Genetic correlations between wool traits and carcass traits in Merino sheep1

Abstract

Genetic correlations between 29 wool production and quality traits and 14 whole carcass measures and carcass component traits were estimated from the Information Nucleus of 8 flocks managed across a range of Australian sheep production environments and genetically linked. Wool data were from over 5,000 Merino progeny born over 5 yr, whereas carcass data were from over 1,200 wether progeny of over 176 sires, slaughtered at about 21 kg carcass weight, on average. Wool traits included yearling and adult records for wool weight, fiber diameter, fiber diameter variation, staple strength, scoured color, and visual scores for breech and body wrinkle. Whole carcass measures included HCW, dressing percentage (DP), and various measures of fat depth and eye muscle dimensions. Carcass components were obtained by dissection, and lean meat yield (LMY) was predicted. Heritability estimates for whole carcass measures ranged from 0.12 ± 0.08 to 0.35 ± 0.10 and ranged from 0.17 ± 0.10 to 0.46 ± 0.10 for carcass dissection traits, with no evidence of important genotype × environment interactions. Genetic correlations indicated that selection for increased clean wool weight will result in reduced carcass fat (-0.17 to -0.34) and DP (-0.48 ± 0.15), with little effect on carcass muscle. Selection for lower fiber diameter will reduce HCW (-0.48 ± 0.15) as well as carcass fat (0.14 to 0.27) and muscle (0.21 to 0.50). There were high genetic correlations between live animal measures of fat and muscle depth and the carcass traits (generally greater than 0.5 in size). Selection to increase HCW (and DP) will result in sheep with fewer wrinkles on the body (-0.57 ± 0.10) and barer breeches (-0.74 ± 0.12, favorable), with minor deterioration in scoured wool color (reduced brightness and increased yellowness). Selection for reduced fat will also result in sheep with fewer body wrinkles (-0.42 to -0.79). Increasing LMY in Merinos through selection would result in a large reduction in carcass fat and DP (-0.66 to -0.84), with a smaller increase in carcass muscle and some increase in wool weight and wrinkles. Although no major antagonisms are apparent between the wool and carcass traits, developing selection indexes for dual-purpose wool and meat breeding objectives will require accurate estimates of genetic parameters to ensure that unfavorable relationships are suitably considered. The findings will aid development of dual-purpose wool and meat breeding objectives.

Expression and tissue distribution analysis of vimentin and transthyretin proteins associated with coat colors in sheep (Ovis aries)

“…Under the combined influence of gene regulation and environment, livestock exhibits the final coat color. Wool color is an important production trait of sheep [13,14]. The coat color of sheep is mainly white, black, brown, and patchy variegated [15].…”

SNP associations and genetic-parameter estimation for nose and hoof pigmentation in Corriedale sheep

“…The lambs were slaughtered at lighter weights (20.64 kg) than in similar trials with other meat breeds (21.6-23.1 kg;Mortimer et al 2010Mortimer et al , 2014 and Merino lambs (21.1 kg; Mortimer et al 2017bMortimer et al , 2018. The EMA of Corriedale lambs was within the range of means reported in Merinos (11.6-13.1 mm;Mortimer et al 2010Mortimer et al , 2017bMortimer et al , 2018. The GRFat depth in Corriedales (7.46 mm) was lower than GRFat of Merinos (10.7 mm; Mortimer et al 2018) and Merino × lambs (21.6 mm; Mortimer et al 2010).…”

Abstracts from the Proceedings of the 33rd Biennial Conference of the Australian Association of Animal Sciences

“…Selection for the breeding objective trait of lean meat yield percentage in lamb is currently achieved using correlated live animal measures (e.g. weights and ultrasound scans) and carcase measures (hot carcase weight, Csite fat depth and GR tissue depth) (Mortimer et al 2017). The collection of the carcase composition traits is currently a labour intensive and expensive process.…”