Application of omics on the impact of feeding with guanidinoacetic acid on the growth and finishing stages of Nelore bulls

• Grant number: 23/13173-2
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2024
• End date: December 31, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Paulo Roberto Leme
• Grantee: Letícia Carolina Bortolanza Soares
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated scholarship(s): 25/06537-3 - Effect of rumen-protected methionine supplementation on antioxidant status and DNA methylation in bovine spermatozoa, BE.EP.DR

Abstract

The rearing phase is a period of greater animal growth, however, it is the longest phase within the beef cattle production cycle. This is due to the fact that this rearing phase is carried out in pasture systems, in which the seasonality in the supply and quality of forage interferes with the animal's growth. On the other hand, as the animal approaches maturity, there is a deceleration in the growth rate and changes in the gain composition, requiring more energy to meet performance demands. Several feeding strategies in rearing, mainly with supplements based on protein and energy, and in different offers are currently used in order to improve growth, reduce the production cycle and bring animals earlier for slaughter, aiming to improve quality of the flesh. Food additives such as guanidinoacetic acid are used in medicine for treatments to prevent muscle atrophy and as hypertrophy stimulants in individuals who perform physical activity. Also, this compound has been used in poultry and swine production, and recently in cattle, only in confinement finishing to improve performance. This proposal aims to evaluate the biological and metabolic mechanisms and the animal response to guanidinoacetic acid nutrition during the growth and finishing phases in Nellore young bulls using a systems biology approach. Forty-eight newly weaned Nelore calves weighing approximately 210 kg and eight months old will be housed in 12 paddocks with Brachiaria spp. Before starting the experimental period, the calves will be weighed, blocked and randomly distributed in four treatments. A single protein-energy supplement (29% CP) will be used in the rearing phase and a single finishing diet. In the pasture supplement and in the finishing diet, three doses of guanidinoacetic acid (GAA) will be included, 3, 6 and 9 g/kg DM in the supplement and 0.3; 0.6 and 0.9 g/kg DM in finishing, respectively, GAA3, GAA6 and GAA9, compared to a supplement and diet without acid inclusion (CON). During the rearing, the animals will be weighed every 28 days and at the end, the weights will be recorded at the beginning, middle and end of confinement. At the end of the rearing phase, and during slaughter, samples of liver, plasma and Longissimus thoracis muscle on the right side will be collected for gene expression, proteomics and metabolomics analyses. At slaughter, meat samples will be collected for analysis of chemical composition, color, shear force, cooking losses and sarcomere length. The expected results in this research will be earlier animals for slaughter, improving the qualitative characteristics of the meat, as well as a faster return on investment associated with a short production cycle