Methane emission and metabolic heat production of Nellore cattle

Abstract. The aim of this study was to evaluate the methane emission (eCH4, g h-1) of Nellore cattle and to study the relationship with metabolic heat production (q”met, W m-2) and meteorological conditions. The study was conducted in the Animal Biometeorology Laboratory of the SA£o Paulo State University, Jaboticabal, Brazil. Five Nellore cattle with an average live weight of 750 kg and similar age and body condition were evaluated. A latin square experimental design was used (5classes of hours (8-10h; 10-12h; 12-14h; 14-16h; 16-18 h) x 5 days), , that was replicated four times, totaling 20 days of data collection. The CH4 emission (eCH4, g h-1) and the metabolic heat production (q”met, W m-2) were measured using an indirect calorimetry system with a facial mask adjusted on the animals‘ muzzle. The air temperature (TA,°C) and humidity (RH, %) were measured in one second intervals and the solar radiation (GS, W m-2) were measured in intervals of ten minutes. During the observations the means of TA,RH and GS were 30.15±0.02 °C, 60.91±0.09% and 530.73±2.71 W m-2 respectively. Between 8 am and 12:00 pm, Nellore cattle emitted more (P 0.05). The eCH4 had positive and high correlations with RH,q”met and GS (0.5042, 0.3571 and 0.1455, respectively) and a negative correlation with TA (-0.4401).