ADAPTATION PROTOCOLS AND VALIDATION OF RUMEN SAMPLING TECHNIQUES IN ALTERNATIVE BEEF CATTLE PRODUCTION SYSTEMS

• Grant number: 25/15681-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: November 01, 2025
• End date: October 31, 2027
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Ariany Faria de Toledo
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil
• Associated research grant: 24/07544-0 - Adaptation to high-energy diets in non-conventional production systems for beef cattle., AP.R

Abstract

This project aims to evaluate different nutritional protocols to adapt beef cattle to high-energy diets in non-conventional production systems: no-forage diets and diets for intensive finishing on pasture (TIP). Three experiments and 1 validation methodological validation (study 4) will be conducted, with the following treatments in studies 1 and 2: 1) Control: 14-day adaptation on step-up to the conventional finishing diet containing forage sources; 2) 14-day restriction: adaptation by quantitative restriction to a finishing diet with no forage; and 3) 21-day restriction: adaptation by quantitative restriction to a finishing diet with no forage. In study 3, about TIP, the treatments will be: 1) 21-day adaptation, with an initial concentrate offer at 0.5% of body weight (BW); 2) 14-day adaptation, with an initial concentrate offer at 0.5% of BW; 3) 14-day adaptation, with an initial concentrate offer at 1.0% of BW. The objective is to reach 2,0% of BW, in terms of concentrate intake, at the of the adaptation period. In studies 1 (n = 144) and 3 (n = 28) variables related to performance, carcass characteristics, feeding behavior, rumen and cecum morphometry, as well as ruminal bacteria and protozoa will be evaluated in Nellore bulls. In study 2, six cannulated Nellore cattle will be used in a duplicated 3x3 Latin square design to evaluate feeding behavior, ruminal nutrient degradability, rumen pH, ruminal fermentation, and ruminal microbiota to study the ruminal metabolism during and after the adaptation period. In this context, Study 4 aims to validate a rumen fluid sampling methodology that is less invasive and allows for practical and frequent assessments throughout the dietary adaptation period. To achieve this, ruminal pH, concentrations of short-chain fatty acids (SCFA), ammonia nitrogen (NH¿-N), ruminal lactate, and the microbial and protozoal populations in rumen fluid obtained via esophageal probe (EP) or ruminal cannula (RC) will be compared. The study also aims to assess the feasibility of replacing the RC, considered the gold standard, but limited to experimental use with the EP as a practical tool for continuous monitoring of ruminal fermentation.