| Soybean meal is a kind of high-quality vegetable protein feed,but it contains various anti-nutritional factors.Microbial fermentation technology can improve the nutritional value of soybean meal and degrade anti-nutritional factors.The purpose of this experiment is to study the effects of fermented soybean meal on production performance,rumen microorganisms and physiological metabolism of dairy cows in mid-lactation,and to provide reference for the application of fermented soybean meal in dairy cow production in the future.In this experiment,24 lactating cows with similar lactation period(mid-lactation),milk yield(20.3±3.4 kg),parity(1-2 births)and body weight(460±50 kg)were selected from Qingxi dairy farm of Nanshan animal husbandry co.,ltd.The control group was fed with common soybean meal diet,while the experimental group was fed with fermented soybean meal diet with free water and food intake.The pre-feeding period was 14 d and the normal feeding period was 40 d.Samples were collected at the last 7 d of the experimental period.The results are as follows:(1)Fermented soybean meal diet significantly reduced the dry matter intake of lactating dairy cows(P<0.05).The daily average milk yield,4% corrected milk yield and dry matter intake/daily milk yield of the experimental group had no significant difference compared with the control group(P>0.05).There was no significant difference in apparent digestibility of all nutrients in the experimental group(P>0.05).(2)The results of the study on milk composition,amino acids and fatty acids in milk show that there is no significant difference between the experimental group and the control group(P>0.05).Asp,Thr,Ser,Glu,Gly,Ile,Leu,Lys,Arg in the milk of dairy cows in the experimental group showed an increasing trend but not significant(0.05<P<0.1).His in milk of cows in the experimental group was significantly increased(P<0.05).Fermented soybean meal significantly increased C14:1 and C16:0 of milk chain fatty acids in the experimental group(P<0.01),and C17:0 and C18:0 significantly decreased(P<0.05).(3)In terms of serum biochemical indexes,the serum glutamic-pyruvic transaminase,glutamic-oxaloacetic transaminase,total cholesterol,high density lipoprotein and density lipoprotein cholesterol in the experimental group were significantly decreased(P<0.05),and the blood sugar showed a decreasing trend(0.05<P< 0.1).(4)In rumen fermentation,volatile fatty acids in the experimental group showed a decreasing trend(0.05<P<0.1);The ammonia nitrogen,p H,acetic acid,butyric acid,isovaleric acid and isobutyric acid in the experimental group had no significant difference(P>0.05).Propionic acid and pentanoic acid increased significantly(P<0.05).Acetic acid/propionic acid decreased significantly in the experimental group(P<0.05).(5)In rumen bacteria,Fibrobacter succinogenes and Selenomonas ruminantium in the experimental group were significantly increased(P< 0.01),Prevotella spp,Ruminobacter amylophilus,Ruminobacter flavefaciens,Total bacteria were significantly increased(P<0.05).;Simpson index was significantly higher than that of the control group(P<0.01).Shannon index and Coverage decreased significantly(P<0.05).(6)The rumen colony similarity between the experimental group and the control group is high.On the relative abundance of phylum level,Firmicutes tends to increase(0.05 <P<0.1),and Fibrobacterota decreases(P<0.05).In the relative abundance of genus level,Succiniclasticum in experimental group was significantly increased(P<0.05).The above results show that fermented soybean meal instead of soybean meal has no negative effect on dairy cow’s production performance and milk composition,and has certain promotion effect on umami amino acids in milk.Fermented soybean meal has some effects on rumen fermentation and rumen microorganisms but is not reflected in the apparent digestibility of nutrients.Fermented soybean meal,as a protein feed substitute,needs more experimental and verifications when applied to ruminant breeding. |
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