fence(2 m× 2.5 m).After two weeks of adaptation,the cows were randomly divided into two treatment groups according to body weight and milk yield:(1)untreated basic diet group(control group);(2)Mixed Silage treatment group(treatment group)for 8 weeks.Compared with the control diet group,the concentration of blood glucose and globulin in the blood of dairy cows could be significantly increased in the Mixed Silage diet group of soybean residue and straw(P <0.01).At the same time,the non esterified fatty acids in the Mixed Silage diet group were significantly higher than those in the control diet group(P< 0.01).Compared with the control group,the Mixed Silage diet group could significantly reduce the blood cholesterol concentration(P< 0.05),and the Mixed Silage diet group could significantly reduce the blood alanine aminotransferase concentration(P< 0.05).Compared with the control diet,the Mixed Silage diet group could increase the concentration of alkaline phosphatase in blood(P < 0.05).In addition,the levels of aspartate aminotransferase and triglyceride in the Mixed Silage diet group were not significantly lower than those in the control group,but there was a downward trend(0.05 < p <0.1).The rumen p H of Holstein cows fed Mixed Silage diet was not significantly lower than that of the control group(P> 0.05).At the same time,compared with the control group,the concentrations of NH3-N(P< 0.01),TVFA(P< 0.01)and acetic acid(P< 0.01)in rumen of Holstein cows fed Mixed Silage diet group were significantly increased.However,there was no significant difference in propionic acid(P= 0.12).Compared with the control group,the milk yield of dairy cows in the Mixed Silage group of soybean residue and straw was significantly increased(P= 0.017).At the same time,the milk protein and milk fat corrected milk in the Mixed Silage group were significantly higher than those in the control group(P< 0.01).Compared with the control group,the Mixed Silage group could significantly increase the number of somatic cells of dairy cows(P =0.01).To sum up,the following conclusions were drawn from this study:(1)Through screening,the best compound ratio of the three strains of lactic acid bacteria is 2:3:1(Lactobacillus plantarum: Lactobacillus brucelli: Lactobacillus acidophilus).The p H of the compound lactic acid bacteria is the lowest when activated for 24 hours,and the acid resistance,bile salt resistance and bacteriostasis of the compound lactic acid bacteria are higher than those of a single strain of lactic acid bacteria.(2)The mixed addition of compound lactic acid bacteria and cellulase can improve the mixed storage quality of soybean residue and corn straw,and improve the rumen fermentation of dairy cows in vitro.(3)Soybean residue mixed with straw silage increased the concentration of ammonia nitrogen,total volatile fatty acids,acetic acid and propionic acid in the rumen of dairy cows,increased blood glucose globulin concentration and decreased β-hydroxybutyric acid,non-esterified fatty acids and ghrelin concentrations,and improved the rumen fermentation environment. |
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