Effect of physically effective neutral detergent fiber and starch inclusion on total tract digestibility in feedlot Nellore cattle

• Grant number: 25/00610-0
• 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: Pedro Trevisan Tonelli
• 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

Roughage should be included at reduced levels in high-concentrate diets due to lower nutritional composition, higher operating costs and to maximize energy intake during the feedlot period. Therefore, optimizing roughage levels in high-concentrate diets is necessary to improve animal performance. Thus, this study aimed to test the effect of physically effective neutral detergent fiber (peNDF) and starch inclusion on total tract digestibility in feedlot Nellore cattle. Eight Nellore yearling steers (450 kg), previously fit with a cannula, 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: peNDF (low [8.48 of dry matter [DM] of the diet] vs. high [10.26% of DM of the diet]) and starch inclusion (22.5% vs. 45% of DM of the diet). 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. Titanium dioxide will be used as a marker to predict fecal production and will be included at 0.20% of the DM of the diet from day 12 to 21 of each experimental period. From day 17 to day 21 of each experimental period, fecal samples (200 g) will be collected directly from the rectum of each animal (d 17 at 07:00 and 19:00; d 18 at 10:00 and 22:00; d 19 at 13:00; d 20 at 01:00 and 16:00; and 21:00 at 04:00), representing a 24-h feeding cycle, collected every 3 h. At the end of each collection period, 8 fecal samples will be composed into a single sample per period. Thus, this project will evaluate total tract digestibility of DM, organic matter, crude protein, starch, neutral detergent fiber, acid detergent fiber, and hemicellulose.