Performance of Bos indicus steers in rearing and their holistic effects on finishing: a nutrigenomics perspective

Abstract

The performance of beef cattle during the backgrounding phase plays a pivotal role in enhancing the overall efficiency, sustainability and productivity of the beef production chain. Typically, backgrounding is the longest phase in the lifespan of animals designated for meat production, thereby becoming a key period for intensification and the enhancement of production efficiency. Several studies have elucidated the phenotypic effects of performance variation during backgrounding on other characteristics of beef cattle in the finishing phase. However, both the phenotypic and molecular effects of such performance remain incompletely understood, particularly in tropical production systems. In this context, the objective of this research is to assess how performance during the backgrounding phase may influence, both phenotypically and at the molecular level, the finishing of beef cattle, through a nutrigenomics approach. To achieve this, we will use 64 Nellore steers, with an average weight of 261.5±14.1 kg and 7.1±0.4 months of age, randomly distributed in a completely randomized design. The animals will be subjected to four distinct treatments based on their total weight gain during the 12-month backgrounding period, namely: T1 - Low (3@, 90 kg), T2 - Marginal (5@, 150 kg), T3 - Average (7@, 210 kg), and T4 - High (9@, 270 kg). At the end of this period, the animals will be placed in a feedlot for a 100-day finishing phase. The animals will be evaluated for their average daily gain, feed intake and efficiency, reproduction, and after slaughter, carcass characteristics and meat quality will be analyzed. The nutrigenomic study will be conducted through the collection of biological samples for serum, hepatic and muscular metabolomics and ruminal fluid microbiome analyses. Phenotypic data will be subjected to analysis of variance utilizing linear models, while metabolomic analyses will be conducted through multiple linear regressions, and the microbiome will be assessed by analyzing taxonomic differential abundance. This comprehensive study aims to elucidate the molecular, microbiome and phenotypic effects of backgrounding performance on the finishing phase. (AU)