Poll Dorsets perform well in trials

Press, 8 November 1978, Page 28

Poll Dorsets perform well in trials

Lean carcases; fast growth

The Poll Dorset sheep, and the Dorset Horn before it, has been used almost exclusively as a fat lamb sire, but trials at the Templeton Research Station run by the Ministry of Agriculture point to it having a worth while place as a commercial breeding ewe. Two traits which stand out above the standard ewe breeds Are its longer breeding season — four to si> weeks greater than the standard ewe breeds — ant its prolific milking ability. Since 1973, the Templeton station has used all possible crosses involving the Corriedale Romney and Dorset breeds. At present it has a flock of 750 crossbred ewes, which are mated to three sire breeds. Research is being focused on ewe breeds and lambs for export prodhetion. A five-year average, 1972 ta 1976, credited the Dorset ewe with a lambing performance of 1.53 per head, while the Corriedale averaged 1.40 and the Romney 1.33. Weaning figures credited the Romney with an average over four seasons of 1.09, the Corriedale 1.28 and the Dorset 1.23. These figures were based on ewes lambed rather than ewes mated. Dorset and Dorset-cross lambs have achieved remarkably good growth rates. Using the Romney as a base 100, the Dorset figure was 140, and the Corriedale 120. Not surprisingly, the Dorset had a low figure for wool, 66. as against 111 for the Corriedale. But the Dorset and Dor-set-cross ewes are hardier. Mr Ken Geenty, an animal scientist with the Ministry at Templeton, has found that under adverse conditions, they lose weight much less readily than the Corriedale. So this might suggest that they could be run at higher stocking rates. Compared with other

breeds, Dorset and Dorset cross lambs have lowe fat levels and leaner cai cases. This is an impor ant aspect when related I export grading. At present the ma imum depth of fat ov ■ the twelfth rib for gradir prime is 15mm. The lorn term aim is to reduce th to 10mm. If this minimui was imposed today, V Geenty estimates that f per cent of New Zealar lambs would grade ove fat. Weaning trials have fv nished worth-while inf< mation on ways of rede ing fat legels. Three groups weaned r spectively at five week nine weeks and 15 week' were slaughtered at 1 weeks, returning car'cas weights of 13.28k.i 13.67 kg, and 14.36 kg. Depth of fat (over th< twelfth rib), was 7.0 for the lambs weaned at five weeks, 8.2 for those weaned at nine weeks, and 9.4 for those weaned or the point of slaughter al 15 weeks. Carcase fat percentage' were 14.1, 15.1 and 19. for the respective groups. Those weaned at 1; weeks graded best, with a maximum 100 per cent.. Ninety-two per cent of those weaned at nine weeks graded prime, while the figure for those weaned at, five weeks was 69 Mr Geenty pointed out that because of the good price for Y grade lambs on last year’s export schedule, there was little difference between those weaned at nine weeks and those weaned at 15 weeks. Mr Geenty considers there are good reasons for weaning in good time, providing the lambs are in the 10 to 12kg weight range at the age of five weeks. Weaning at 10 to 12 weeks, he said, was ‘‘too late.”