Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-18T18:42:50.123Z Has data issue: false hasContentIssue false
  • English
  • Français

Responses in lamb performance from selection on sire 100-day weight

Published online by Cambridge University Press:  02 September 2010

N. D. Cameron  and
C. Smith
N. D. Cameron
Affiliation:
AFRC Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
C. Smith
Affiliation:
AFRC Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
Get access

Abstract

Forty-one Texel and Texel-Oxford sires were selected over 5 years (1978-82) on high and low adjusted 100-day weight from 174 ram lambs artificially reared from birth and performance tested. The correlated responses to selection were measured in 1103 crossbred progeny, out of an experimental group of crossbred ewes, the progeny being naturally reared in field conditions. Hierarchical analysis of variance was performed, fitting the usual fixed effects and interactions. Co-heritabilities (rAh2h2; rA is the genetic correlation between traits with heritabilities h12 and h22) were estimated from offspring-parent regression and from the realized responses to selection. The selection differentials achieved (1·70 standard deviations in 100-day weight between high- and low-weight sires) were lower than expected, due to mating difficulties, mortality and other requirements for the stock. The co-heritabilities for growth traits were generally positive but small (mean 0·08; s.e. 0·08). Though not statistically significant, lambs slaughtered at a fixed weight from the high-weight rams were slaughtered earlier with lighter and leaner carcasses, as expected. Similarly, lambs slaughtered according to fat cover from high-weight rams were slaughtered later with heavier slaughter and carcass weights. Generally, the co-heritabilities for carcass traits were not significantly different from zero for either slaughter group. On the basis of these results, selection on ram 100-day weight with artificial rearing may not offer any advantage over natural rearing in the improvement of lamb growth and carcass traits.

Type
Research Article
Information
Animal Production , Volume 41 , Issue 2 , October 1985 , pp. 227 - 233
Copyright
Copyright © British Society of Animal Science 1985

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Baker, R. L., Wickham, B. W. and Morris, C. A. 1982. The accuracy of central bull performance tests in New Zealand as evaluated by subsequent progeny testing. Proc. 2nd Wld Congr. Genet. Appl. Livest. Prod., Madrid. Vol. 8, pp. 300–304. Editorial Garsi.Google Scholar
Broadbent, J. S. and Watson, J. H. 1967. Sires own performance as an indication of progeny performance in testing Suffolk rams for growth rate. Anim. Prod. 9: 99–106.Google Scholar
Cameron, N. D. and Drury, D. J. 1985. Comparison of terminal sire breeds for growth and carcass traits in crossbred lambs. Anim. Prod. 40: 317–324.Google Scholar
Croston, D., Read, J. L., Jones, D. W., Steane, D. E. and Smith, C. 1983. Selection on ram 18-month weight to improve lamb growth rate. Anim. Prod. 36: 159–164.Google Scholar
Falconer, D. S. 1981. Introduction to Quantitative Genetics. 2nd ed. Longman, London.Google Scholar
Hill, W. G. 1970. Design of experiments to estimate heritability by regression of offspring on selected parents. Biometrics 26: 566–571.CrossRefGoogle ScholarPubMed
Hill, W. G. 1971. Design and efficiency of selection experiments for estimating genetic parameters. Biometrics 27: 293–311.CrossRefGoogle ScholarPubMed
Hocking, R. R. 1976. The analysis and selection of variables in linear regression. Biometrics 32: 1–49.CrossRefGoogle Scholar
Meat and Livestock Commission. 1981. Lamb Carcase Production: Planning to Meet Your Market. Meat and Livestock Commission, Milton Keynes.Google Scholar
Meat and Livestock Commission. 1983. Sheep Yearbook. Meat and Livestock Commission, Milton Keynes.Google Scholar
Owen, J. B., Brook, L. E., Read, J. L., Steane, D. E. and Hill, W. G. 1978. An evaluation of performance-testing of rams using artificial rearing. Anim. Prod. 27: 247–259.Google Scholar
Robertson, A. 1977. The effect of selection on the estimation of genetic parameters. Z. Tierzücht. ZüchtBiol. 94: 131–135.CrossRefGoogle Scholar
Standal, N. 1984. Genotype-testing regime interaction estimated from station and farm test data. 35th A. Meet. Eur. Ass. Anim. Prod., Hague, Paper GP1.7.Google Scholar
Wolf, B. T., Smith, C., King, J. W. B. and Nicholson, D. 1981. Genetic parameters of growth and carcass composition in crossbred Iambs. Anim. Prod. 32: 1–7.Google Scholar
Yamada, Y. 1968. On the realised heritability and genetic correlation estimated from double selection experiments when two characters are measured. Jap. Poult. Sci. 5: 148–151.CrossRefGoogle Scholar