Variation in cattle liveweights at marketing

Abstract

The liveweights of Friesian bulls farmed on 3 farmlets during 4 years were analysed to find how the variation in liveweight increased through time, and to review some possible farm management strategies for limiting the increase in this variation. There were 59 bulls in 1986, 66 bulls in 1987, 59 bulls in 1988 and 61 bulls in 1989. The variation in animal liveweights within a mob increased linearly through time. The small variance in the slopes of the estimates indicated that the increase in liveweight variation through time could be predicted very accurately. The rate of increase of variation through time differed in only one year (1987; P< 0.01). Variation in animal liveweight between farmlets was constant through time, and not associated with the rate of increase of within mob liveweight variation. It was shown that the ranking of animals within the frequency distribution of animal liveweight changed through time. Thus the current liveweight rank of an animal was no guide to liveweight rank 5 or 6 months in the future. This suggests that minimising the increase in liveweight variation through time by dividing a mob of cattle is not feasible. The importance of control of variation in agricultural products for the operation of on-farm quality assurance schemes is discussed, and avenues for exploration of management tactics designed to minimise variation in the production of animals for slaughter suggested. Keywords: bulls, liveweight, marketing, on-farm - quality assurance