不同蛋白水平饲粮对犊牛瘤胃微生物区系多样性及组成的影响

Effects of Diets with Different Protein Level on Rumen Bacterial Community in Calves

通过饲喂不同蛋白水平开食料,研究其对断奶前后犊牛瘤胃发酵参数和瘤胃微生物多样性的影响。选取30头20日龄健康荷斯坦公犊牛,随机分为2组,每组15头。饲喂粗蛋白水平分别为19%(L)和22%(H)的两种开食料。预试期10 d,正试期60 d。每天测定采食量,每隔30 d测量体重;在60和90日龄时饲喂前颈静脉采血,测定尿素氮;每组随机选取4头分别在30、60和90日龄晨饲后2 h口腔采集瘤胃液,测定NH 3-N、VFA和瘤胃微生物多样性。结果表明:(1)试验全期,两组间的平均日增重(ADG)和日均采食量(ADFI)均差异不显著(P>0.05);90日龄时,H组的尿素氮(BUN)显著高于L组(P<0.05)。(2)饲粮蛋白水平对瘤胃pH、NH 3-N、丙酸比例、丁酸比例和乙酸/丙酸比无显著影响,90日龄时,H组的乙酸比例显著低于L组(P<0.05)。(3)Chao指数和PD_whole_tree指数分别比H组显著提高20.7%、17.4%(P<0.05),其余多样性指数无显著差异(P>0.05)。(4)门水平上,L、H两组的优势菌群均为厚壁菌门、拟杆菌门、放线菌门和变形菌门,但两组间优势菌群含量差异不显著(P>0.05)。属水平上,优势菌属为罗斯氏菌属、普雷沃氏菌属和欧陆森氏菌属,但两组间优势菌群含量差异不显著(P>0.05)。综上所述,饲粮蛋白水平对瘤胃发酵类型及瘤胃菌群在门水平和属水平上均不显著。

The purpose of this study was to evaluate the effects of diets with different protein level on rumen fermentation and rumen bacterial community of calves before and after weaning.Thirty Holstein calves aged 20 days were randomly divided into two treatment groups with fifteen calves in each group.Each group was fed 19%(L)and 22%(H)crude protein diet,respectively.The test period was 70 d,of which adaptation period was 10 d and formal period was 60 d.Feed intake was recorded everyday,and body weight was measured every 30 d.At the age of 60 and 90 days,blood was sampled from the anterior jugular vein and urea nitrogen was measured.Rumen fluid was collected in the oral cavity 2 h after feeding at the age of 30,60 and 90 days,respectively,to measure NH 3-N,VFA,rumen bacterial community.The results showed that:(1)there were no significant differences in average daily gain(ADG)and average daily feed intake(ADFI)between the two treatment groups during the whole period of the experiment(P>0.05).The urea nitrogen(BUN)in the 90-day-old H group was significantly higher than those in the L group(P<0.05).(2)As crude protein level increased,there was no significant difference in rumen pH,ammonia nitrogen,Propionate,Butyrate and Acetate-propionate ratio between the two treatment groups.Acetate in the 90-day-old H group was significantly lower than those in the L group(P<0.05).(3)The Chao index and PD_whole_tree index was significantly increased by 20.7%and 17.4%(P<0.05)compared with group H.There was no significant difference in other indexes between the two groups(P>0.05).(4)At the phylum level,the dominant bacteria in L and H groups were Firmicutes,Bacteroidetes,Actinobacteria and Proteobacteria,but there was no significant difference in the content of dominant bacteria between the two groups(P>0.05).At the genus level,the dominant bacteria were Roseburia,Prevost and Olsenella,but there was no significant difference in the content of dominant bacteria between the two groups(P>0.05).To sum up,as crude protein level increased,rumen fermentation type had not changed,and there is no significant difference in rumen bacterial community at both the phylum level and the genus level by feeding different protein levels of diets.