Genetic and phenotypic parameter estimates for selection to improve lamb carcass traits

Waldron, D. F.; Clarke, J. N.; Rae, A. L.; Kirton, A. H.; Bennett, G. L.

doi:10.1080/00288233.1992.10427506

Cited by 29 publications

(20 citation statements)

References 15 publications

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“…However, current findings were comparable to findings of Simm et al (2002), who reported values of 0.41 for UMD and 0.56 for UFD, and to results reported by Botkin et al (1969) (UFD: 0.51) and Waldron et al (1992) (UMD: 0.38). For the study reported by Botkin et al (1969) the animals were older (mean age of 193 days) and of a different breed than in the present study.…”

Section: Genetic Parameters For Ultrasound Measurementsupporting

confidence: 91%

Selection for lean weight based on ultrasound and CT in a meat line of sheep

Kvame¹,

Vangen

2007

Livestock Science

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Section: Genetic Parameters For Ultrasound Measurementsupporting

confidence: 91%

Selection for lean weight based on ultrasound and CT in a meat line of sheep

Kvame¹,

Vangen

2007

Livestock Science

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“…The estimates of genetic and phenotypic correlations between ultrasound traits and carcass traits are shown in Table 7. Genetic correlations between ultrasound measures of fat depth measured at the C site on live animals and the various carcass measures of fat depth were generally high (0.63 to 0.94), consistent with other reports where ultrasound fat depth was adjusted for live weight and measures of carcass fat depth were adjusted for carcass weight (Waldron et al, 1992;Greeff et al, 2008;Mortimer et al, 2010;Maximini et al, 2012;Brito et al, 2015;Einarsson et al, 2015). Genetic correlations between ultrasound EMD and carcass EMD and EMA were also high (0.82 to 0.99), although they were lower with carcass EMW (0.32 to 0.36), which confirms previous estimates (Greeff et al, 2008;Mortimer et al, 2010;Maximini et al, 2012).…”

Section: Ultrasound Traits With Carcass Measures Traitssupporting

confidence: 89%

“…Heritability estimates have been moderate to high from the relatively few studies that have estimated genetic variances for carcass dissection traits in sheep, with our results consistent with those earlier estimates. These earlier reports for heritability include 0.36 for WTLL and 0.37 for total lean (Waldron et al, 1992), 0.27 ± 0.06 for meat in 3 primal cuts (Kenney et al, 1995), 0.27 ± 0.11 for lean in the shoulder (Conington et al, 1998), 0.41 for WTLL and 0.24 to 0.31 for lean in various other cuts (Johnson et al, 2006), 0.46 for lean in the carcass (van Heelsum et al, 2006), 0.37 for lean in the loin (Jopson et al, 2009), and 0.32 ± 0.14 for WTLL and 0.24 ± 0.14 for WTTOP (Lorentzen and Vangen, 2012). There have also been other studies reporting heritabilities of 0.2 to 0.5 for lean using video image analysis (Rius-Vilarrasa et al, 2009;Einarsson et al, 2015;Johnson et al, 2015a,b) and computer tomography (CT; Jones et al, 2004;Karamichou et al, 2006;Kvame and Vangen, 2007;Lambe et al, 2008) procedures.…”

Section: Heritabilitymentioning

confidence: 95%

Genetic correlations between wool traits and carcass traits in Merino sheep1

Mortimer

Hatcher

Fogarty

et al. 2017

Journal of Animal Science

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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.

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“…Our heritability estimate of 0.25 ± 0.05 for ALW in female lambs following an extended period of untreated exposure to worm challenge (Table 6) was similar to estimates for ALW from other large data sets in New Zealand: 0.27 from Waldron et al (1992); 0.21 ± 0.04 from Bennett et al (1991). Our estimate for DS of 0.28 ± 0.06, (also measured following untreated exposure to worm challenge) was similar to that reported by Bisset et al (1992) (0.24 ± 0.08) but lower than that of Watson et al (1986) (0.50 ±0.22).…”

Section: Female Traitssupporting

confidence: 62%

Genetics of resilience to nematode parasites in Romney sheep

Bisset

Morris

Squire

et al. 1994

New Zealand Journal of Agricultural Research

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7533 Romney lambs, born in 1991 on six farms in the southern North Island of New Zealand, were studied as part of an investigation into the feasibility and implications of breeding sheep whose lambs require minimal anthelmintic treatment to maintain acceptable performance when exposed to challenge by nematode parasites ("resilience"). They were the progeny of 123 different sires. All flocks involved were genetically linked by the use of reference sires so that analyses could be carried out across farms. After weaning, ram lambs were mustered on 4 or 5 occasions for anthelmintic treatment. Treatment was administered on an individual basis as dictated by body condition and degree of breech-soiling ("selective drenching"). Drench requirement data including age at first drench (normalised by transformation to include the 5% of animals not requiring drench treatment), 5 binary scores denoting whether or not a lamb was drenched by Time 1, Time 2 ... Time 5 ("BY1, BY2... BY5"), and total number of drench treatments used over the 4-month study A94005Received 10 January 1994; accepted 1 July 1994 period (range 0-5), were subsequently used to assess resilience in these lambs. Their weaning weight, post-weaning liveweight gain, autumn liveweight, hogget liveweight, hogget fleece weight, and dag score were also examined. In ewe lambs, weaning weight, post-weaning liveweight gain, autumn liveweight, hogget liveweight, hogget fleece weight, dag score, faecal consistency score, and faecal worm egg count were examined before or after an extended period of exposure to natural nematode challenge without anthelmintic treatment. Date of birth, age of dam, and birth rank all significantly affected resilience traits in male lambs, largely as a result of their influence on weaning weight. Heritabilities of the traits proved to be relatively low (in the range 0.05-0.14). Nevertheless, genetic correlations between resilience traits in male progeny and production traits in their female half sibs showed that sires whose male progeny required fewer drench treatments to maintain acceptable condition (i.e. were more resilient to nematode challenge), had female progeny which had significantly higher than average growth rates and significantly lower than average breech-soiling (dags) under challenge (genetic correlations of 0.34-0.68; P < 0.05). Genetic correlations between resilience traits in male progeny and hogget fleece weight in their female half sibs were favourable but not significant. Results suggest that selection of lambs for any of the resilience traits examined simply on the basis of individual performance is unlikely to be practical because of low heritabilities. However, selection using breeding values based on progeny-testing of sires may provide worthwhile progress in a breeding programme. To select for resilience using a progeny-testing approach, the simplest of the traits is probably BY2 or age at first drench. The consequences of progeny-test selection with a series of index combinations as predictors are presented...

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Genetic and phenotypic parameter estimates for selection to improve lamb carcass traits

Cited by 29 publications

References 15 publications

Selection for lean weight based on ultrasound and CT in a meat line of sheep

Selection for lean weight based on ultrasound and CT in a meat line of sheep

Genetic correlations between wool traits and carcass traits in Merino sheep1

Genetics of resilience to nematode parasites in Romney sheep

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