Development of the Polypay breed of sheep

TitleDevelopment of the Polypay breed of sheep
Publication TypeBook Chapter
Year of Publication1983
AuthorsHulet CV, Ercanbrack S.K., Knight A.D.
EditorBaker F.H.
Book TitleSheep and Goat Handbook
PublisherWinrock International, Westview Press
CityBoulder, CO
KeywordsComposite Breed Development, Polypay, Reproductive Performance, Selection

Development of the Polypay breed was undertaken to combine into a composite breed the potential for greatly increased reproductive capacity along with desirable growth rate and carcass quality. Four breeds were selected for the foundation of the new breed-the Rambouillet and the Targhee for hardiness, large body size, long breeding season, herding instinct and fleece characteristics; the Dorset for carcass quality, milking ability and long breeding season and the Finnsheep for early puberty, early postpartum fertility and high lambing rate. Dorset x Targhee and Finnsheep x Rambouillet matings were first made in 1968, and reciprocal Dorset-Targhee x Finn-Rambouillet matings were initiated in 1969. Beginning in 1970, the respective two-breed crosses and the four-breed cross (Polypay) were each mated inter se and selected, along with straight bred Rambouillets and Targhees, or lamb production when given two opportunities to lamb/year. Initial comparisons among straightbreds and inter se mated groups showed few important differences in meat-type body conformation, body condition or growth rate, but superior annual reproductive performance by Polypays. Fertility of Polypays at 1 yr of age was high and comparable to that of the Finn- Rambouillets. Response of Polypays to twice-a-year lambing was superior to responses of Rambouillets, Targhees, Dorset-Targhees or Finn-Rambouillets. The 1974 to 1975 annual production of young Polypays was about 13% more lambs weaned than from Finn-Rambouilets and 18% more weight of lamb weaned than from Dorset-Targhees, the best of the other groups for these traits. The current (1979 to 1981) reproductive performance of Polypay ewes selected for high once-a-year lambing rate under typical range management conditions is very competitive with that of 89 Finn cross- breds. Annual production of mature Polypays on the twice-a-year lambing schedule was 1.78 lambs weaned and 58.6 kg of lamb weaned/ewe put into fall breeding.