Hegarty, Roger

Herd, RM

Goopy, John Patrick

McCorkell, B

Arthur, PF

2005

A 70-day residual feed intake (RFI) test on a barley-based feedlot ration was conducted, over which daily feed intake (FI) and weekly liveweight of 91 Angus steers were recorded. Rate of enteric methane production (MPR) was measured in a series of 5×2-day consecutive measurement periods using a marker-based method with the marker gas (SF₆) released from an intraruminal permeation device. Data for 76 steers with 3 or more valid 2-day methane collections were analysed. The 43 low. RFI (high efficiency) line steers (progeny of 9 sires) and the 24 high-RFI (low efficiency) line steers (5 sires) represented approximately 2.4 generations of divergent selection for postweaning RFI. An additional nine intermediate unselected line steers were included. MPR (g/day) was highly, significantly related to daily FI (kg/day) over the 10-day gas-collection period: MPR=13.0±3.0 (se) × FI+34.9, although FI (P<0.0001) explained only 20% of the variance in MPR. From this relationship MPR over the 10-week RFI test was predicted. MPR predicted for the low-RFI line steers was not significantly lower than for the high-RFI line steers (187±4 v 199±4 g/day; P>0.05). Regression analyses showed MPR to be significantly related to genetic variation in RFI (P<0.05), such that a 1 kg/day reduction in estimated breeding value for RFI would be accompanied by a 13.0±5.1 g/day, or 7%, reduction in methane production. This result supports predictions that reduction in methane emissions should accompany the reduction in FI following from selection for lower RFI.

Proceedings of the Association for the Advancement of Animal Breeding and Genetics, v.16, p. 334-337

064309234X

0643092331

1328-3227

https://hdl.handle.net/1959.11/5285

en

Selection for residual feed intake can change methane production by feedlot steers

Conference Publication

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