Optimizing nutrient utilization in beef cattle: the effects of narasin and rumen-protected methionine supplementation

• Grant number: 22/16529-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2023
• End date: June 30, 2025
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Ana Laura Januário Lelis
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The use of feed additives in beef cattle production is crucial for improving performance, health, and feed efficiency. Additives like narasin, an ionophore, enhance feed efficiency, control coccidiosis, and improve energy utilization, leading to better weight gain and feed conversion. Additionally, rumen-protected amino acids, such as methionine, support protein synthesis and improve muscle development and carcass quality. These strategies help producers achieve more sustainable, economically viable operations and meet the demand for high-quality beef products. In this context, this project includes two studies. Study I aim to evaluate the effects of adding Narasin at different doses on ruminal selection patterns, bacterial community composition and nutrient digestibility in confined Angus cattle. Three castrated Angus steers with an approximate live weight of 680 kg and age of 36 months, rumen cannulated, will be used. The research used a 3x3 duplicated Latin square design, involving three Angus steers cannulated in the rumen with an approximate live weight of 680 kg. The treatments include 13, 20 and 27 ppm of narasin, integrated into a finishing diet with 87% concentrate. The hypothesis is that increasing narasin levels will affect ruminal metabolism, leading to planned changes in production patterns and microbial communities. This study will contribute important insights into the optimal use of narasin in feedlot systems, significantly increasing feed efficiency and improving overall cattle performance. Study II aims to evaluate the impact of adding rumen-protected methionine (RPM) to standard supplementation protocols on growth performance, carcass characteristics, and rumen morphometry of crossbred heifers finished on pasture in Brazil. Forty-eight 18-month-old crossbred heifers (½ Nellore x ½ Angus) with an approximate live weight of 380 kg will be used. The heifers will be randomly allocated to 12 paddocks and subjected to different supplementation protocols, with varying levels of RPM. The hypothesis is that the inclusion of RPM will increase growth performance and meat quality and allow the reduction of supplementation in the early stages of the trial without negatively impacting the studied variables. This research will provide insights into the optimization of supplementation strategies for pasture-finished beef cattle, potentially improving overall animal performance and meat quality in Brazilian pasture systems.