The effect of varying levels of coconut oil on intake, digestibility and methane output from continental cross beef heifers

This experiment sought to establish the response to increasing levels of coconut oil (CO) supplementation with a fixed 0.50:0.50 forage:concentrate diet on intake, digestibility and methane (CH4) emissions. Sixteen continental cross beef heifers (mean starting weight 481 +/- 36 kg) were assigned randomly to one of four levels of CO; 0 g/day, 125 g/day, 250 g/day or 375 g/day in an incomplete (three periods) multiple (no. = 4) Latin-square design experiment (no. = 12 per treatment). A linear reduction in CH4 output occurred as the level of CO in the diet increased (P < 0.001) with the greatest reduction at the 375 g/day level (394, 341, 314 and 2401/day for animals fed 0, 125, 250 and 375 g/day CO, respectively). As the level of CO increased dry-matter (DM) intake (DMI) decreased, however these differences were only statistically significant at the 375 g/day level (P < 0.001). The proportional reduction in CH4 output was greater than the proportional reduction in DMI and hence CH4 l/kg DMI decreased from 39.8 l/kg when no CO was given to 29.7 l/kg when 375 g/day CO was given. The addition of CO to the diet resulted in a significant decline in dry-matter digestibility (DMD) at the 375 g/day level (P < 0.05). These data demonstrate that the inclusion of CO at levels from 0.013 to 0.045 of the dietary DM within a 0.50:0.50 silage and concentrate ration reduces CH4 production with no adverse effect on DMI or DMD up to the 250 g/day level (0.027 of dietary DM).