Genetic and phenotypic correlations and heritability estimates of side, britch, and core diameters; side and britch CV; side and britch diameter difference; and clean fleece weight were investigated using 385 western white-faced ewes produced by 50 sires and maintained at two locations on a selection study. Data were analyzed using analysis of variance procedures, and effects in the final model included breed of sire-selection line combination, sire within breed-selection line, and location. Heritabilities were estimated by paternal half-sib analysis. Sires within breed-selection line represented a significant source of variation for all traits studied. Location had a significant effect on side diameter, side and britch diameter difference, and clean fleece weight. Age of ewe only affected clean fleece weight. Phenotypic and genetic correlations among side, britch, and core diameter measures were high and positive. Phenotypic correlations ranged from .68 to .75 and genetic correlations ranged from .74 to .89. The genetic correlations between side and britch diameter difference and side diameter or core diameter were small (-.16 and .28, respectively). However, there was a stronger genetic correlation between side and britch diameter difference and britch diameter (.55). Heritability of the difference between side and britch diameter was high (.46 +/- .16) and similar to heritability estimates reported for other wool traits. Results of this study indicate that relatively rapid genetic progress through selection for fiber diameter should be possible. In addition, increased uniformity in fiber diameter should be possible through selection for either side and britch diameter difference or side or britch CV.

Production data from 681 yearling ewes were evaluated for the effect of ewe breed and management system on fertility, prolificacy, lamb birth weight, lamb survival, lamb weaning weight, ewe fleece weight, and total lamb weight weaned per ewe exposed. Two hundred seven straightbred Targhee (T) and 474 1/4 Finn-1/4 Dorset-1/2 Targhee (FDT) crossbred ewes managed in a range or farm flock system were included in this study. Ewes were born in 1984 through 1987 and lambed the first time as 2-yr-olds. The basic model included main effects of ewe breed and management system. Lamb sex was added to the model for birth and weaning weight analysis. The FDT ewes had higher (P < .05) fertility (95.3 vs 91.3%) and (P < .01) prolificacy (1.93 vs 1.45 lambs) than the T ewes. Targhee ewes had heavier (P < .01) lambs at birth (5.2 vs 4.0 kg) and weaning (26.1 vs 23.4 kg, P < .01) and produced more (P < .01) wool (3.8 vs 3.2 kg). Lamb survival was not different (P > .10) between the breeds or management systems. Although FDT lambs were lighter at weaning, FDT ewes weaned 5.8 kg more (P < .01) total lamb weight per ewe exposed than did the T ewes (34.7 vs 28.9 kg), because FDT weaned more (P < .01) lambs per ewe exposed (1.46 vs 1.09 lambs). Farm flock ewes were more prolific (1.73 vs 1.64 lambs, P < .05) and had heavier lamb birth weight (4.8 vs 4.4 kg, P < .01) than range flock ewes.(ABSTRACT TRUNCATED AT 250 WORDS)