AUTHOR=Jiménez-Ocampo Rafael , Montoya-Flores María D. , Pamanes-Carrasco Gerardo , Herrera-Torres Esperanza , Arango Jacobo , Estarrón-Espinosa Mirna , Aguilar-Pérez Carlos F. , Araiza-Rosales Elia E. , Guerrero-Cervantes Maribel , Ku-Vera Juan C. 

TITLE=Impact of orange essential oil on enteric methane emissions of heifers fed bermudagrass hay

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.863910

DOI=10.3389/fvets.2022.863910

ISSN=2297-1769

ABSTRACT=In this study, the effects of orange essential oil (OEO) on the rumen fermentation, nutrient utilization, and methane (CH4) emissions of beef heifers fed a diet of bermudagrass (Cynodon dactylon) were examined. In vitro incubation experiments were conducted in a completely randomized design with three treatments: control (CTL, no additive), OEO1 (0.25% OEO), and OEO2 (0.5% OEO). A substrate of forage and concentrate in a 70:30 dry matter (DM) ratio was used in all treatments. No changes were observed in rumen pH, proportions of volatile fatty acids, and the acetate:propionate ratio (P > 0.05). The addition of 0.25% OEO resulted in a reduction in CH4 production (mL/g) relative to the control (P < 0.05). An in situ study was conducted with 5 g of total mixed ration (TMR) for 6, 12, 24, 48, and 72 hours of incubation. Potential degradability 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 different treatments in a replicated 3 × 3 Latin square design (21-day periods). Heifers were fed TMR at 2.8% of their body weight with no additive (CTL), 0.25% OEO (OEO1), and 0.5% OEO (OEO2). CH4 production was measured in open-circuit respiration chambers. Reductions in gross energy consumption, apparent total tract digestibility, and rumen valerate concentration were observed in the OEO2 treatment (P < 0.05). Additionally, decreases in CH4 emissions (g/d; P < 0.05) and CH4 (MJ gross energy intake/d; P < 0.05) were observed in response to supplementation of 0.5% OEO compared with the CTL treatment. Thus, inclusion of OEO as a feed additive at 0.5% of the TMR reduced CH4 emissions by 12% without modifying fermentation patterns or dry matter intake in heifers fed bermudagrass hay as a basal ration.