Reduction of enteric methane production with palm oil: Responses in dry matter intake, rumen fermentation and apparent digestibility in sheep

The aim of the trial was to assess the effect of palm oil (PO; Elaeis guineensis Jacq.) in a basal ration of low-quality Pennisetum purpureum grass on DMI, enteric CH4 emissions, rumen fermentation and apparent digestibility in hair sheep. Eight non-castrated male Pelibuey sheep with an average live weight (LW) of 28 ± 1.1 kg housed in metabolic crates inside respiration chambers, were used in a replicated 4 × 4 Latin square design. Each period lasted 18 days (13 days for adaptation to handling and rations, and 5 days for measurements of response variables). A control (CON) ration and three PO levels were evaluated: 20, 40 and 60 g/kg as a percentage of dry matter (DM) in the ration. The basal ration had a 70:30 forage:concentrate ratio (DM basis). Individual DMI was measured daily. Measurement of apparent digestibilities of nutrients was carried out by total collection of feces. Samples of rumen liquor were taken postprandial from sheep, subsequently, the molar proportion of VFA was determined. Enteric CH4 production (L/d) was measured using head boxes. Average intakes of DM per day (855 g/d), DM/kgW0.75 (64 g/d), organic matter (OM; 809 g/d) and crude protein (CP; 106 g/d) were not affected by treatment (P > 0.05). Neutral detergent fiber (NDF) and crude fat (CF) intake were reduced linearly (P < 0.05) as the percentage of PO in the ration was increased. Apparent digestibilities of DM, OM and NDF were not affected by the inclusion of PO (P > 0.05). Molar proportion of propionic acid in the rumen increased linearly as the level of PO inclusion in the ration was augmented (P < 0.05). The acetic:propionic acid ratio decreased linearly (P < 0.01) from 2.02 for the control ration to 1.66 for the ration with 60 g/kg PO. Enteric CH4 emissions decreased with increasing levels of PO in the ration (P < 0.01). Energy loss (MJ/d) as CH4 was reduced (P < 0.01), as well as methane energy loss as a proportion of gross energy intake (Ym; P < 0.01) and CH4 emission per year (EF; P < 0.01). Results demonstrate that PO is a promising by-product for mitigating CH4 emissions in hair sheep fed low-quality tropical grasses, with reductions of up to 14.1 %, without negative effects on DMI, nutrient intake and ration digestibility.