PERFORMANCE OF HAIR BREEDS AND PROLIFIC WOOL BREEDS OF SHEEP IN SOUTHERN ILLINOIS - LAMB PRODUCTION OF F1 ADULT EWES

Two- and three-year-old F-1 crossbred ewes produced from Suffolk and T arghee dams and sires of the prolific wool breeds of Finnsheep, Combo- 6, and Booroola Merino and the hair breeds of St. Croix and Barbados w ere pasture-mated to Dorset rams over a 4-yr period at the Dixon Sprin gs Agricultural Center in southern illinois. Booroola Merino sires wer e homozygous for the Fec(B) allele for high number of ovulations. The effects of age of ewe, sex of lamb (where appropriate), breed of dam, and breed of sire on condition score, breeding weight, ovulation rate, breeding to lambing interval, fertility, prolificacy, lamb survival, weaning weight, and ewe productivity were estimated. All traits were a nalyzed using mixed-model methodology. Crossbred ewes from Suffolk dam s had a higher (P < .01) condition score, heavier (P < .01) breeding w eight, higher (P < .01) ovulation rate, shorter (P < .01) breeding to lambing interval, greater (P < .01) prolificacy, heavier (P < .01) lam bs at weaning, and greater (P < .05) ewe productivity than crossbred e wes from Targhee dams. Ewes from hair-breed sires had lighter (P < .01 ) breeding weight, lower (P < .05) ovulation rate, shorter (P < .05) b reeding to lambing interval, higher (P < .05) fertility, higher (P < . 05) lamb survival, lower (P < .10) lamb weaning weight, and higher (P < .05) ewe productivity than ewes sired by the prolific wool-breed ram s. The breed of sire x breed of dam interaction was a significant sour ce of variation for breeding weight, fertility, lamb survival, and ewe productivity. The results indicated a definite advantage of hair-cros s ewes over wool-cross ewes for lamb production in southern Illinois. Even though the Booroola Merino-sired ewes were heterozygous for the F ec(B) allele, their apparent poor adaptability to the environment resu lted in them achieving the lowest lamb production of any of the sire b reed groups.