Morphology and histology of rumen epithelium of feedlot Nellore cattle adapted with different protocols

• Grant number: 11/03431-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2011
• End date: May 31, 2012
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Tassia Veluma Barbosa Carrara
• Host Institution: Universidade Estadual Paulista (UNESP). Campus Experimental de Dracena. Dracena , SP, Brazil

Abstract

The objective of this study will be to evaluate the length of protocols of adaptation to high concentrate diets on morphology and histology of rumen papillae of Nellore cattle finished in feedlot. 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 6 replications (pens) per treatment. Measures over time will be taken at the end of adaptation, and at the end of finishing period. The step up program consisted 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 consisted 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. Experimental diets will be fed twice daily (8h and 15h). After the adaptation period all the animals will be fed the finishing containing 85% concentrate until reaching 490 kg of body weight and at least 4 mm of back fat thickness, when they will be slaughtered. It will performed macroscopical and microscopical morphologic analysis, such as number and mean area of papillae and rumen wall absorptive surface area in cm2, as well as histologic evaluations such as papillae height, area and height of rumen epithelium queratinized layer, and determination of mitotic index. (AU)