Effects of adaptation to diets without the inclusion of roughage on the ruminal epithelium of feedlot Nellore cattle.

• Grant number: 25/04467-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2025
• End date: April 30, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Daniela Rodrigues de Oliveira
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

This study aims to evaluate different nutritional protocols to adapt confined Nellore cattle to a finishing diet without the inclusion of roughage sources, focusing on the morphology and histology of the ruminal papillae. The hypothesis is that confined Nellore cattle require 21 days, seven days longer than the minimum conventionally proposed, to adapt to finishing diets without any roughage inclusion. A total of 144 non-castrated male Nelore cattle (380 kg) will be used, housed in 36 pens (n = 4 per pen). The experimental design will be a completely randomized block design, with animals grouped by initial body weight and randomly allocated to collective pens according to the following adaptation protocols: 1) [Control] 14-day adaptation using a conventional step-up protocol to a finishing diet containing corn silage; 2) [Restriction 14 days] 14-day adaptation using a restriction protocol to a finishing diet without roughage; and 3) [Restriction 21 days] 21-day adaptation using a restriction protocol to a finishing diet without roughage. Each treatment will consist of 12 pens, which will be considered the experimental units for this study. After 112 days, the animals will be slaughtered, and ruminal epithelium samples will be collected for morphological analysis (number and area of papillae per cm² of ruminal wall, absorptive surface area) and histological analysis (height, area, and width of papillae, as well as keratin thickness and mitotic index of the basal layer). The collected data will be analyzed using SAS through the mixed models procedure (PROC MIXED).