Abstract

Twinning Hereford x Friesian beef cows were run in farmlets with breeding ewes at Whatawhata Research Centre. The additional inputs and outputs of twinning cows were compared with those of single calving treatments. This was carried out in a farm systems environment so that the feed-back mechanisms inherent in biological systems could operate. Typically, the twinning beef cows lost 15% of their foetuses during pregnancy and had (in the most recent year) a calf survival rate of 80%. Comparable figures for single calving cows were 5 and 95% respectively. Twin calves weighed 200 kg at weaning compared to 240 kg for singles. The twin cow farmlets required 250 kg extra DM/cow and 5.7 extra hours of labour/cow at calving. The sheep were not measurably affected by cow treatment. Gross margin analyses using these and other trial data indicated that twinning cows were $44/cow less profitable than single cows. Further analyses showed however, that the twinning cow system would breakeven with the singles if any one of the following changes were possible, (1) twin calf wean weight 220kg, (2) twin calf survival 89%, (3) twin foetal loss 5%, (4) labour differences dropped from 5.5 (above) to 2.1 hours/cow. When all the breakeven values were assumed to have occurred at the same time, twin cows were $120/cow more profitable than single cows. This is the money available to pay for extra risk and the extra cost of getting a cow twin pregnant (at day 60) compared to single pregnant.

DC, Smeaton, and JB Clayton

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 245-247, 1998