Abstract

Mitigation of ruminant methane is an important component of New Zealand’s strategy to lower greenhouse gas emissions. Methods for mitigation must be profitable, easily achievable for producers and be applicable to a wide range of farming systems and topography. The rumen ionophore monensin, is potentially capable of meeting these requirements, but its effects on both production and methanogenesis have been variable with forage diets.A trial was undertaken with 60 lactating Friesian/Holstein dairy cows in early – mid lactation and fed pasture over a 3 month period, to measure effects of a commercially available monensin controlled release capsule (CRC) on milk production, rumen metabolites and methane production. Monensin had no effect on fat or protein yield and therefore milksolids yield, 1.68 kg/day for both groups of cows, was unaffected. Rumen volatile fatty acid ratios, measured in 10 animals, were not affected by monensin treatment and average methane production (323 g/day) was similar for both groups (P=0.961). The absence of benefits from monensin for either production or methane mitigation in dairy cows fed forages as a sole diet are in line with other published data. Monensin CRCs will not provide a profitable route for methane mitigation in ruminants grazed on pasture.

GC, Waghorn, H Clark, V Taufa, and A Cavanagh

Proceedings of the New Zealand Society of Animal Production, Volume 67, Wanaka, 266-271, 2007