Abstract

The effect of year of birth and nutritional treatment on liveweight variance in mobs of Angus steers from birth until approximately 30 months-of-age is examined. Significant (P<0.01) differences in liveweight variance at 30 months-of-age were recorded between years. The environment of the calves over the first 20 days of life appeared to affect the development of mob variance, steers which experienced early life on a sawdust pad showing higher variance at 30 months-of-age in liveweight and carcass weight. Restricted nutrition during the first winter of the steer`s life was associated with a significantly (P<0.05) higher variance in 30 month liveweight (standard deviation 24.0 v 37.8kg). Within mob, lower rates of liveweight change were associated with an increase in liveweight variance (r = -0.72). A mathematical model was used to assess the effects of controlled mating strategies on mob variance. Minor improvements were possible. The implications of controlling mob variance for farm quality assurance management is discussed.

AB, Pleasants, WH McMillan, and RA Barton

Proceedings of the New Zealand Society of Animal Production, Volume 59, , 173-176, 1999