The fiber level adjust in feedlot diet is dependent on their previous nutritional plane

• Grant number: 24/23260-2
• Support Opportunities: Regular Research Grants
• Start date: May 01, 2026
• End date: April 30, 2028
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Rodrigo Silva Goulart
• Grantee: Rodrigo Silva Goulart
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• City of the host institution: Pirassununga
• Associated researchers: Hilário Cuquetto Mantovani ; Ives Cláudio da Silva Bueno ; Paulo Henrique Mazza Rodrigues ; Saulo da Luz e Silva

Abstract

Fiber levels in feedlot diets fed Nellore cattle could be influenced by the animals' nutritional background during the growing phase. During this period, the adopted nutritional strategy can modulate the ruminal microbiome and directly affect performance and rumen health during the finishing phase. However, the relationship between nutritional background and optimal fiber levels in finishing diets remains underexplored. The aim of this study is to evaluate the effects of different nutritional plans during the growing phase and varying fiber levels during finishing on performance, carcass traits, ruminal microbiota, and ruminal health in Nellore cattle. A total of 112 non-castrated Nellore males will be used, divided into two groups during the growing phase: traditional (low-quality hay and mineral salt) and intensive (corn silage and protein supplementation). Following the growing phase, animals will be fed with diets containing 10%, 15%, or 20% neutral detergent fiber from forage (on DM basis) during the finishing phase. Complementary experiments will be conducted with 24 cannulated animals to analyze ruminal microbiota, ruminal pH, and metabolic parameters. The analyses will include DNA sequencing for microbiome characterization, continuous ruminal pH monitoring using intra-ruminal sensors, and performance. Samples of ruminal content, blood, and tissues will be collected for biochemical and histological analyses. Carcass data will include weight, yield, and qualitative characteristics of the meat. Furthermore, meat samples will be. The expected outcomes include the identification of optimal fiber levels for different nutritional backgrounds, improved feed efficiency and maintained rumen health. This study aims to advance the development of tailored diets, contributing to the sustainability and productivity of the national cattle industry. The findings have significant potential for publication in high-impact journals and practical applications in the nutritional management of feedlot cattle. (AU)