Study On Changes Of Rumen Fermentation Parameters And Microbial Diversity In Weaning Calves

In this study,12 healthy 50 day old Chinese Holstein calves with similar body weight were selected.The experiment lasted for 31 days(10 days before weaning and 21 days after weaning).From 55 days old,the calves were stimulated to increase the feed intake and alfalfa hay intake by 20%of mixed milk per day.The rumen fluid and blood were collected on the day of weaning,7 days,14 days and 21 days after weaning.The purpose of this experiment is to study the diversity of rumen microflora after weaning by high-throughput sequencing technology,to explore the process of rumen microflora establishment and self balance,to preliminarily study the changes of rumen fermentation parameters,blood biochemical indicators,immune and intestinal permeability indicators after weaning,so as to provide theoretical basis for calf production management and nutrition regulation.The main test results are as follows:Experiment 1:To study the changes of rumen fermentation parameters after weaning.With the increasing of age,the utilization of NH3-N by rumen microorganisms increased gradually,and MCP increased gradually.Experiment 2:To study the changing rule of rumen bacterial flora after weaning of calves.After weaning of calves,the diversity of rumen bacterial flora decreases,and as the age increases,the diversity of the bacterial flora gradually recovers and increases.As the age increases,the abundance of Bacteroidetes increases significantly(P<0.05),The abundance of Prevotella 7 increased significantly(P<0.05).The concentration of total volatile acid,acetic acid,propionic acid and urea nitrogen is significantly related to the composition of rumen bacterial colonies.Among all environmental factors,the level of volatile acid may be the key factor affecting the rumen bacterial coloniesExperiment 3:To study the changes of rumen fungal flora after weaning.With the increase of age,the abundance of Basidiomycota increased significantly(P<0.05),and the abundance of Torulaspora increased significantly(P<0.05).Among all environmental factors,the concentration of volatile acids may be the key factor affecting rumen fungal colonies.