EVALUTION OF ENERGY SUPPLEMENTAION ASSOCIATED WITH CONDENSED TANNIN IN OF GROWING NELLORE BULLS ON PASTURE

• Grant number: 25/09930-8
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2025
• End date: February 28, 2027
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Ricardo Andrade Reis
• Grantee: Willi Rocha Meireles
• 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

Brazil is identified as the largest emitter of enteric methane (CH¿) when compared to other global beef producers. The enteric origin of CH¿ is directly related to the efficiency of ruminal fermentation due to carbon loss and, consequently, energy loss, which reduces animal performance in addition to its environmental impact. However, the use of concentrates in the diets of cattle on pasture may be a viable strategy for mitigating CH¿ emissions. Citrus pulp has been used as a nutrient source for the sustainable intensification of livestock production, increasing the soluble nitrogen use from forage plants. Similarly to citrus pulp supplementation, condensed tannins also influence ruminal N recycling by forming tannin-protein complexes. Therefore, the objective of this study is to evaluate the effect of energy supplementation with citrus pulp, associated or no with tannin, on metabolism, performance, and mitigation of enteric CH¿ emissions in growing Nellore bulls on Urochloa brizantha (Hochst. ex A. Rich) Stapf cv. Marandu pastures. Two concurrent experiments will be conducted at the Forage Crops Sector of FCAV/UNESP. In the first experiment, a metabolism trial will be conducted concomitate a performance trial, using 8 rumen-cannulated Nellore steers (average body weight 230 ± 40 kg), arranged in two 4 × 4 Latin squares in a factorial arrangement (2x2: Factor A - salt and pulp; Factor B - with tannin, without tannin). The experiment will last 84 days, with four experimental periods of 21 days each. This study will evaluate intake, digestibility, fermentation parameters, nitrogen balance, and ruminal microbial diversity. In the second experiment, to assess performance and enteric methane emission, 48 young bulls Nellore cattle with an initial average body weight (BW) of approximately 230 ± 40 kg will be used. The animals will be distributed in randomized blocks (body weight: light, medium, and heavy) in a factorial arrangement (2x2: Factor A - salt and pulp; Factor B - with tannin, without tannin), consisting of four treatments and three replications (paddocks), totaling 12 experimental units. The treatments for both experiments will be: T1 - salt (0.003% of BW); T2 - salt (0.003% of BW) + tannin (2.5 g/animal/day); T3 - citrus pulp (0.3% of BW); T4 - citrus pulp (0.3% of BW) + tannin (2.5 g/animal/day). Thus, the effects of energy supplements, with or without tannin, will be evaluated in growing animals, and how these treatments affect nitrogen use efficiency and, consequently, animal performance, nitrogen balance, and enteric CH¿ emissions.