Effects of Small Peptide Supplementation in Diets with Fermented Mixed Meals on Rumen Fermentation Parameters and Microflora of Beef Cattle
This experiment aimed to investigate the effects of small peptide supplementation in diets with fer-mented mixed meals on rumen fermentation parameters and microflora of beef cattle.Twenty-eight healthy Sim-mental crossbred cattle with(481.43±36.36)kg of initial weight were randomly divided into 4 groups with 7 replicates per group and 1 cattle in each replicate.Cattle in the 4 groups were fed fermented mixed meal total mixed rations with small peptide supplemental levels of 0(group Ⅰ,as control group),0.5％(group Ⅱ),1.0％(group Ⅲ)and 1.5％(group Ⅳ),respectively.The pre-test period lasted for 25 days and the trial las-ted for 60 days.The results showed as follows:1)with the increase of small peptide supplemental level,the proportion of butyrate showed a quadratic curve change(P=0.037),the proportion of iso valerate tended to decrease linearly(P=0.080),and the proportion of propionate had a tendency of quadratic curve change(P=0.082).2)Ace index and Chao index had a quadratic curve change with the increase of small peptide supple-mental level(P=0.030,0.036,respectively).3)At phylum level,the dominant phyla were Bacteroidetes,Firmicutes,and Proteobacteria,and with the increase of small peptide supplemental level,the relative abun-dances of Firmicutes,Tenericutes and Saccharibacteria presented a tendency of quadratic curve change(P=0.097,0.074,0.077,respectively).At genus level,the relativeabundance of Prevotella_1 was the dominant genus,and with the increase of small peptide supplemental level,the relative abundance of Prevotella_1 had a tendency of quadratic curve change(P=0.089);the relative abundance of Rikenellaceae_RC9_gut_group showed a quadratic curve change with the increase of small peptide supplemental level(P=0.042),and its was negatively correlated with the proportions of propionate(r=-0.489,P=0.029)and valerate(r=-0.529,P=0.016);the relative abundance of Christensenellaceae_R7_group of group Ⅱ was significantly higher than that of other groups(P＜0.05),it was positively correlated with the proportions of acetate(r=0.678,P=0.001),butyrate(r=0.481,P=0.032)and acetate/propionate(r=0.729,P＜0.001),and was negatively correlated with the proportion of propionate(r=-0.729,P＜0.001).In conclusion,on the conditions of the present study,supplementing small peptides to diets with fermented mixed meals can affect the rumen microbial richness and diversity,alter the microbial composition at phylum and genus levels,and optimize the composi-tion and proportions of volatile fatty acids in the rumen of beef cattle.[Chinese Journal of Animal Nutrition,2024,36(8):5094-5106]
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