Effects of whole cottonseed in finishing Nelore feedlot cattle diets on performance, carcass characteristics, ruminal metabolism and nutrients digestibility.

Abstract

The project aims to assess the use of different levels of whole cottonseed in diets containing high levels of concentrate for Nellore cattle finished in feedlot. For this, three experiments will be conducted. In experiment 1 (performance) will be assessed 5 levels of inclusion of whole cottonseed (0, 8, 16, 24 and 32%) in dry matter (DM) of diets (isonitrogenous) containing 85% concentrate. Will be used 300 Nelore bulls to evaluate performance (DM intake, daily weight gain and feed efficiency) of the quantitative data of the carcass (hot carcass weight, cold carcass weight, dressing percentage, ribeye area, thickness of sub-cutaneous fat and pH) and meat quality (fatty acid profile, flavor (sensory analysis), composition, color, shelf life, and gossypol content of cholesterol), and sanguíeos parameters (glucose, insulin, triglycerides, cholesterol and liver enzyme gamma-glutamyl transferase). In experiment 2 (metabolism) will be used five steers Nellore, cannulated in the rumen and allotted to a 5x5 Latin square design. Will be assessed the same five levels of inclusion of whole cottonseed in the diets of experiment 1 on dry matter intake, nutrient digestibility, ruminal parameters (pH, production of volatile fatty acids and ammonia), the synthesis of microbial protein the blood parameters (glucose, plasma urea, insulin and cholesterol), excretion and nitrogen balance, and ingestive behavior of animals. In experiment 3 (in situ) will evaluate the kinetics of in situ ruminal degradation of DM, neutral detergent fiber (NDF), acid detergent fiber (ADF)and crude protein (CP) of diets