Nitrous oxide emission from excreta of different beef cattle breeds finished in feedlot

Abstract

The objective of this work was to compare nitrous oxide (N₂O) emissions from urine and manure of Nellore and crossbred (Nellore x Angus) cattle finished in feedlot. Twenty Nellore and 20 crossbred bulls were fed a diet consisting of 75% concentrate and 25% roughage. Excreta were applied to the pens after 43 days of confinement, when N₂O monitoring started through static chambers. The data were subjected to the analysis of variance, and averages were compared by Tukey’s test. The N₂O fluxes from urine and manure were similar among the breeds, with important peaks after rain events. The cumulative emissions of N₂O from urine per kilogram of body weight gain (BWG) and the total emissions from manure per kilogram of BWG were 22.7% and 24.4% higher in Nellore cattle. There is no breed effect on N₂O flux and cumulative emissions by excreta from confined beef cattle; however, the crossbreed emits less per kilogram of BWG. There is a high correlation between rainfall volume and the N₂O emissions of the next day, which indicates a period between rain occurrence and the increase in N₂O emission.