Effect of a natural additive rich in thyme essential oils on the emission of enteric methane and on production performances of cattle

Abstract

The objective of the present study is to evaluate the effect of the incorporation, in the feed ration, of natural additive rich in phenolic essential oils based on thyme, on the emission of enteric methane in dairy cows. In a second step, the study consists in evaluating the effect of the same additive on the performances of cattle, namely milk production yield in lactating cows and the average daily gain in feedlot cattle. The study measured methane production before and after the addition of the feed additive to the diet of five Holstein cows. After two weeks of adaptation to the diet, methane production was measured by the respiratory mask method. Then, 50 g of the product rich in thyme essential oils was added to the ration, which means 7.15 g/kg dry matter, and a second methane measurement was performed after two weeks of adaptation. The addition of the product to the cows' diet resulted in an average reduction of 21% in the amount of enteric methane emitted. In a second step, the same product was used to test its effect on live weight gain in feedlot bulls. In this respect, ten bulls from a fattening farm were tested. Five received 70 g of the additive in their feed ration and five served as controls. The bulls that received the feed additive showed a higher average daily gain compared to the control group. The results obtained were highly significant (p<0.01), with means of 1.55 ± 0.058 kg for the control group vs 1.88 ± 0.177 kg for the group that received the additive. To test the effect of the same feed additive on milk production, a third trial was conducted. Eight Holstein cows were divided into two homogeneous groups. Four received 100 g of the product rich in essential thyme oil in their feed ration and four served as a control group. An increase in daily milk production was noted in all cows receiving the additive compared to the control cows. The results of the average amounts of milk produced per liter per day were statistically significant (p<0.05), with averages of 15.38±1.32 l/d for the control group and 19.17±1.96 l/d for the group with the additive. Milk fat was also improved in the cows supplemented with the additive, with an average of 3.54±0.26 g/100 g in the control group vs 3.66±0.34 g/100 g of milk in the group with the additive. However, the results obtained for the milk fat showed no statistic significance (p>0.05). The trials undertaken during this study allowed to verify the interest and the relevance of the use of the tested natural feed additive, not only for the decrease of enteric methane emission and the preservation of the environment, but also for its beneficial effects on cattle productions.

 Keywords: Cattle, essential oils, thyme, greenhouse effect, methane, performance