Heritability of predicted daily enteric methane emissions from growing Nellore cattle
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The objective of this study was to estimate the heritability of predicted daily enteric methane emissions (PME) from growing Nellore cattle. Dry matter intake (DMI) records of 955 Nellore animals that were born between 2004 and 2013, which were obtained in a postweaning performance test lasting 83 +/- 15 days, were used. The PME of each animal, obtained as MJ/day and converted to g/day, was estimated using three equations: PME1 (MJ/day) = 2.29 + 0.647 x DMI (kg/day), PME2 (MJ/day) = 3.96 + 0.561 x DMI (kg/day), and PME3 (MJ/day) = 4.41 + 0.50 x DMI (kg/day). The heritability (h(2)) of PME obtained using the three equations was identical to the h(2) of DMI, regardless of whether the model included the effect of mid-test weight (h(2) = 0.32 +/- 0.069) or not (h(2) = 0.48 +/- 0.069). The equations were based exclusively on variations in DMI, and detected variations in this trait without taking into consideration individual differences in enteric methane emission caused by differences in fermentation and digestion capacity. Therefore, prediction equations of enteric methane emission from DMI are not adequate to estimate differences between animals.