Different combinations of protein and energy feeds with condensed tannins for beef cattle backgrounded on pasture and finished in feedlot.

• Grant number: 25/08197-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: September 01, 2025
• End date: December 31, 2028
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Ricardo Andrade Reis
• Grantee: Richard Vaquero Ribeiro
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil
• Associated research grant: 22/15974-0 - Strategic grazing management and supplementation towards sustainable intensification at tropical pasture-based beef cattle production systems, AP.TEM

Abstract

This project aims to evaluate the effects of different combinations of protein and energy feedstuffs not suitable for human consumption and condensed tannins (CT) during the backgrounding phase on fertilized pastures and the finishing phase in feedlot systems, focusing on metabolism, ruminal microbial diversity, performance, and enteric methane emissions. The hypotheses of these studies will be tested through two trials: Study 1 will be conducted in feedlot, where the effects of different protein sources (peanut meal (PM) and dried distillers grains with solubles (DDGs)) combined with tannins will be evaluated for the above-mentioned parameters. A total of 104 Nelore bulls will be used, with 96 animals allocated for performance evaluation and 8 animals for metabolism assessment. For performance evaluation, animals will be blocked by initial body weight (light, heavy) and randomly assigned within each block in a 2 × 2 factorial design (Factor A: protein source; Factor B: with and without tannin additive), resulting in four treatments: T1 - DDGs; T2 - DDGs + CT; T3 - PM; T4 - PM + CT. The performance evaluation will last 105 days, including 15 days of adaptation and 90 days of finishing (3 periods of 30 days). At the end of the performance period, 48 animals will be used to assess enteric methane emissions over 15 days, with 9 days of adaptation and 6 consecutive days of collection. The metabolism trials will occur simultaneously with the performance evaluation, using eight rumen-fistulated animals in a balanced 4 × 4 double Latin square design, in which the four experimental diets will be evaluated over four 21-day periods. During these periods, feces, urine, and rumen content will be collected to evaluate digestibility, nitrogen balance and utilization efficiency, ruminal fermentation parameters (pH, NH¿-N, and short-chain fatty acids), and microbial diversity. In Study 2, the effects of different tannin-rich energy sources (ground sorghum (SG) and peanut skin (PS)) combined with supplemental tannins on the parameters described above will be evaluated. The backgrounding phase will be conducted on pasture using 48 tester animals for performance evaluation and 8 rumen-fistulated animals for metabolism. Performance will be assessed using a completely randomized design in a 2 × 2 factorial arrangement (Factor A: energy source; Factor B: with and without tannin additive), resulting in four treatments and three replications (paddocks). The experimental treatments will be randomly assigned to the experimental units: T1 - PS; T2 - PS + CT; T3 - SG; T4 - SG + CT. These treatments will consist of energy supplements provided at 0.3% of the animals' body weight. The performance period will last 84 days, divided into three 28-day periods. Additionally, enteric methane emissions will be evaluated during a fourth 28-day period. The metabolism trial will be conducted concurrently with the performance evaluation, using eight rumen-fistulated animals assigned to a balanced 4 × 4 double Latin square design within the experimental paddocks. The four experimental diets will be evaluated over four 21-day periods, and the same evaluations as in Study 1 will be performed. The results obtained in this project will support decision-making on whether to combine tannins with different protein and energy sources to improve productive efficiency in feedlot and pasture systems while reducing environmental pollution. (AU)