Genetic parameters for wool production and quality traits in South Australian Merinos of the Collinsville family group

Abstract

Heritabilities and phenotypic and genetic correlations for fleece traits were estimated from a data set comprising 805 male and female progeny of 44 sires of the Collinsville family group. Characteristics included in the study were greasy and clean fleece weight, yield, mean, standard deviation and coefficient of variation of fibre diameter, resistance to compression, scoured and greasy wool colour (expressed as yellowness, lightness and yellowness index), wax content, suint content, and subjectively assessed scores for greasy colour, character, handle, quality number, condition, staple formation, tip formation and density. Heritabilities of greasy and clean fleece weight, yield, mean fibre diameter and subjectively assessed fleece scores were in broad agreement with estimates from other Merino strains, but the genetic correlations of mean fibre diameter and associated characters (handle, quality number) with clean fleece weight were lower than previous estimates. Heritabilities for scoured yellowness of wool, resistance to compression and coefficient of variation of fibre diameter, which are potential additional measurements for the specification of wool in sale lots, were 0.42 (�. 0.14), 0.57 (� 0.15) and 0.47 ( � 0.15) respectively. Estimated heritabilities of wax and suint content were 0.24 (�0.11) and 0.44 ( � 0.14). Although the phenotypic correlations between measures of greasy wool colour and the corresponding measures of scoured wool colour were low (less than 0.3), the genetic correlations were moderate to high (0.4-0.9). Thus selection on the basis of greasy wool colour should lead to genetic improvements in scoured colour. The genetic correlations of resistance to compression with clean fleece weight and fibre diameter were: 0.46 (�0.21) and 0.44 (� 0.20) respectively, but there were no other strong, unfavourable correlations.

Genetic parameters for wool traits, live weight, and ultrasound carcass traits in Merino sheep1

“…A heritability of 0.55 ± 0.16 for scoured wool brightness (yY) has also been reported (James et al, 1990). There is a similar range of estimates of heritability for greasy color measurements (James et al, 1990;Raadsma and Wilkinson, 1990).…”

Genetic parameters for wool traits, live weight, and ultrasound carcass traits in Merino sheep

“…These estimates of heritability for the wool production and wool quality traits are generally consistent with those reviewed by Safari et al (2005) and more recent reports from large Merino data sets (Asadi Fozi et al, 2005;Safari et al, 2007a;Swan et al, 2008Swan et al, , 2016Brown et al, 2010Brown et al, , 2013. The few reports of estimates for heritability of scoured wool yellowness color (Y-Z) in Merino sheep range from 0.25 for yearlings and 0.29 for adults (Smith and Purvis, 2009) to 0.42 ± 0.14 (James et al, 1990) and 0.45 ± 0.08 (Hebart and Brien, 2009), with estimates from Coopworth and Romney sheep being lower (0.13 ± 0.06; Bigham et al, 1983). A heritability of 0.55 ± 0.16 for scoured wool brightness (yY) has also been reported (James et al, 1990).…”

“…The few reports of estimates for heritability of scoured wool yellowness color (Y-Z) in Merino sheep range from 0.25 for yearlings and 0.29 for adults (Smith and Purvis, 2009) to 0.42 ± 0.14 (James et al, 1990) and 0.45 ± 0.08 (Hebart and Brien, 2009), with estimates from Coopworth and Romney sheep being lower (0.13 ± 0.06; Bigham et al, 1983). A heritability of 0.55 ± 0.16 for scoured wool brightness (yY) has also been reported (James et al, 1990). There is a similar range of estimates of heritability for greasy color measurements (James et al, 1990;Raadsma and Wilkinson, 1990).…”

Indirect selection criteria against clean wool colour in Corriedale sheep and their effects on wool production traits

“…Surprisingly, Barlow (1974) and Wuliji et al (1993) reported no significant differences in CWC in progeny of high fleece weight selected Peppin Merino and Romney ewes, respectively, and random control flocks. On the other hand, a negative genetic correlation between CFW and CWC found in Collinsville Merinos (James et al, 1990) indicated that CWC would improve under selection for higher CFW. The positive genetic correlation estimates between YPC and fleece weights found here also disagree with the findings of Wilkinson and Aitken (1985) who reported negative genetic correlations for YPC with GFW and CFW of -0.41 ± 0.35 and -0.71 ± 0.35, respectively.…”

“…Studies on the genetics of wool yellowing have found that the heritability of clean wool colour (CWC) -measured in Y-Z units -varies from 0.04 ± 0.07 in Romney sheep in New Zealand (Hawker et al, 1988) to 0.42 ± 0.14 for Collinsville Merinos in Australia (James et al, 1990). The variation between these heritability estimates might have been due to environmental variation caused by differences in weather conditions between the locations of these studies.…”