The effect of pelleting of alfalfa hay on methane production and digestibility by steers

A modified 2 × 2 factorial experiment with 19 steers was used to study methane (CH4), CO2 and heat production and O2 utilization and the energy digestibility of pelleted and chopped first- and second-cut alfalfa at maintenance and 1.6 times maintenance in steers. Methane production, dry matter digestibility and urinary energy loss were reduced (P < 0.05) when first-cut alfalfa was pelleted but pelleting had no influence on these parameters with second-cut alfalfa. Methane and CO2 production and O2 utilization increased sharply after feeding. There were interactions between type of feed (chopped vs. pelleted) and cut of alfalfa in CH4 (1 kg−1 feed DM) and CO2 production and O2 utilization. Energy digestibility and CH4 losses were similar at maintenance and 1.6 times maintenance level of feeding. Although methane production was lower in cattle fed pellets in three out of four comparisons of pelleted and chopped hay diets, the decline in energy loss as CH4 due to pelleting was not sufficient to justify the extra energy expended to pellet diets from an environmental or economic point of view.