Effects Of Continuous Supplementation With Yeast Culture In Prepartum Dietary On Lactation Performance And Rumen Fermentation Function In Dairy Cows

Yeast culture products can not only increase the feed intake of dry material,stabilize the rumen environment,but also improve the milk yield and milk quality of dairy cows,and there is no drug residue problem similar to antibiotics.At present,there are numerous reports on the effect of yeast cultures on animal performance,but data from comprehensive studies of perinatal and lactation of dairy cows are scarce.This experiment studied the influence and existence mechanism of yeast cultures on feed intake,apparent digestibility of nutrients,milk yield,milk quality,blood indexes,rumen fermentation parameters and microbial flora,aiming to lay a foundation for the rational application of yeast cultures.This trial used a univariate randomized trial design with 30 preperinatal Holstein cows with similar parity,body condition and body weight,randomly divided into 2 groups of 15 each.The control group was fed a basal diet,and the test group was fed a basal diet + 120g/d yeast cultures.The cows were fed in the preperinatal period and ended at 90 d postpartum with the test period of 135 d.Dairy cow feed,stool,blood samples,milk samples and rumen fluid were collected regularly during the trial.The study results show that the following:1.Feeding yeast cultures had no significant effect on the apparent digestibility of crude protein,crude fat and phosphorus,but dry material intake increased significantly from 30 d to 60 d postpartum(P<0.05),that of neutral and acidic washed fibers increased significantly at 60 d(P<0.05)and calcium at 15 d and 60 d(P<0.05).2.Feeding yeast culture had no significant effect on most serum biochemical indexes,serum Ig A and Ig M,but serum concentrations of catalase and triiodothyronine increased significantly at 15 d and 60 d postpartum(P<0.05),total protein,albumin,immunoglobulin G,glucose,heat shock protein-70 and tetraiodothyronine at 60 d;and concentrations of malondialdehyde,BUN and nonesterified fatty acids decreased at 60 d(P<0.05).3.Feeding yeast cultures had no significant effects on milk protein rate,lactose rate and urea nitrogen,but milk production increased from 30 d to 60 d postpartum(P<0.05)and milk fat rate at 30 d and 60 d(P<0.05);somatic cell number decreased at 30 d(P<0.05)and extremely decreased at 60 d(P<0.01).4.Feeding yeast cultures had no significant effect on the mean p H and volatile FA concentrations,but the concentration of propionate,aminopeptide nitrogen and microbial protein in the rumen increased significantly at 90 d postpartum(P<0.05).No significant effect on gene function and bacterial community phenotype in the rumen(P>0.05).The coverage of intragastric species in both groups was greater than 99%,and the difference between Shannon index and Observed features index was not significant(P>0.05).At the phylum level,The relative abundance of Proteobacteria and Cyanobacteria in dairy cows was significantly increased(P<0.05);The relative abundance of Bacteroidetes and Verrucomicrobia was significantly increased(P<0.01);The relative abundance of Planctomycetes and Spirochaetes was significantly reduced(P<0.01).At the genus level,The relative abundance of Butyrivibrio,Lachnospiracea,Brevundimonas,and Papillibacter increased significantly(P<0.05);The relative abundance of Succinivibrionaceae,Fibrobacteria,and Bacteroidia was significantly increased(P<0.01);The relative abundance of Anaerovibrio and Ruminobacte was significantly reduced(P<0.05);The relative abundance of Succiniclasticum and Selenomonas was significantly reduced(P<0.01).In conclusion,the addition of yeast cultures in a certain proportion of dairy cows can improve their food intake and milk yield,enhance their antioxidant capacity and immunity,optimize the structure of the rumen bacterial community,and stabilize the internal environment of the rumen.