Rumen epithelium cell proliferation of feedlot Nellore cattle fed different feed additives

Abstract

The aim of this study is to analyze the cell proliferation of the rumen epithelium in feedlot Nellore cattle, evaluating different feed additives. In experiment 1, 72 Nellore bulls will be used, with average initial live weight of 370kg. The treatments will be: 1- Monensin (30mg / kg) in the adaptation and finishing periods, 2- Monensin (30mg / kg) + Virginiamycin (25mg / kg) in adaptation and only Virginiamycin (25mg / kg) in the finishing periods; 3- Monensin (30mg / kg) + Virginiamycin (25mg / kg) in the adaptation and finishing periods; 4- Virginiamycin (25mg / kg) in the adaptation and Monensin (30mg / kg) + Virginiamycin (25mg / kg) in the finishing period. There will be 6 replications (pens) for each treatment in a randomized block design. In experiment 2, 96 Nellore bulls will be used, with average initial live weight of 370kg. The division of the animals will be randomly into 24 bays, with four animals per pen. The treatments will be: 1- Control (no additives); 2- Monensin (30ppm); 3- Functional Oil (500ppm); 4- Monensin + Functional oil (30ppm and 500ppm respectively). Also, in this study, there will be 6 replications (pens) for each treatment in a randomized block design with a 2x2 factorial arrangement. After slaughter, the rumens of all animals will be emptied and washed, and then samples from the ventral sac of rumen epithelium of each animal will be collected for performing cell proliferation assays utilizing Immunohistochemistry technique, following the method of Estevam et al. (2014), adapted from Pereira et al. (2010).