Modification of methane emission in sheep by cysteine and a microbial preparation.

Modification of methane emission from ruminants by the use of L-cysteine and/or a microbial preparation in wethers fed lucerne hay was assessed in an open circuit respiratory trial according to a 4 x 4 Latin squared design. L-Cysteine (0.1 g kg-1 W0.75, as sulphur equivalent) was drenched daily to wethers as an aqueous solution of hydrochloride. The microbial preparation was a dried mixture of Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis, Pseudomonas fluorescens, Streptomyces cellulosae, Streptomyces albidoflavus and Saccharomyces lypolyticum. The microbial preparation was added at 87 mg kg-1 metabolic weight (W0.75) to the daily diet of a wether sheep offered lucerne chaffed hay at a maintenance level of 54 g DM kg-1 W0.75. L-Cysteine suppressed methane emission from the sheep by 13% whereas the microbial preparation actually increased methane emission by 18%. Oxidation-reduction potential, pH, ammonia and VFA were non-significantly influenced by the applied treatments.