Inclusion of dried distillers grains with solubles in feedlot diets containing flint corn and citrus pulp: metabolism and performance of finishing Nellore bulls

• Ano de defesa: 2024
• Autor(a) principal: Benez, Lívia Marques
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Bos indicus; Brasil; Brazil; Carcass quality; Caroço de algodão; Qualidade da carcaça; Whole cottonseed
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/11/11139/tde-10012025-171012/

Given the increasing availability of dried distillers grains with solubles (DDGS) in Brazil and the scant research on its use in conventional confinement diets in the Southeast regionwhere diets typically include flint corn, citrus pulp, and whole cottonseedthere is a compelling need to investigate the optimal levels of DDGS inclusion in these diets. The objective of the study was to compare the performance (Experiment 1) and metabolism (Experiment 2) of Nellore bulls finished with diets containing 0, 10, 20, 30, or 40% DDGS in dry matter (DM) in total replacement of whole cottonseed and partial replacement of ground flint corn and citrus pulp. In Exp. 1, 368 Nellore bulls blocked by initial shrunk body weight (SBW=420&#177;30 kg) were allocated in 60 experimental pens (n=12 pens per treatment) for 100 days, post the adaptation period to evaluate their growth performance, the diet observed net energy for maintenance (NEm) and gain (NEg), as well as carcass characteristics. In Exp. 2, 30 rumen-cannulated Nellore bulls (SBW=503&#177;46 kg) were kept in individual pens for 21 days (n=6 animals per treatment), to evaluate ruminal parameters and apparent digestibility of nutrients in the total tract. Both experimental designs were randomized blocks, and the data were analyzed using R (ver. 4.3.1). From Exp. 1, linear increases were observed in carcass adjusted final SBW (P<0.001), hot carcass weight (HCW; P<0.001), and dressing percentage (DP; P<0.001) with an incremental inclusion of DDGS in the diets. For every ten percent unit inclusion in this type of diet, HCW was increased by 2.62 kg. Additionally, the inclusion of DDGS resulted in linear increases in diet observed NEm (P=0.001) and NEg (P=0.001). From Exp. 2, digestibility exhibited linearly decreasing effects with the inclusion of DDGS for DM (P=0.004), organic matter (OM; P=0.004), neutral detergent fiber (NDF; P=0.01), acid detergent fiber (ADF; P=0.04), and total digestible nutrients (TDN; P=0.004). We also observed linear increases for isobutyrate (P=0.004) and isovalerate (P=0.002) as the DDGS level in the diet increased. The inclusion of DDGS up to 40% in the diets to replace mixtures of whole cottonseed, flint ground corn, and citrus pulp increases diet contents of net energy and the performance of Bos indicus bulls. Studies of nutrient digestibility and rumen fermentation are not able to demonstrate the energetic superiority of DDGS compared to the mixtures of whole cottonseed, flint ground corn, and citrus pulp.