Roughage and physically effective neutral detergent fiber inclusion in finishing diets fed to feedlot cattle on ruminal fermentation and motility, bacterial community composition, eating behavior, and total tract digestibility

• Grant number: 24/14012-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: April 01, 2025
• End date: March 31, 2027
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Murillo Ceola Stefano Pereira
• Grantee: Gabriela Mariana Fogaça
• 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 roughage and physically effective neutral detergent fiber (peNDF) inclusion in finishing diets fed to feedlot cattle on ruminal fermentation and motility, bacterial community composition, eating behavior, and total tract digestibility. Eight cannulated Nellore yearling steers (450 kg), will be housed in individual pens (21 m2). The study will be conducted as a 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 of the diet) and peNDF inclusion (low vs. high peNDF). Corn will be harvested to whole-plant silage, from a single field, chopped to a theoretical chop length of 2.0 mm (low peNDF) or 9.0 mm (high peNDF). Each period of the Latin square will consisted of 21 days including 14 days without sampling and 7 days of sampling. The study will last 84 days. Ruminal pH measurement will initiate on day 17 and will proceed for the subsequent 96 h of each experimental period. Ruminal digesta samples will be collected on day 17 and every 12 h thereafter with a 3 h offset on subsequent days until day 21 to measure short-chain fatty acids and ammonia. Reticulo-ruminal contents will be completely evacuated 3 h before on days 21 and 3 h before feeding on day 1 of each experimental period to evaluate the rate of ruminal NDF turnover. Ruminal motility will be measured over 4 hours, starting at 10 am and ending at 2 pm on days 15 and 16 of each experimental period. Ruminal digesta samples will be collected on day 18 of each experimental period to evaluate ruminal bacterial community composition. Eating behavior will be recorded using a digital video camera from days 17 to 21 of each experimental period. From days 17 to 21 of each experimental period, fecal samples will be collected to evaluate total tract nutrient digestibility using titanium dioxide as a marker to predict fecal output.