Ruminal fermentation pattern and nutrients degradability of cannulated Nellore cattle fed combinations of virginiamycin and sodium monensin to increase carcass weight

Abstract

The objective of this study is to evaluate the ruminal fermentation pattern, protozoa counts, ruminal degradability of nutrients, rumen solids disappearance rate, feeding behavior and particle sorting of cannulated Nellore cattle fed with different combinations of sodium monensin (MON) and virginiamycin (VM) during adaptation and finishing periods in the feedlot. Five Nellore rumen cattle will be used in 5 x 5 Latin square, where each period will be composed of 28 days + 7 days of washout, with the following treatments: 1) MON (30 mg/kg) during the entire feeding period; 2) VM (25 mg/kg) during the entire feeding period; 3) VM (25 mg/kg) + MON (30 mg / kg) during the adaptation period and only VM (25 mg/kg) throughout the finishing periods 1 and 2; 4) VM (25 mg/kg) + MON (30 mg/kg) over the entire feeding period; and 5) VM (25 mg/kg) + MON (30 mg/kg) during the adaptation and finishing period 1, and only VM (25 mg/kg) during the finishing period 2. The adaptation period will last 14 days for all treatments just described. The following variables will be evaluated in this study: ruminal degradability of nutrients, such as starch and NDF; feeding behavior and particle sorting; rumen pH, temperature and oxi-redox potential via data logger; protozoa counts; molar proportion of short-chain fatty acids, as well as rumen concentrations of lactate and ammonia. At the end of each experimental period, it will be evaluate the rumen solids disappearance rate as well. (AU)