Coopworths are renowned for their high productivity in many varied farming environments from dry plains to hard hill. Weaning percentages and wool clips are consistently higher than other breeds. Coopworth ewes are good milkers and a high percentage of lambs can be drafted at weaning if season or policy dictates.
Coopworths are bred for easy care characteristics: clean heads and points means they do not require eye-wigging and they move well. Ewes require minimum shepherding at lambing: difficult births are of low incidence, and ewes have very good mothering instinct. Thus the costs of production are reduced compared to many other breeds.
"Coopworth Society regulations have been formulated to guarantee genetic progress for economically important characteristics"
Key points in the regulations are:
All registered flocks must be performance recorded
Registration is performance based, not pedigree based
Ewes can be screened into registered flocks if they perform outstandingly as hoggets and 2 tooths in commercial flocks. The Coopworth Society has an open flock book
Single entered rams must come from the highest ranking 15% of the flock for performance
Ewes must rear 3 lambs in the first two lambings to retain registered status
Ewes requiring assistance at lambing are deregistered
Coopworth breeders have not rested on their Society's regulations. The use of sire referencing through AI and ram circling has seen dramatics lifts on production. They are to the fore in breeding for traits like:
FE testing to ensure flocks never have to worry about the huge economic loss this disease can cause
Breeding worm tolerant sheep to reduce the need for drench
Eye muscle scanning to produce the best carcass for the market
Wool measurements to ensure flocks are producing the best clean wool for the market
Ewes rearing their own weight in lambs
The Coopworth breed had its origins in the immediate post-World War II years when scientists considered that every endeavour should be made to improve lambing percentages, which they considered were much too low. Research was initiated to improve fertility levels through nutrition, reproduction, disease control and breeding.
Lincoln College chose to examine crossbreeding to replace some of the traditional straight-bred Romneys and Corriedales with first-cross ewes. The Border Leicester was chosen as the crossing sire, for despite some faults, it was known to have the highest lambing percentage of all breeds available in New Zealand, had good mothering ability and milk production and white wool.
Photo of 1978 North Island Sheep Breeders Sale in Gore
Experiments begun in 1950 established that the F1 Border X Corriedale and Border X Romney produced 20-30% more lamb weaned than the straight-breds. These results were adopted and led to the now common use of Border cross ewes.
But there is a limit to the number of such ewes, given the need to have pure Border Leicester and Romney parent flocks. It was thought that if a pure-breeding interbred Border Romney could be produced having the characteristics of the first-cross the impact would be far greater.
The College, and two or three individual breeders, set about this task. Border Leicester sires and Romney ewes from a range of sources were carefully selected on the basis of production data available. They were crossed to form the foundation F1 stock and then interbred. An essential feature of the whole process was performance recording, with selection (and culling) on the basis of measured performance - number of lambs born or weaned, adjusted weaning weight, fleece weight and quality and easy care. Continuous recording and analysis monitored progress during the interbreeding. To widen the range of environments used, F1 and F2 rams were distributed to first-cross breeders for assessment by them.
By the late 1960s farmers involved in interbreeding programmes believed that their stabilised interbred Border Romneys at the F3-F4 level were at least equal to the first-cross sheep and certainly superior in overall performance to the original Romneys used. This led in 1968 to the formation of a Breed Society, which became known as Coopworth.