Selection for lean growth in terminal sire sheep to produce leaner crossbred progeny

Lewis, R. M.; Simm, G.; Dingwall, W.S.; Murphy, Simon

doi:10.1017/s1357729800028368

Cited by 35 publications

(28 citation statements)

References 17 publications

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“…Therefore we anticipated differences in lean growth rate between sire categories would be expressed in the performance of their crossbred progeny. Such an effect has been observed previously (Lewis et al, 1996Simm and Murphy, 1996;Jones et al, 1999), and here.…”

Section: Comparison Of Index Categoriessupporting

confidence: 91%

“…The results from other experiments have also shown that the use of the lean growth index has increased lean weight in the carcass while reducing fat weight (Lewis and Emmans, 2007). Lewis et al (1996) found that commercial lambs sired by high lean growth index sires produced leaner and more valuable carcasses. Corroborating these results, van Heelsum et al (2003), studying the Scottish and Welsh Mules used as dams in the current study, found that their Bluefaced Leicester sires with greater index scores produced wethers with more lean and less fat content in all carcass joints (e.g., shoulder, leg, and loin).…”

Section: Sire Index and Breed Influencesmentioning

confidence: 90%

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Index selection in terminal sires improves early lamb growth1

Márquez

Haresign

Davies

et al. 2012

Journal of Animal Science

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ABSTRACT:The use of terminal sires (TS) for crossbreeding is integral to the UK sheep industry where approximately 71% of market lambs are sired by TS rams. Early growth of these crossbred lambs affects profitability. The objectives of this study were i) to evaluate the effectiveness of index selection among TS on BW and ADG of their crossbred offspring; and ii) to compare the efficacy of that selection within TS breeds. The most widely used TS breeds in the United Kingdom are Charollais, Suffolk, and Texel. These participated in sire referencing schemes in which they were evaluated on a lean growth index designed to increase carcass lean weight at a given age. From 1999 to 2002, approximately 15 high and 15 low lean growth index rams per breed (93 in total, differing in index on average by 4.6 SD) were selected from within their sire referencing schemes and mated to Welsh and Scottish Mule ewes. Their crossbred offspring were reared commercially on 3 experimental farms in England, Scotland, and Wales. A total of 6,515 lambs were born between 2000 and 2003. Lambs were weighed at birth (BWT), 5 wk (5WT), and 10 wk (10WT), and their ADG from birth to 10 wk was calculated. Lambs sired by high index rams were on average, across breeds, heavier at all ages (P < 0.01) with 0.07 ± 0.03, 0.3 ± 0.1, and 0.4 ± 0.1 kg greater BWT, 5WT, and 10WT, respectively. Their ADG was 5.1 ± 1.9 g/d greater than low-index-sired lambs (P < 0.01). Suffolk-sired lambs were on average heavier at all ages, with greater ADG, whereas Charollais-sired lambs were lightest with smallest ADG. Overall, there was no significant interaction between sire index and sire breed (P > 0.10). Within Suffolk-sired lambs, there was little difference between high and low index sires for the traits studied (P > 0.3). High and low index Charollais-sired lambs differed in BWT (0.09 ± 0.04 kg) and 5WT (0.3 ± 0.1 kg), and Texel-sired lambs differed in 5WT (0.5 ± 0.1 kg), 10WT (0.9 ± 0.2 kg), and ADG (10.2 ± 3.3 g/d; P < 0.01). Lambs from Scottish Mule dams were heavier, with greater ADG, than lambs born to Welsh Mules (P < 0.01). Lambs reared in Scotland were heavier at all ages (P < 0.01). The results suggest that using index selection in TS can improve the growth of their commercial offspring reared on grass.

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Section: Comparison Of Index Categoriessupporting

confidence: 91%

Section: Sire Index and Breed Influencesmentioning

confidence: 90%

Index selection in terminal sires improves early lamb growth1

Márquez

Haresign

Davies

et al. 2012

Journal of Animal Science

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“…While genotype by environment interactions probably exist, they tend to be modest in their impact (e.g. Lewis et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Industry benefits from recent genetic progress in sheep and beef populations

