Rumen metagenomics of Nellore beef cattle submitted to intensified grazing systems during different seasons

Abstract

This project is enrolled to a Thematic Project (2017/20084-5) from the Research Call - FAPESP Program for Research in Global Climatic Changes (PFPMCG)- "Climatic Changes: Adaptation and Mitigation, which involves four important projects conducted in São Carlos (Embrapa), Nova Odessa (IZ-Instituto de Zootecnia) and Pirassununga (USP). The present project research (2019/19396-8), "Metabolism and rumen metagenomic of beef cattle under intensified grazing systems during different seasons", has been conducted in Pirassununga - SP, and it is proposed to conduct part of the Metagenomic trial in Department of Bacteriology at University of Wisconsin. It is well known that beef cattle have influence over the greenhouse gases released to the atmosphere, mainly the methane gas, especially when the production system is poorly technified. On this project, it is proposed to investigate the microbiota of Nellore beef cattle in the intensified grazing systems during different seasons. To do that, sampled rumen solid and liquid material were collected in two years-trial from eight cannulated Nellore cattle distributed in eight experimental units of four treatments, they are already preserved and will be transported and analysed at the Department of Bacteriology of the University of Wisconsin-Madison. The experimental treatments were composed by combination of two different grazing systems with supplementation of ammonium nitrate (NH4NO3) or urea, they are as follows: 1) Rotational grazing system with urea supplementation (RG+US); 2) Rotational grazing system with NH4NO3 supplementation (RG+AS); 3) Deferred grazing system with urea supplementation (DG+US); 4) Deferred grazing system with NH4NO3 supplementation (DG+AS). It is planned to perform DNA extraction, library build and sequencing, taxonomical profile, community structure and diversity of each sample. A metagenomic approach can be useful to target the microbial community (by means amplicon sequencing) and provide to us a deep insight of the isolated and combined effect of nitrate, grazing and seasons (dry, mid-dry, rainy, and mid-rainy) on Nellore beef cattle's ruminal metabolism. Sequences reads' data from each sample will be analyzed using the Mothur software v.1.35.0 to better understand the treatment effect on community richness and diversity.