Abstract

A model quantifying outputs of carcass from pasture inputs was used to study factors affecting biological efficiency (BE) of finishing beef from 6 months to slaughter. Two factors which determined biological efficiency (BE, kg carcass gain/ha/yr) on pasture were pasture utilisation and animal conversion efficiency. Effects of stocking rate, length of finishing period (1 v 2 years), mature size and maintenance efficiency of beasts on BE and its components were studied. Stocking rate was the major factor affecting utilisation rate however more lighter (eg. 12% more 750 kg than 900 kg mature sized) cattle need to be run to achieve equivalent pasture utilisation. Nine percent less cattle can be run in a 2 year system. Average conversion efficiency was 40% lower from finishing at 2 years than 1 year. An increase in mature size from 750 to 900 kg increased animal conversion by 14%. A 20% decrease in maintenance requirements increased animal conversion by 10%. Constraints to produce specified carcass weights further favoured BE with high mature weight beasts, particularly at intermediate carcass weights (250 kg). Breeding cattle for high mature size appears the best way of improving the cattle available for finishing.

JN, Clarke, and AL Rae

Proceedings of the New Zealand Society of Animal Production, Volume 51, , 401-404, 1991