Evaluation of the effect of Cymbopogon citratus on consumption, digestibility, methane emission and energy partition in growing cattle

Abstract

Methane (CH₄) produced by enteric fermentation in cattle is of utmost importance as it contributes to greenhouse gas emissions. This gas is a product of the fermentation that feed undergoes in the rumen, resulting in an energy loss for the animal. So, reducing CH₄ production would lead to a more efficient use of the gross energy ingested, which could be used to transform it into meat or milk and would also reduce CH₄ emissions into the environment. There are several CH₄ mitigation strategies, such as the addition of plants with a high concentration of secondary metabolites, like Cymbopogon citratus (CC). Therefore, the present study aimed to evaluate increasing levels of CC on dry matter intake (DM), nutrient digestibility (DIG), CH₄ production and partition of gross energy intake in growing cattle fed a high forage diet (68.6% forage: 31.4% concentrate). Four heifers (¾ Holstein × ¼ Charolais) with an average initial live weight of 225 ± 64 kg distributed in a 4×4 Latin square design was used. The experimental treatments were: 1) control diet (CO); 2) CO + 30 g CC DM/d; 3) CO + 60 g CC DM/d and 4) CO + 90 g CC DM/d. A 22.4 % and 21.2 % reduction in CH₄ yield (CH₄ g/kg DMI) and Ym factor respectively was observed with the 30 CC treatment compared to CO (P ≤ 0.05). No statistically significant differences were observed for means related with DMI, DIG and partition of gross energy intake (P > 0.05). It is concluded that supplementation with 30 g CC DM/d reduces CH₄ yield without affecting animal performance.