Variation Of Microbial Flora In Rumen And Regulation Of Microecofogic Preparation In Transition Period Dairy Cows

The transition period of a dairy cow is defined as the period from three weeks priorto calving to three weeks after calving. Feed consumption during the week beforecalving declines 30%, while feed intake during the first five weeks of lactation isinsufficient to meet the increasing energy demands of lactation. During this time,energy output in the form of milk exceeds energy input in the form of feed, which leadsto negative energy balance (NEB) or ketosis. The ratio of acetic acid, propionic acidand butyric acid generated in the rumen is affected by the type of forage, and the speciesand quantity of rumen bacteria. In the normal state, carbohydrates are fermented by avariety of bacteria in the rumen, and transformed into volatile fatty acids by thecorresponding enzymes. In ruminant animals, approximately 90% of the glucose issupplied by gluconeogenesis, with 50-60％of this being derived from propionate. It isimportant to investigate the relationship between composition of the bacterialcommunity and concentration of VFAs in the rumen during the transition period, or inthe case of ketosis, in dairy cows to identify strategies that might alleviate or avoidNEB and ketosis through regulation of microbial fermentation in the rumen. Inpresent study we analyzed the rumen microbiome composition of cows in the transitionperiod, cows with ketosis and non-perinatal cows using terminal restriction fragmentlength polymorphism (TRFLP) analysis of 16S rRNA genes and Quantitative PCR. Andbacteria metabolic engineering strategy and the change of rumen function are used asthe theoretical basis, and with the compound of propionic bacteria and yeast as thecore technology. This will open up a new way for the prevention and control for NEBin transition period cows.This test proved that transition and ketosis cows into a high-grain from alow-gtain diet, the amount of latic-producing baceria—lactobacillus and streptococcusbovis were significantly increase in the rumen, but the amount of propionic-ptoducingbaceria—selenomonas ruminantium and megasphaera elsdeniim were significantlyreduce in the rumen, lactic acid can not be fully catabolism, resulting in lowerconcentration of VFAs to promote a negative energy balance and ketosis disease.Screening the optimal yeast combination from Saccharomyces cerevisiae, Candida utilis, Burton pichia pastorios with Selenomonas ruminantium andMegasphaera elsdenii, a rumimal compound probiotics for negative energy balance intransition period cows was developed successfully. The probiotics could promote theuse of lactic acid by Saccharomyces cerevisiae, Candida utilis, Burton pichiapastorios combined with Selenomonas ruminantium and Megasphaera elsdenii, andincreased the concentration of propionic acid in vitro.When administered with the probiotics to the transition period cows with NEB orketosis, increased the ruminal amount of Selenomonas ruminantium, Megasphaeraelsdeniim, Fibrobacter succinogenes, cellulose decomposition bacteria and anaerobicbacteria; decreased the amount of Lactobacillus and Streptococcus bovis. Increasedthe concentration of VFAs in rumen; decreased the concentration of BHBA in serumof post-partum and ketiosis cows; increased the concentration of glucose in serum ofpost-partum and ketiosis cows.The health cows which were administered with the composite ruminal probioticsdisplayed no change of the blood biochemical index and clinical manifestation,indicating that the composite ruminal probiotics is safe,non-toxic and reliable fortransition period cows.