| In this study,20 healthy,similar-weight newborn Angus calves were randomly divided into two groups,with 10 replicates in each group and 1 cow in each replicate.The control group was fed pellets without any compound bacteria,while the experimental group was supplemented with 1%compound bacteria pellets(yeast,Bacillus subtilis,Lactobacillus plantarum,the viable count was 3× 108 CFU·g-1).The experimental period was 90 d,of which the pre-feeding period was 10 d and the positive trial period was 90 d.The pellet feed intake of the calves was recorded every day,and the calf was weighed on the 0th,30th,60th,and 90th days,and rumen fluid and blood were collected in the morning on the 100th day in a fasting state.The purpose of this experiment was to study the changes of calf rumen fermentation parameters,rumen flora structure,serum biochemistry,immunity,antioxidant,growth performance and other indicators,and to explore the establishment and self-regulation of rumen microorganisms by compound bacteria pellets.The regulation of growth and development of calves provides a theoretical basis for the application of compound bacterial pellets in Angus calves.The main test results are as follows:Experiment 1.Effects of compound bacterial pellet feed on rumen fermentation parameters and microbial community structure of calves:The content of MCP,Simposon index,Sobs index and Ace index in experimental groups were significantly higher than those in control group(P<0.05),Shannon index and Chao index were extremely significantly higher than those in control group(P<0.01).At the phylum level,the dominant phyla in the two groups were Mainly Bacteroidota and Firmicutes.Prevotellaceae_UCG-003 and Prevotellaceae_UCG-001 of experimental group were significantly higher than those of control group(P<0.05).Prevotella was the dominant genus in both groups,but the second dominant genus was different in the two groups:The experimental group was norank_f_Muribaculaceae,and the control group was Rikenellaceae_RC9_gut_group.The abundance of other genera was relatively higher than that of the control group.Experiment 2,the effects of compound bacterial pellet diet on serum biochemical indices,immune indices and antioxidant indices of calves:the contents of AST,β-Hb,CAT,GSH-Px and TAOC in serum of experimental group were significantly higher than those in control group(P<0.01).The content of IL-1β,IL-2,IL-4,IL-6,TNF α and MDA in control group was significantly higher than that in experimental group(P<0.01).Experiment 3:The effects of compound pellet feed on the performance of calves:compound pellet feed could significantly increase the average dry matter intake of calves at one months two months and three months of age(P<0.05),significantly reduce the ratio of feed to gain of calves at one month,two months and three months of age(P<0.01),and increase the breeding benefit by 4.62%.In conclusion,compared with calves without compound bacteria,compound bacteria pellets can improve the rumen fermentation environment of calves,increase the richness and diversity of rumen flora,and affect the community composition at the phylum and genus levels;It can significantly improve the biochemical,immune and antioxidant properties of calf serum;Increase feed intake,average daily gain,reduce feed to weight ratio and promote the growth and development of calves,so as to provide a theoretical basis for actual production. |
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