饲养水平对阿勒泰羊胃肠道发育、瘤胃发酵参数及瘤胃微生物区系的影响

为研究饲养水平对阿勒泰羊胃肠道发育、瘤胃发酵参数、消化酶活性及瘤胃微生物区系的影响,选取月龄相近(3～3.5月龄)、体重均一(19.16±0.54)kg、臀型一致、健康状况良好的阿勒泰母羔羊30只,随机分为3组,每组10只,自由采食60 d后,参照NRC(2007)饲养标准中维持能量(Em)需要,3个组分别按1.5Em...

Effects of feeding level on the gastrointestinal development,rumen fermentation and rumen microbiota in Altay sheep

The purpose of this experiment was to study the effects of relative feeding level on rate of bodyweight gain,carcass dressing out performance,meat quality and organ development in Altay sheep.Thirty 3.0 to 3.5 month old Altay female lambs with a similar body weight of(19.16±10.54)kg and uniform tail size were randomly divided into 3 groups with 10 lambs per group.After 60 days of adlibitum feeding,three differential feeding levels were imposed for a further 30 days.The differential feeding levels were calculated based on feeding standards published by the National Research Council,USA,in 2007,defining maintenance energy(Em)requirements and lambs in each group were fed diets supplying 1.5×(1.5 Em),1.0×(1.0 Em)or 0.5×(0.5 Em)the calculated Em(0.75,0.50 and 0.25 MJ metabolizable energy per kg0.75 body weight,respectively).It was found that:1)The weights of the whole stomach,rumen,and small intestine and a rumen size index decreased with decrease in feeding level,and the weights of the whole stomach,rumen and small intestine fed at 1.5 Em were significantly higher(P<0.05)than in groups fed 1.0 Em and 0.5 Em,while the length of small intestine and a small intestine size index in groups fed 1.5 Em and 1.0 Em were significantly increased(P<0.05)compared with the group fed 0.5 Em.And there was no significant difference between the 1.5 Em and the 1.0 Em groups(P>0.05).2)The pH of rumen fluid was highest in the 1.0 Em group and rumen pH for the group fed 1.5 Em was significantly lower(P<0.05)than both the 1.0 Em and 0.5 Em groups.NH3-N content decreased gradually with decrease feeding level,but the differences between the three groups was not statistically significant(P>0.05).Total volatile fatty acids(TVFA),acetic acid,propionic acid,butyric acid,valeric acid,isobutyric acid and isovaleric acid concentrations in rumen fluid of lambs fed 1.0 Em were the lowest,and rumen TVFA,acetic acid and propionic acid levels of lambs fed 1.0 Em were significantly lower(P<0.05)than in lambs fed 1.5 Em and 0.5 Em.The length of the small intestine and the small intestine size index of lambs fed 1.5 Em and 1.0 Em were increased significantly(P<0.05)compared to lambs fed0.5 Em.Rumen butyric acid and valproic acid concentrations and acetic∶propionic acid in groups fed 1.0 Em and0.5 Em groups were significantly lower(P<0.05)than in the group fed 1.5 Em.3)The activities of digestive enzymes in rumen fluid decreased with the decrease of feeding level;the activities of lipase and protease in the group fed 1.5 Em were significantly higher(P<0.05)than in the groups fed 1.0 Em and 0.5 Em,and there was no significant difference(P>0.05)between the groups fed 1.0 Em and 0.5 Em.Alpha-amylase activity differed significantly(P<0.05)among three groups.4)The relative abundance of fungi and protozoa in rumen fluid of lambs fed 1.5 Em was significantly higher(P<0.05)than in lambs fed 1.0 Em and 0.5 Em,and the differences between 1.0 Em and 0.5 Em groups were not significant(P>0.05).Counts of Fibrobacter succinogenes and Ruminococcus albus were the lowest in lambs fed 1.0 Em,and were significantly lower(P<0.05)than counts in the1.5 Em and 0.5 Em groups.Ruminococcus flavefaciens counts did not differ significantly among the three groups(P>0.05).These results show that feeding level has a significant effect on the gastrointestinal development,rumen fermentation parameters,activities of digestive enzymes and rumen microbiota in Altay sheep.