However, in other trials, concentrate supplementation to cows grazing high-quality species improves milk production and quality and reduces the intensity of enteric CH 4 emissions. In addition, other studies are focused on traits with the potential for predicting CH 4 emissions, such as feed intake, feed efficiency (residual feed intake) and energy balance. There is currently much interest in further studies to identify individuals within the breeds with functional characteristics for lowering enteric CH 4 emissions. found that Holstein cows present higher enteric CH 4 emissions than Holstein × Zebu crossbreds (419 vs. Previous studies indicate that genetic backgrounds have an influence on enteric CH 4 emissions, which might be associated with the live animal weight and level of milk production.

However, F1 cows tended to show lower enteric CH 4 emission and Y m, compared to those with more Bos taurus genes. In conclusion, non-significant differences in enteric CH 4 emissions and Y m were detected among dairy cows with different genetic backgrounds. Cows with the highest proportion of Bos taurus genes presented a higher annual mean methane conversion factor (Y m), with 7.22, 7.05 and 5.90% for the Triple cross, purebred Jersey and F1, respectively. Pasture DMI and the intensity of CH 4 emissions (g kg −1 DMI) differed ( p < 0.05) between dry and lactating cows, with higher DMI in the lactation period, while CH 4 emission intensity was higher for dry cows. Enteric CH 4 emissions did not differ ( p > 0.05) among genetic groups, although it varied with the stage of lactation, due to differences in milk yield and dry matter intake (DMI). Enteric CH 4 emissions were measured in all cows for 15 months, at the middle of each month, using the SF 6 technique. Sixteen cows belonging to the following three genetic groups were selected for this study: seven F1 (50% Jersey × 50% Gyr), five Triple cross (50% Jersey × 31% Holstein × 19% Sahiwal) and four Jersey.

The aim of the present study was to assess the emission of enteric CH 4 in dairy cows with different genetic backgrounds. Among the options to reduce such emissions, animal genetics is one of the factors that is taking relevance in recent years. Enteric methane (CH 4) is one of the main greenhouse gases emitted in livestock production systems with ruminants.

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