日粮蛋白水平对育肥藏羊瘤胃细菌多样性的影响

Effect of dietary protein level on rumen microbial diversity of fattening Tibetan Sheep

为了研究不同蛋白水平对育肥藏羊瘤胃细菌多样性的影响,选取健康且体况相近的3月龄早期断奶藏羊公羔15只,平均体重为(22.05±2.06)kg,随机分为3组,日粮粗蛋白水平分别为10.08%(Ⅰ组),12.84%(Ⅱ组)和14.97%(Ⅲ组)。预试期7 d,正试期112 d。饲养实验结束后对试验羊进行屠宰并于不同位点采集瘤胃液样品,测定瘤胃细菌的相对丰度。结果表明:(1)Shannon指数和Simpson指数各组之间无显著性差异(P>0.05),ACE指数和Chao l指数Ⅰ组显著高于Ⅱ组和Ⅲ组(P<0.05)。(2)门水平下,拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)为瘤胃细菌的优势菌门,且均随日粮蛋白水平提高而显著增加(P<0.05);变形菌门(Proteobacteria)和放线菌门(Actinobacteria)相对丰度Ⅱ组显著较高(P>0.05)。(3)科水平下,毛螺菌科(Lachnospiraceae)相对丰度较高,但各组之间差异不显著(P>0.05);瘤胃球菌科(Ruminococcaceae)相对丰度Ⅱ组和Ⅲ组显著高于Ⅰ组(P<0.05);韦荣氏菌科(Veillonellaceae)相对丰度Ⅲ组显著高于Ⅰ组(P<0.05)。(4)属水平下,Prevotella(普雷沃氏菌属)的相对丰度Ⅲ组显著高于Ⅰ组和Ⅱ组(P<0.05),瘤胃球菌属(Ruminococcus)Ⅱ组相对丰度显著较高(P<0.05)。(5)PCA分析显示各组间瘤胃细菌结构差异不明显,但采食低蛋白水平日粮的藏羊瘤胃细菌相似度更高,能更好聚类在一起。综上可知,不同蛋白水平对育肥藏羊瘤胃细菌多样性无显著影响,但可影响其丰富度;同时随着日粮蛋白水平的提高,厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)相对丰度显著增加,普雷沃氏菌属(Prevotella)在日粮蛋白水平为14.97%时更适宜生长,瘤胃球菌属(Ruminococcus)则在日粮蛋白水平为12.84%时活性更高。

In order to study the effects of different protein levels on rumen bacterial diversity of fattening Tibetan sheep, fifteen healthy 3-month-old Tibetan lambs with an average weight of(22.05±2.06) kg were randomly divided into three groups. The lambs in the treatment groups were fed diets with crude protein levels at 10.08%(group Ⅰ), 12.84%(group Ⅱ) and 14.97%(group Ⅲ), respectively. The pre-experimental period lasted for 7 days, and the experimental period lasted for 112 days. At the end of the experiment, all individuals were slaughtered and then the rumen fluid samples were collected from different sites for determining the relative abundance of rumen bacteria.The results showed that:(1) There was no significant difference in Shannon index and Simpson index among groups(P > 0.05). Ace index and Chao 1 index in group Ⅰ were significantly higher than those in group Ⅱ and group Ⅲ(P <0.05).(2) At the phylum level, the relative abundance of Proteobacteria and Actinobacteria in group Ⅱ was significantly higher than that in group Ⅱ(P > 0.05).(3) At the family level, the relative abundance of Lachnospiraceae was higher, but there was no significant difference among groups(P > 0.05). The relative abundance of Ruminococcaceae in group Ⅱ and group Ⅲ was significantly higher than that in group Ⅰ(P < 0.05). The relative abundance of Veillonellaceae in group Ⅲ was significantly higher than that in group Ⅰ(P < 0.05).(4) At genus level, the relative abundance of Prevotella in group Ⅲ was significantly higher than that in groups I and II(P < 0.05), and which of Ruminococcus in group Ⅱ was significantly higher(P < 0.05).(5) PCA analysis showed that there was no significant difference in rumen bacterial community structure among the groups, but there was a trend of separation between the groups. The bacteria of Tibetan sheep fed with low protein diet had higher similarity and better clustering. In conclusion, different protein levels had no significant effect on rumen bacterial diversity of fattening Tibetan sheep, but which could affect its richness;meanwhile, with the increase of dietary protein level, the relative abundance of Firmicutes and Bacteroidetes increased significantly, Prevotella was more suitable for the growth when the dietary protein level was 14.97%, while Ruminococcus was more active when the dietary protein level was 12.84%.