Cell proliferation and apoptosis of rumen epithelium of feedlot Nellore cattle adapted with different protocols

• Grant number: 11/21682-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2012
• End date: June 30, 2013
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Daniela Dutra Estevam
• Host Institution: Universidade Estadual Paulista (UNESP). Campus Experimental de Dracena. Dracena , SP, Brazil

Abstract

The objective of this study is to evaluate the length of different protocols of adaptation to high concentrate diets on cell proliferation and apoptosis of rumen epithelium of feedlot Nellore cattle. One hundred twenty Nellore yearling bulls (385 kg) backgrounded on pasture will be randomly allocated in 24 pens with five animals per pen (5,4 m² and 0,8 m bunk per animal) according to the treatments: step-up program during 9 days (S9), step-up program during 14 days (S14), restriction program during 9 days (R9), and restriction program during 14 days (R14), characterizing a completely randomized design with a 2 x 2 factorial arrangement of treatments (2 protocols of adaptation lasting 9 and 14 days) with repeated measures over time, which will be taken at the end of adaptation and finishing periods. There will be 6 replications (pens) per treatment. The step-up program will consist of ad libitum feeding of three adaptation diets over periods of 9 or 14 days with concentrate level increasing from 55% to 85% of diet dry matter. The restriction program will consist of restricted intake of the final diet (85% concentrate) with programmed increases in feed offered until yearling bulls reached ad libitum access over periods of 9 or 14 days. The diet will be offered twice daily (8h and 15h). The animals will be fed the same finishing diet, which will contain 85% concentrate, after the period of adaptation until they achieve at least 490 kg of body weight and 4 mm of subcutaneous back fat, when they will be slaughtered. After slaughter rumens from all animals will be evacuated and washed, and fragments of 1 cm2 from ventral sac will be harvested for future immunohistochemistry analysis. The blades obtained by immunohistochemistry reaction will be analyzed in terms of morphometric measures and photo-documented by light and fluorescence microscopy to study and quantify cell proliferation and occurrence of apoptosis.(AU)