Assessing Wiltshire Horn-Merino crosses. 3. The 50% Wiltshire Horn as a prime lamb producer

Abstract

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.

Relative performance and efficiency of five Merino and Merino-type dam lines in a terminal crossbreeding system with Dormer or Suffolk sires

“…Differences between dam lines could mostly be attributed to the comparison of purebred Merino lines with the dual-purpose lines (Table 3). Rathie & Teasdale (1994) also found that purebred Merinos were outperformed by dual-purpose ewes. The lower dressing percentage of lambs from purebred Merino lines could be due to their generally thinner fat cover and more wool on the skins (Kirton et al, 1995).…”