Maternal productivity of Angus cows divergently selected for post-weaning residual feed intake

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doi:10.1071/EA05052

Maternal productivity of Angus cows divergently selected for post-weaning residual feed intake

P. F. Arthur ^A ^F ^G, R. M. Herd ^B ^F, J. F. Wilkins ^C ^F, J. A. Archer ^D ^E ^F

^A NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Camden, NSW 2570, Australia.
^B NSW Department of Primary Industries, Beef Industry Centre, Armidale, NSW 2351, Australia.
^C NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650, Australia.
^D NSW Department of Primary Industries, Agricultural Research Centre, Trangie, NSW 2823, Australia.
^E Present address: AgResearch Ltd, Invermay Agricultural Centre, Mosgiel, New Zealand.
^F Cooperative Research Centre for Cattle and Beef Quality, University of New England, Armidale, NSW 2351, Australia.
^G Corresponding author. Email: paul.arthur@dpi.nsw.gov.au





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Australian Journal of Experimental Agriculture 45(8) 985–993 http://dx.doi.org/10.1071/EA05052
Submitted: 12 February 2005 Accepted: 18 May 2005 Published online: 26 August 2005

Abstract

Data on 185 Angus cows were used to study the effect of divergent selection for residual feed intake on maternal productivity across 3 mating seasons, starting from 2000. The cows were the result of 1 to 2.5 generations of selection (mean of 1.5), and differed in estimated breeding value for residual feed intake by 0.8 kg/day. In general, cows lost subcutaneous fat (measured 2 times a year) during the period when they were nursing calves, and gained fat thereafter. No significant selection line differences in fatness were observed except for those measured at the start of the 2000 (10.8 ± 0.4 v. 9.3 ± 0.4 mm), 2001 (11.3 ± 0.4 v. 9.8 ± 0.4 mm) and 2002 (7.0 ± 0.5 v. 5.7 ± 0.5 mm) mating seasons, where high residual feed intake cows had significantly (P<0.05) higher rib fat depths. No significant selection line differences in weight (measured 4 times a year) were observed. However, the cows either maintained or lost weight during the calf nursing period, and gained weight thereafter, with mean weights ranging from 450 to 658 kg. There were no significant selection line differences in pregnancy (mean 90.4%), calving (mean 88.7%) and weaning (mean of 80.8%) rates, milk yield (mean 7.7 kg/day) and weight of calf weaned per cow exposed to bull (mean 195 kg). The study indicates that after 1.5 generations of divergent selection for residual feed intake there are no significant selection line differences for maternal productivity traits.