Impact of orange essential oil on enteric methane emissions of heifers fed bermudagrass hay
Rafael Jiménez‐Ocampo, María Denisse Montoya-Flores, Gerardo Antonio Pámanes-Carrasco, Esperanza Herrera-Torres, Jacobo Arango, Mirna Estarrón‐Espinosa, Carlos Fernando Aguilar-Pérez, Elia Esther Araiza-Rosales, M. Guerrero-Cervantes, Juan Carlos Kú-Vera
Abstract
In this study, the effects of orange essential oil (OEO) on the rumen fermentation, nutrient utilization, and methane (CH 4 ) emissions of beef heifers fed a diet of bermudagrass ( Cynodon dactylon ) were examined. In addition, in vitro and in situ experiments were conducted. The in vitro experiment consisted of three treatments: control (CTL, no OEO), OEO1 (0.25% OEO), and OEO2 (0.5% OEO). The forage to concentrate ratio was 70:30 (dry matter [DM] basis) in all treatments. No changes in pH, proportions of volatile fatty acids, and the acetate:propionate ratio were observed ( P > 0.05). The addition of 0.25% OEO resulted in a reduction in CH 4 production (mL/g) relative to the control ( P < 0.05). In the in situ experiment, 5 g of total mixed ration (CTL, OEO1, and OEO2) were incubated for 6, 12, 24, 48, and 72 h. Potential and effective degradability were not affected by OEO supplementation ( P > 0.05). In the in vivo study, six crossbred beef heifers ( Bos indicus × Bos taurus ), fitted with rumen cannulas, were assigned to three different treatments: no additive (CTL), 0.25% OEO (OEO1), and 0.5% OEO (OEO2) in a replicated 3 × 3 Latin square (21-day periods). Heifers were fed at 2.8% body weight. In vivo CH 4 production was measured in open-circuit respiration chambers. Reductions in gross energy consumption, apparent total tract digestibility, and rumen valerate concentration were observed for OEO2 compared to the control ( P < 0.05). Additionally, decreases in CH 4 emissions (g/day; P < 0.05) and CH 4 (MJ gross energy intake/day; P < 0.05) were observed in response to supplementation of 0.5% OEO as compared to the CTL treatment. Thus, supplementation of 0.5% OEO reduced CH 4 emissions (g/day) by 12% without impacting the DM intake of heifers fed bermudagrass hay as a basal ration.