低蛋白日粮补充亮氨酸和色氨酸对哺乳犊牛直肠微生物的影响

Effects of Leucine and Tryptophan Supplementation in Low Protein Diet on Rectal Microorganisms in Lactating Calves

试验旨在研究低蛋白日粮补充亮氨酸(Leu)和色氨酸(Trp)对哺乳犊牛直肠微生物的影响,选取初生体重[(40±2)kg]相近、健康状况良好的中国荷斯坦犊牛75头,采用完全随机试验设计,随机分为5组,分别为HK组[22%粗蛋白(CP)水平开食料]、LK组(19%CP水平开食料)、L组(19%CP水平的开食料+1.15%Leu)、T组(19%CP水平开食料+0.26%Trp)、LT组(19%CP水平开食料+1.15%Leu+0.26%Trp),犊牛10日龄开始自由采食不同成分的开食料,试验期为49 d。结果表明:犊牛59日龄时,L组、T组和LT组Chao1和Observed species指数低于HK组,T组Chao1和Observed species指数均高于LK组。在门水平上,优势菌门为厚壁菌门和拟杆菌门,占比为90.03%。犊牛粪便微生物在门水平上的相对丰度均差异不显著(P>0.05);在属水平上,L组、T组和LT组粪杆菌属相对丰度高于LK组,且L组显著高于LK组(P<0.05);L组、T组和LT组普雷沃氏菌属相对丰度高于LK组(P>0.05)。综上,低蛋白日粮补充Leu和Trp对哺乳犊牛直肠微生物门、属水平除粪杆菌属外均无显著性影响,说明低蛋白日粮补充Leu和Trp对哺乳犊牛直肠微生物影响较小。

The purpose of the experiment was to study the effects of low protein diet supplemented with leucine(Leu)and tryptophan(Trp)on rectal microorganisms of lactating calves.A total of 75 Chinese Holstein calves with similar birth weight[(40±2)kg]and good health were randomly divided into five groups.They were HK group[22%crude protein(CP)level diet],LK group(19%CP level diet),L group(19%CP level diet+1.15%Leu),T group(19%CP level diet+0.26%Trp)and LT group(19%CP level diet+1.15%Leu+0.26%Trp).Calves began to eat different ingredients freely at the age of 10 days,and the trial period was 49 days.The results showed that at 59 days of age,the Chao1 and Observed species index of L group,T group and LT group were lower than those of HK group,while Chao1 and Observed species index of T group were higher than those of LK group.At the phylum level,the dominant phyla were Firmicutes and Bacteroidota,accounting for 90.03%.There was no significant difference in relative abundance of microorganisms in calf feces at door level(P>0.05).At the genus level,the relative abundance of Faecalibacterium in group L,group T and LT was higher than that in group LK,and that in group L was significantly higher than that in group LK(P<0.05),and the relative abundance of Prevotella in group L,group T and LT was higher than that in group LK(P>0.05).In summary,the supplementation of Leu and Trp in low protein diet has no significant effect on phylum level,but it has an effect on Faecalibacterium in the genus level,indicating that the supplementation of leucine and tryptophan in low protein diet has little effect on rectal microorganisms of lactating calves.