Dorper fertility ideal for lamb production

Dorpers are a South African creation, a cross between the Dorset and a Persian sheep. They are highly fertile, and the rams don't experience the fertility down-time typical of other breeds from October to December.

Waipukurau breeder Robin Hilson first encountered Dorpers in South Africa and, though he recognised they were a hardy breed, he has been surprised with just how well they have stood up to the sparse feed conditions typical on the East Coast. "Its feed required for maintenance per kilo live weight is very low compared to other breeds. "The survivability has just got to be seen to be believed."

Peter Kettle said their losses from scanning to weaning had not exceeded 10% since they'd had the Dorpers. Losses this year with the difficult autumn/winter were 8%. "The physiology, I'm quite convinced, is different to other sheep," Peter said.

Dorpers shed their wool and require only 'tidy-up' shearing every couple of years or so. He believes the energy they save by not producing wool stands them in good stead at times of stress, like droughts, and allows them to be more feed efficient. "When they're born they have a little bit of guard hair on them. They're tough, they just get up and go. "They've got a very thick skin, it's got this real insulating quality."

Though they shed, Robin said it was very rare to see any wool in the paddock. "If you take a mob through the yards you'll see a little bit of hair or kemp as if the sheep have been crutched, like a deer shed, or goats.
"I just can't believe the number of lambs I haven't lost. Of all the sheep we've had over the generations on this farm, they have the minimal amount of losses.

Peter said the maternal qualities of Dorpers were also impressive, a feature which impressed Robin when he looked at Dorpers in Australia. "When the drought pressure really came on, they got into lamb every time they showed them a ram, and they kept their condition. They came out tops in absolutely everything on the maternal side."

Meat processors have reported an average extra 8% red meat yield from the Dorpers.

Massey Study
On a Manawatu farmlet a Meat & Wool funded Massey project found that artificially inducing oestrus and ovulation in high fertility ewes, along with good pasture growth, resulted in successful year-round mating.

The project was led by Professor Steve Morris, who said feed demand for the year was only slightly higher. "It is just spread more evenly."

Under the trial system, a flock was divided into three mobs and put on rotation lambing. Every 73 days, a ram was put to a mob and, as the cycle continued, lambs were born every 73 days, weaned 73 days later when the ewes were again put to the ram. An increase in production was achieved.

"Being able to produce lambs all year-round also paves the way for special supply and branding arrangements with processors," Prof Morris said. Although lambing year-round increased scanning percentages, he said, it may result in higher lamb losses. Almost 70% of the 133 high-fertility ewes in the accelerated system were impregnated at each mating, which can equate to more profitability than the almost 100% in-lamb rate achieved through once-a-year lambing.

-RURAL CENTRAL DISTRICTS • October 2007

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