PERFORMANCE OF HAIR BREEDS AND PROLIFIC WOOL BREEDS OF SHEEP IN SOUTHERN ILLINOIS - LAMB PRODUCTION OF F1 EWE LAMBS

The effects of year, sex of lamb, breed of dam, and breed of sire were estimated for age at puberty, breeding to lambing interval, breeding weight, ovulation rate, and ewe productivity (weight of lamb weaned pe r ewe exposed) and its component traits in F1 ewe lambs produced from Suffolk and Targhee ewes mated to rams of three wool breeds (Finnsheep , Combo-6, and Booroola Merino) and two hair breeds (St. Croix and Bar bados). Ewe lambs were pasture-mated to Dorset rams when they were 8 t o 10 mo of age. A total of 334 Fl ewe lambs, born in the late winters of 1986 through 1989, were exposed. Year of birth was an important sou rce of variation for age at puberty (P < .05), breeding weight (P < .0 1), fertility (P < .05), prolificacy (P < .10), lamb survival (P < .10 ), lamb weaning weight (P < .05), and ewe productivity (P < .01). Ram lambs born to the F1 ewe lambs had lower (P < .10) survival rates to w eaning but were heavier (P < .01) at weaning than contemporary ewe lam bs. The F1 ewe lambs from Suffolk dams reached puberty earlier (P < .0 1), were heavier (P < .01) at breeding, and had higher (P < .01) ovula tion rates and greater (P < .01) prolificacy than ewe lambs from Targh ee dams. The Fl ewe lambs sired by Finnsheep rams reached puberty earl ier (P < .10), F1 ewe lambs sired by Booroola Merino and Barbados rams were lighter (P < .01) at breeding, and ewe lambs from Booroola Merin o sires had higher (P < .01) ovulation rates and greater (P < .01) pro lificacy than ewe lambs sired by rams of other breeds. The F1 ewe lamb s sired by rams of the hair breeds had lower prolificacy (-.12 lambs; P < .10) but greater fertility (+13.6%; P < .01) and ewe productivity (+1.8 kg; P < .10) than F1 ewe lambs sired by rams of the wool breeds.