Interest In More Lambs

Press, Volume CVI, Issue 31362, 6 May 1967, Page 10

Interest In More Lambs

The recent disastrous drought in New South Wales and Queensland had made graziers more conscious of the need to improve lambing percentages, the assistant manager of the Sydney branch of Dalgety and New Zealand Loan, Ltd., Mr M. F. Bretnall, said recently.

About 20 per cent of Australia’s lambs were lost at birth, he said. “Some landholders, who have not paid enough attention to lambing percentages in the past, are making every effort to replace depleted flocks by careful selection of ewes to increase multiple births,” Mr Bretnall said. “They realise that if they halve their lambing losses, they will double the rate of flock increase.

“Many graziers are joining ewes twice within 18 months in an accelerated programme to lift sheep numbers.”

Quickest Way

The officer-in-charge of sheep breeding research in the division of animal genetics of the Commonwealth Scientific and Industrail Research Organisation, Miss Helen Newton Turner, said the quickest way to rebuild breeding flocks was to retain ewes beyond the normal culling age of five to six years.

Trials at Gilruth Plains, south western Queensland, showed that reproductive performance of flocks increased with the age of the oldest ewes up to nine years, she said. Longevity of sheep varied from region to region

as did the survival rate of lambs.

Tests indicated that the proportion of ewes failing to lamb would fall as the casting age rose up to five years and would change little thereafter.

The proportion of ewes bearing twins would rise with the casting age up to 10 years but would rise only slightly after Inclusion of ewes older than seven years. Wool Retention of ewes and wethers was an important economic decision for graziers as the wool cut per head in breeding flocks commonly fell after two to three years of age. The extent of this decline depended upon the locality and possibly the strain of Merino sheep concerned. However, the additional lambs could well compensate for the loss of wool. “The age of ewes and reproduction should be examined in all areas,” Miss Turner added.

In the United States, scientists at Purdue University, Lafayette, Indiana, said landholders should be urged to wean lambs in 60 to 70 days

and produce three lamb crops every two years. This would require better management as lambs weaned at 60 to 70 days would need more adequate nutrition, but early weaning should not materially affect their growth rate if modern balanced rations were supplied. Ewes producing a lamb crop every eight months, the scientists said, would not become too fat and would conceive more quickly. They also would have less difficulty at lambing time. A ewe’s gestation period varied from 140 to 150 days, or roughly five months, and the productive life of the average ewe was six years, extending from about 18 months to seven years and a half. Increase At present, a ewe would normally produce about six crops of lambs. If ewes were joined to produce nine crops of lambs, this would represent an increase of 50 per cent in productivity and would be achieved with very little Increase in feed costs, labour or equipment, the scientists added.