Abstract #T111

# T111
Effect of the supplementation level with concentrate on milk and methane production in crossbreed tropical dairy cows grazing tropical pastures.
L. E. Robles-Jimenez1, A. Xochitemol2, M. Benaaouda1, L. Corona2, E. Castillo2, O. A. Castelan-Ortega1, M. Gonzalez-Ronquillo*1, 1Universidad Autonoma del Estado de Mexico, Toluca, Mexico, Mexico, 2Universidad Nacional Autónoma de México, Ciudad de México, Mexico.

The objective of this study was to evaluate the level of supplementation with concentrate in dairy cows grazing native pastures in milk production, and estimate methane (CH4) and nitrous oxide (N2O) emissions. The study included 12 crossbred F1 dairy cows (1/2 Bos taurus 1/2 Bos indicus) over 60 d of lactation. Cattle grazed tropical grasses (Paspalum spp., Axonopus spp., Brachiaria spp. and Cynodon neumfluensis) and supplemented with 0, 0.150, 0.300 and 0.450 kg of concentrate (kg DM / kg daily milk production) in 3 periods of 15 d each one in a crossover design (all animals receive all treatments). N2O emissions from excreta and urine were calculated (IPCC, 2006). The quantity of daily CH4 production were calculated (kg·head−1·day−1) (IPCC, 2006). Data were analyzed with the SAS MIXED procedure and the means were subjected to a trend analysis using orthogonal polynomials. There were no differences (P > 0.0001) for live weight and milk yield production between treatments. The supplementation with concentrate in tropical dairy cows did not increase milk yield (Table 1) but increased CH4 and N2O (P < 0.0001) excretion per cow. The use of concentrates in crossbreed F1 dairy cows fed with native tropical pastures affects negatively the emission of greenhouse gases, producing more CH4and N2O per cow per day; however, cows supplemented present a higher concentrate intake, which means more gross energy intake and higher DMI, without increase milk yield production. Table 1 (Abstr. T111). Dry matter intake (DMI), milk yield production, CH4 and N2O production in F1 crossbred dairy cows grazing, supplemented with different levels of concentrate (kg/kg daily milk production) in humid tropics
Live weight (LW0.75)108.5107.6109.1109.90.390.7403
DMI, kg/d12.7812.5712.3513.430.120.2113
GE intake (MJ/d)212.7b217.2b219.3b251.9a2.860.0001
Milk yield kg, FCM 3.5%
CH4 g/cow/d390.5398.7b402.5b462.5a4.090.0093
N2O g/ cow/d61.1c67.4bc69.3b82.6a1.230.0001

Key Words: greenhouse gases, methane, crossbreed