Fecal bacteriome of Nellore steers with high and low feed efficiency phenotypes

• Ano de defesa: 2020
• Autor(a) principal: Rossi, Letícia Elisa
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Nelore(Bovino); Eficiência da conversão de alimentos; Microorganismos intestinais; Ciências Agrárias I
• Link de acesso: https://locus.ufv.br//handle/123456789/27940

To improve the production performance of beef and dairy cattle herds and reduce the environmental impact related to methane emissions, there is a growing interest of producers and researchers in the study of the factors that influence the phenotype of feed efficiency in cattle and develop methods that to identify more feed-efficient animals in commercial herds. Previous studies suggest that cattle of high and low feed efficiency have differences in the composition of the rumen microbiome, however, the association of these phenotypes with fecal microbiota of ruminants, particularly Nellore cattle, has not yet been established. Thus, in this work, the objective was to evaluate whether the fecal microbiota of Nellore cattle could be used as an indicator of feed efficiency for beef cattle. Fifty-nine Nellore steers, comprising 29 animals showing negative (high feed-efficiency, n-RFI) and 30 showing positive (low feed-efficiency, p-RFI) residual feed intake (RFI), were selected for this study. Fecal samples were collected, genomic DNA was extracted and the V4 region of the 16S rRNA gene was amplified and paired-end reads were generated via Illumina MiSeq sequencing. Metataxonomic analyses indicated significant differences in species richness (Chao-1) and diversity (Shannon) between the fecal microbiota of n-RFI and p-RFI steers (Mann-Whitney test, P<0.05). Firmicutes and Bacteroidetes were the most abundant phyla in the fecal-associated microbiota of Nellore steers and members of the genera Ruminococcaceae_UCG- 014, dgA-11_gut_group, Treponema_2 e Slackia showed significant differences in fecal samples from the n-RFI and p-RFI groups. Otu00008 (Roseburia spp.) showed the highest abundance among OTUs with significant differences between the two efficiency groups, being more abundant in the n-RFI group. The results suggest that these bacterial groups can be used as potential biomarkers of the feed efficiency phenotype in Nellore cattle. However, further studies will be necessary to validate the results obtained, including functional analysis of fecal microorganisms and using larger cohorts of animals on a commercial scale. Keywords: Nellore cattle. Feed efficiency. RFI. Fecal microbiota. 16S rRNA gene.