Abstract

Methane (CH4) emissions from 12 Hereford x Friesian steers grazing hill country were measured on six occasions (6, 11, 13, 15, 23, and 26 months of age) during the months of February, July, September, November 2003, and October and November 2004 using the sulphur hexafluoride (SF6) tracer gas technique. These data are the first serial measurements of CH4/kg DMI on growing dairy beef cattle in New Zealand. Average daily methane (± s.d.) emissions increased from 89 (10) g/head/d for 6 month old steers to 222 (46) g/head/d for 26 month old steers. The corresponding dry matter intake (DMI), predicted from energy requirements using the Feeding Standards for Australian Livestock, also increased from 3.6 kg/head/d to 12.0 kg/head/d for 6 and 26 month old steers, respectively. In contrast to the increasing DMI and daily methane emissions with age of the steers, the mean methane emission per unit of estimated intake was relatively constant at 17.3 (3.7) to 19.0 (5.6) g CH4/kg DMI from 11 to 26 months of age with a higher value of to 26.1 (7.0) g CH4/kg DMI for the 6 month old steers. The overall mean value of 19.5 (± 5.2) g CH4/kg DMI is lower than that used in the current national inventory calculations.

G, Molano, H Clark, TW Knight, and A Cavanagh

Proceedings of the New Zealand Society of Animal Production, Volume 66, Napier, 172-175, 2006