Enteric methane emission from beef cattle fed diets containing crude glycerin associated with energy sources

Abstract Text: The objective of this study was to evaluate the enteric methane emission of Nellore young bulls finished in feedlot fed diets containing 10% crude glycerin (CG; DM basis) replacing corn or soybean hulls, with or without a source of oil. Twenty eight Nellore young bulls with 395 ± 32 kg of average initial body weight and 20 ± 2 months were distributed in a completely randomized design with four experimental treatments and seven replications in a 2 x 2 factorial arrangement (high or low starch, with or without a source of oil). The treatments were: T1 - CG with high starch (corn), T2 - CG with low starch (soybean hulls), T3 - CG with high starch and a source of oil (corn and soybeans) and T4 - CG with low starch and a source of oil (soybean hulls in soybean grain). All treatments contained 60% corn silage and 40% concentrate. The sulfur hexafluoride SF₆ tracer method was used to measure eructated CH₄. Data were analyzed using the PROC GLM procedure of SAS with significance level at P<0.05. Methane emission was expressed per day (g CH₄ day^-1), per kilogram of carcass produced (g CH₄ kg CAR^-1) and per kilogram of average daily gain (g CH₄ kg ADG^-1). Differences were not detected between treatments for all variables (P>0.05). However, when compared the effects between factors, differences were detected, with average values of 118.74 and 164.40 g CH₄ day^-1 (P<0.001), 101.93 and 140.78 g CH₄ kg ADG^-1 (P<0.01), 141.14 and 180.46 g CH₄ kg CAR^-1 (P<0.02) to the factors with or without a source of oil, respectively. The starch in the diet did not affect enteric methane emission for all variables (P>0.05). However, may be affected when an oil source with crude glycerin is added in diet Nellore young bulls finished in feedlot.

Keywords: environment, glycerol, ruminant