Wiltshire Horn-Merino (WH-M) crosses of 1/2, 5/8 and 3/4 Merino content were compared over 10 years for wool shedding, blowfly strike frequency and wool production traits. Merinos and 1/2 Merino WH-M were compared over 4 years. For wool production traits, 1/2 and 5/8 Merino WH-M ewes were compared to Border Leicester-Merino (BL-M) ewes over 2 years. Shedding increased with age for all WH-M genotypes, with 3/4 Merinos showing less shedding than 1/2 Merinos at all ages. At 1 and 2 years of age, 5/8 Merinos were intermediate between the other 2 WH-M genotypes, but at later ages they were similar to 1/2 Merinos. All genotypes showed less shedding at the belly site than the head, neck and breech as lambs, but not at older ages. Phenotypic correlations between sites on the same sheep were high, averaging 0.85. Repeatability estimates for each site ranged from 0.26 to 0.45. Shedding increased most with age in the 1/2 Merinos, and least in the 3/4 Merinos. Little or no shoulder and back wool was shed by most sheep. All 1/2 and 5/8 Merinos and most 3/4 Merinos had bare legs and points. Blowfly strike incidence was far higher in Merinos than 1/2 Merinos, in all years. Among WH-M, blowfly strike incidence increased as Merino content increased, in all years. All WH-M were far inferior to both Merinos and BL-M in total greasy wool weight and all its components, and also in clean fleece weight, with their level of inferiority increasing as their Merino content declined. Wool fibre diameter for all WH-M was coarser than for Merinos, but was a little finer than for BL-M. Fibre diameter increased in the WH-M as their Merino content declined. All WH-M had lower wool yields than the Merinos or BL-M. In some years the 314 Merinos had lower wool yields than the 1/2 and 5/8 Merinos, which were similar in all years. Shedding caused numerous genotype x age interactions in wool weight and its components, as Merinos and BL-M did not shed, and with the WH-M shedding increased most with age in the 1/2 Merinos, and least in the 3/4 Merinos. Due to preferential shedding from the belly and other low-value areas, the WH-M inferiority in total wool weight was less severe for fleece weight. Winter shearing succeeded in harvesting some wool from WH-M that would be shed before a summer shearing, but not enough to alter rankings among genotypes. All WH-M genotypes have wool too coarse, and not enough of it, to compete as a wool sheep with the Merino at current wool prices under usual Australian pastoral conditions. In areas where mustering is difficult or blowfly strike unusually severe, WH-M genotypes may find a niche.

Wiltshire Horn-Merino (WH-M) and Border Leicester-Merino (BL-M) ewes, both with 50% Merino ancestry, were mated in late spring to lamb in 1985 and 1986 to either Dorset Horn (DH) or WH-M rams. Lambs from WH-M sires grew more slowly than lambs from DH sires, by 2 to 13% depending on dam breed and age of lamb. Lambs from WH-M dams grew 3 4 % slower than lambs from BL-M dams in 1985, a year of good pasture and with only DH rams used. In the following year, they grew at a similar rate from birth to weaning if from DH sires, but 11% more slowly if by WH-M sires. From weaning to turnoff, the ranking was reversed, with lambs from WH-M dams growing 11% faster, and sire breed not significant. When mated to DH rams, both the WH-M and BL-M ewes produced lambs with similar dressing percentages and fat depths over the 12th rib. Lambs sired by WH-M rams were leaner than those sired by DH rams, particularly for single-born lambs. The WH-M ewes tended to have a higher percentage of lambs marked per ewe joined than the BL-M ewes, but the advantage was not statistically significant. The difference was mainly due to fewer barren ewes, but the WH-M ewes also showed slightly higher prolificacy. The WH-M ewe shows good fertility and prolificacy, and when mated to a DH ram gives lambs with growth and carcase characteristics very similar to a BL-M identically mated. Mated to a WH-M ram, it gives slower growth but leaner carcases capable of being efficiently grown to heavier liveweights than conventional Australian 3-breed crosses.

Wiltshire Horn-Merino (WH-M) crosses of 1/2, 5/8 and 31/4 Merino content were compared for various reproductive traits over an 8 year period. For 3 years pure Merinos were also included in the comparison. Merino ewes were of lower fertility and fecundity than the 1/2 Merino WH-M ewes. For example, numbers of ewes lambed per 2-year-old ewes joined were 2.6-15% lower for Merinos. For fecundity in 3-year-olds, litter sizes for Merino ewes averaged 0.33 lambs fewer than for 1/2 Merino WH-M. Among the WH-M ewes, fertility was uniformly high for all genotypes. Fecundity was considerably higher for 1/2 Merinos than for the 5/8 and 3/4 Merinos. There was no evidence of a difference in fertility or fecundity between F1 and later-generation 1/2 Merinos, and hence no evidence of heterosis. In 2 severe drought years the lambing percentages decreased most in the more productive ewes (1/2 Merinos and older ewes). Genotypes and age groups were more similar than in non-drought years, although a significant effect of genotype was still present in all years.