| In order to explore the effects of diets with different nitrogen-sulfur ratios on rumen tissue morphology,fermentation parameters,and microbial community structure and function of Tibetan lambs under the same conditions of energy and protein levels.Therefore,the optimal ratio of nitrogen and sulfur for weaning Tibetan lambs was selected.In this study,150 60 day old weaned Tibetan lambs with similar initial conditions were randomly divided into 5 groups with 30 lambs in each group.They were fed with diets with the same energy and protein nitrogen sulfur ratios of 10.5:1（A）,9:1（B）,7.5:1（C）,6:1（D）and 4.5:1（E）to 180 day old.After the experiment,rumen tissues were collected to make frozen sections to measure the length,width,density,mucosal thickness,submucosal thickness,and muscle thickness of the rumen papilla;rumen fluid was collected to measure rumen fermentation parameters（rumen fluid p H,ammonia nitrogen,Volatile fatty acids,bacterial proteins）;and use high-throughput sequencing technology to determine the structure and function of rumen microbes.The results are as follows:（1）The length of rumen nipple,thickness of submucosa and thickness of muscle layer in group B were significantly higher than those in the other four groups（P<0.05）;the length of rumen nipple in groups C,D and E were significantly higher than those in group A;the width of rumen nipple in groups B,C and D were significantly higher than those in groups A and E（P<0.05）;the density of rumen nipple in groups B and E were significantly higher than those in the other three groups（P<0.05）;the thickness of keratotic layer in group C was significantly higher than that in other groups（P<0.05）,There was no significant difference between the other groups（P>0.05）.（2）There was no significant difference in p H among groups（P>0.05）;the content of NH3-N in group B was significantly lower than that in other groups（P<0.05）;the bacterial protein in group A,B and D was significantly higher than that in group C and D（P<0.05）;the content of total volatile acid（TVFA）,acetic acid,propionic acid,butyric acid,isobutyric acid,isovaleric acid and valeric acid in rumen fluid in group B was significantly higher than that in other groups（P<0.05）.（3）Comparing the Alpha diversity index of the five groups,the Shannon index of group B was significantly higher than that of group A（P<0.05）;the Simpson index of group A was significantly higher than that of group B,C,D and E（P<0.05）;the Chao1index and Ace index of group B were significantly higher than those of other groups（P<0.05）;the gene library coverage rate was more than 99.9%.Among the top ten phyla with relative abundance more than 0.1%at phylum level,Firmicutes was the dominant phyla in five groups.At the family level,the dominant families in the five groups were Lachnospiraceae,Christensenellaceae,Veillonella and Ruminococcaceae.Lachnospiraceae in group D was significantly higher than that in groups A,B and E（P<0.05）,and Veronicaceae in group A was significantly higher than that in group C（P<0.05）.The dominant bacterial genera in the five groups at the genus level are Christensenellaceae＿R-7＿group,Quinella,Ruminococcaceae＿NK4A214＿group and Lachnospiraceae＿XPB1014＿group;among them,Quinella in group A is significantly higher than that in groups C and D（P<0.05）and there is no significant difference between group A and group B（P>0.05）;Lachnospiraceae＿XPB1014＿group of C,D,E group was significantly higher than that of group A（P<0.05）,and it was not significantly different from group B（P>0.05）.The PICRUSt function prediction results show that the functions of the rumen flora mainly focus on the transport and metabolism of carbohydrates and amino acids.Therefore,considering the above results and economic benefits,when the nitrogen-sulfur mass ratio is 9:1,it is more in line with the efficient breeding of Tibetan lambs.The results provide theoretical basis and data support for the establishment of a high-efficiency breeding technology system for Tibetan lambs in Qinghai Province. |
PDF Full Text Request