Pr¹,

Nieuwhof

Ge³

et al. 2007

Animal

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An analytical model that evaluates the benefits from 10 years of genetic improvement over a 20-year time frame was specified. Estimates of recent genetic trends in recorded traits, industry statistics and published estimates of the economic values of trait changes were used to parameterise the model for the UK sheep and beef industries. Despite rates of genetic change in the relevant performance-recorded breeding populations being substantially less than theoretical predictions, the financial benefits of genetic change were substantial. Over 20 years, the benefits from 10 years of genetic progress at recently achieved rates in recorded hill sheep, sheep crossing sire and sheep terminal sire breeding programmes was estimated to be £5.3, £1.0 and £11.5 million, respectively. If dissemination of genetic material is such that these rates of change are also realised across the entire ram breeding industry, the combined benefits would be £110.8 million. For beef cattle, genetic evaluation systems have been operating within all the major breeds for some years with quite widespread use of performance recording, and so genetic trends within the beef breeds were used as predictors of industry genetic change. Benefits from 10 years of genetic progress at recent rates of change, considering a 20-year time frame, in terminal sire beef breeds are expected to be £4.9 million. Benefits from genetic progress for growth and carcass characters in dual-purpose beef breeds were £18.2 million after subtraction of costs associated with a deterioration in calving traits. These benefits may be further offset by unfavourable associated changes in maternal traits. Additional benefits from identification and use of the best animals available from the breeding sector for commercial matings through performance recording and genetic evaluation could not be quantified. When benefits of genetic improvement were expressed on an annual present value basis and compared with lagged annual investment costs to achieve it, the internal rate of return (IRR) on the combined investment in sheep and beef cattle was 32%. Despite a much higher rate of participation in performance recording, the present value of benefits and the IRR were lower for beef cattle than for sheep. The implications of these results for future national and industry investment in genetic improvement infrastructure were discussed.

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“…The lack of differences in the conformation of high-and lowindex-sired lambs indicates that selection for lean growth will, at least, not adversely affect conformation avoiding potential discounts at harvest. Live conformation score depends on both muscling and fat (Lewis et al, 1996;Jones et al, 1999;Navajas et al, 2008). Positive genetic correlations have been found between logUFD, UMD, and OCS, indicating that selection for UMD may improve conformation, but selection against logUFD could lead to a decrease in conformation score (van Heelsum et al, 2001).…”

Section: Finished Condition Score and Conformationmentioning

confidence: 99%

“…A lean growth index was adopted by the UK terminal sire sheep industry to improve the lean content of the carcass (Simm and Dingwall, 1989). Although there have been clear benefi ts within experimental populations (Lewis et al, 1996;Simm and Murphy, 1996;Simm et al, 2002), evidence from commercial settings is more limited (Márquez et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Index selection in terminal sires improves lamb performance at finishing1

Márquez

Haresign

Davies

et al. 2013

Journal of Animal Science

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Lamb meat is often perceived by consumers as fatty, and consumption has decreased in recent decades. A lean growth index was developed in the UK for terminal sire breeds to increase carcass lean content and constrain fat content at a constant age end point. The purposes of this study were 1) to evaluate the effects of index selection of terminal sires on their crossbred offspring at fi nishing and 2) to evaluate its effectiveness within terminal sire breeds. Approximately 70% of lambs marketed in the UK have been sired by rams of breeds typically thought of as specialized terminal sires. The most widely used are Charollais, Suffolk, and Texel. These breeds participated in sire referencing schemes from the early 1990s by sharing rams among fl ocks selected on the lean growth index. From 1999 to 2002 approximately 15 "high" and 15 "low" lean growth index score rams were selected from within their sire referencing schemes and mated to Welsh and Scottish Mule ewes. Their crossbred offspring were commercially reared on 3 farms in the UK. Lambs were fi nished to an estimated 11% subcutaneous fat by visual evaluation. At fi nishing, lambs were weighed, ultrasonically scanned, and assessed for condition score and conformation. Records were obtained for 6356 lambs on fi nishing BW (FWT), ultrasonic muscle depth (UMD), ultrasonic fat depth, overall condition score (OCS), and conformation of gigot, loin, and shoulder. Ultrasonic fat depth was log transformed (logUFD) to approach normality. High-index-sired lambs were heavier at fi nishing (1.2 ± 0.2 kg) with thicker UMD (0.7 ± 0.2 mm) and less logUFD (0.08 ± 0.01 mm; P < 0.05). There were no differences in OCS or conformation based on the sire index or breed (P > 0.08). Suffolk-sired lambs were heavier than Charollais (1.0 ± 0.3 kg), which were heavier than Texel (0.9 ± 0.3 kg; P < 0.001). Texel-sired lambs had thicker UMD than Charollais (0.7 ± 0.2 mm; P < 0.001) but were not different than Suffolk. Charollais-sired lambs had greater logUFD than both Texel (0.098 ± 0.016 mm) and Suffolk (0.061 ± 0.017 mm) sired lambs (P < 0.001). Within a breed, high-and low-index-sired lambs differed in performance with the exceptions of FWT and UMD in Suffolks. Index selection produced heavier and leaner lambs at fi nishing. Producers have fl exibility in choosing the terminal sire that best fi ts their production system.

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Selection for lean growth in terminal sire sheep to produce leaner crossbred progeny

Cited by 35 publications

References 17 publications

Index selection in terminal sires improves early lamb growth1

Index selection in terminal sires improves early lamb growth1

Industry benefits from recent genetic progress in sheep and beef populations

Index selection in terminal sires improves lamb performance at finishing1

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