Effect of different roughage and physically effective neutral detergent fiber inclusion on ruminal pool sizes and neutral detergent fiber turnover rate in feedlot Nellore cattle

• Grant number: 24/22252-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2025
• End date: May 31, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Murillo Ceola Stefano Pereira
• Grantee: Júlia Goia Ferreira
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil
• Associated research grant: 21/09227-4 - Minimum physically effective Neutral Detergent Fiber (peNDF) requirement for feedlot cattle fed high-concentrate diets, AP.JP

Abstract

The objective of this study will be to evaluate the effect of different roughage and physically effective neutral detergent fiber (peNDF) inclusion on ruminal pool sizes and neutral detergent fiber (NDF) turnover rate in feedlot Nellore cattle. Eight cannulated Nellore yearling steers (450 kg), will be housed in individual pens (21 m2). The study will be conducted as 4 × 4 Latin squares balanced for carry-over effects with 2 × 2 factorial arrangement of treatments, with the following factors: roughage inclusion (10% vs. 15% of dry matter [DM] of the diet) and peNDF inclusion (5.05 % vs. 7.14 % of DM). Corn will be harvested to whole-plant silage, from a single field, chopped to a theoretical chop length of 2.0 mm (5.05 %) or 9.0 mm (7.14). Each Latin square period will consist of 21 days. A step-up adaptation protocol, with five diets containing 65%, 70%, 75%, 80%, and 85% of concentrate feedstuff, will be fed over 25 days (5 days each). The finishing diets will be composed of 85% and 90% concentrated feedstuff, according to the respective treatment. Therefore, the total duration of the study, with adaptation and experimental period, will be 109 days. The reticulo-ruminal contents will be completely evacuated 3 hours before feeding (0500 hours) on days 21 and 1 of each period. At each evacuation, the total reticulo-ruminal digesta weight will be recorded. Thus, will be evaluated in this study: 1) reticulo-ruminal pool; 2) NDF; undigested NDF, potentially degradable NDF; 3) ruminal passage rate; 4) ruminal degradation rate.