Effect of fermented total mixed rations on rumen microbial communities and serum metabolites in lambs

Background:Diet regulates rumen microbiota,which in turn affects animal health.The present study evaluated the response of rumen microbiota and the immune system of lambs to a fermented total mixed ration diet.Methods:A total of 30 lambs were assigned into two groups:a group fed an unfermented high-fiber diet(total mixed ration[TMR])and a group fed an fermented low-fiber diet(fermented TMR[FTMR]).Results:The results showed that FTMR markedly(p<0.05)increased average daily gain and dry matter intake compared to TMR.The FTMR diet increased the relative abundance of Veillonellaceae_UCG-001 and decreased the diversity of undesirable microbiota despite stable overall microbial community diversity.Serum metabolomic analysis combined with enrichment analysis showed that serum metabolites were affected by the FTMR and metabolic pathways,and the FTMR diet significantly(p<0.05)influenced amino acid metabolism of lambs.There was a decrease in inflammatory factors in the FTMR treatment,indicating that inflammatory factors followed the same trajectory as changes in microbial community structure and function.Conclusions:Overall,the FTMR diet reduced undesirable microbiota diversity,thereby regulating host amino acid metabolism and improving immune status.

中国北方草地植物补偿性生长与合理放牧强度:基于放牧实验的整合分析

补偿性生长是草地植物对动物采食的一种适应策略,合理的放牧强度能够促进植物的补偿性生长,有利于草地生产力和稳定性的维持,而长期过度放牧则导致草地退化.因此,确定合理的放牧强度是科学配置草地生产-生态功能实现草牧业可持续发展的基础.本文基于各类放牧实验已发表的118篇研究文献,将放牧家畜的采食率(地上生物量移除量,%)作为放牧强度的测度指标,对我国北方5种主要草地类型的植物补偿生长特征及其合理放牧强度进行了整合分析,并结合气候、土壤及植物群落地下生物量和多样性等数据,厘清了影响植物补偿生长的关键生物和非生物因子.结果表明,我国北方草地植物总体处于欠补偿生长状态,且植物地上部分的补偿性生长主要以牺牲其地下生物量为代价.其中,高寒草甸、草甸草原和荒漠草原植物群落均表现为欠补偿生长,高寒草原和典型草原植物群落表现为等补偿生长.在区域尺度上,补偿性生长的绝对值随年降水量和植物物种丰富度的增加而增加.满足植物群落地上生物量实现等补偿或超补偿,且对地下生物量不产生负效应,各类草地的合理利用强度为:高寒草甸50%、草甸草原48%、典型草原40%、高寒草原37%、荒漠草原31%.本研究对指导我国北方草地保护与合理利用,以及退化草地恢复具有重要的理论和实践意义.