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A genetic analysis of the components of lifetime productivity in Scottish Blackface sheep

Published online by Cambridge University Press:  02 September 2010

K. D. Atkins
K. D. Atkins
Affiliation:
AFRC Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
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Abstract

Reproductive performance, body growth, wool production and ewe survival were examined in Scottish Blackface sheep. The data set was from a large randomly selected population maintained under hill conditions between 1954 and 1974. Paternal half-sib analyses of variance were used to estimate heritabilities and genetic correlations, while maternal half-sib analyses of variance indicated the relative importance of maternal effects (both genetic and environmental).

Among reproductive components, the heritability of fertility (ewes lambing per ewe mated) and lamb survival (lambs weaned per lamb born) were about zero. Litter size (lambs born per ewe lambing) had an estimated heritability of 0·12 (s.e. 0·04) and a repeatability of 0·22 (s.e. 0·02), indicating some scope for improvement. Additionally, the strong genetic correlation between adult body weight and litter size (0·66, s.e. 0·18) suggested greater response from a combination of indirect selection (on body weight) and direct selection (on dam's litter size). Prior to weaning, direct genetic effects on body weight were very small (heritability less than 0·1) with a large influence of maternal environment. After weaning, these maternal influences gradually diminished and the heritability of weight increased. Genetic correlations between body weights showed a similar increasing trend with age. Genetic improvement of early growth rate would be more effective by selecting on a post-weaning rather than a pre-weaning body weight. Fleece weight had a high heritability (about 0·5) but was genetically uncorrelated with other measures of performance. Ewe survival had a small genetic component although estimates of heritability were very imprecise.

Type
Research Article
Information
Animal Production , Volume 43 , Issue 3 , December 1986 , pp. 405 - 419
Copyright
Copyright © British Society of Animal Science 1986

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References

REFERENCES

Atkins, K. D. and Thompson, R. 1986. Predicted and realized responses to selection for an index of bone length and body weight in Scottish Blackface sheep. 1. Responses in the index and component traits. Animal Production 43: 421–435.Google Scholar
Baker, R. L., Clarke, J. N., Carter, A. H. and Diprose, G. D. 1979. Genetic and phenotypic parameters in New Zealand Romney sheep. 1. Body weights, fleece weights, and oestrous activity. New Zealand Journal of Agricultural Research 22: 9–21.CrossRefGoogle Scholar
Baker, R. J. and Nelder, J. A. 1978. The GLIM System, Release 3. Numerical Algorithms Group, Oxford.Google Scholar
Becker, W. A. 1975. Manual of Quantitative Genetics. 3rd ed. Pullman, Washington State University.Google Scholar
Ch'ang, T. S. and Rae, A. L. 1972. The genetic basis of growth, reproduction, and maternal environment in Romney ewes. II. Genetic covariation between hogget characters, fertility, and maternal environment of the ewe. Australian Journal of Agricultural Research 23: 149–165.CrossRefGoogle Scholar
Clarke, J. N. 1972. Current levels of performance in the Ruakura Fertility flock of Romney sheep. Proceedings of the New Zealand Society of Animal Production 32: 99–111.Google Scholar
Cue, R. I. 1981. A genetic analysis of lamb mortality in hill sheep. Ph.D. Thesis, University of Edinburgh.Google Scholar
Cunningham, E. P. and Gjedrem, T. 1970. Genetic control of ewe body weight in selection for higher wool and lamb output. Ada Agriculturae Scandinavica 20: 194–204.CrossRefGoogle Scholar
Eikje, E. D. 1975. Studies on sheep production records. VII. Genetic, phenotypic and environmental parameters for productivity traits of ewes. Ada Agriculturae Scandinavica 25: 242–252.CrossRefGoogle Scholar
Forrest, P. A. and Bichard, M. 1974. Analysis of production records from a lowland sheep flock. 3. Phenotypic and genetic parameters for reproductive performance. Animal Production 19: 33–45.Google Scholar
Hanrahan, J. P. 1979. Genetic and phenotypic aspects of ovulation rate and fecundity in sheep. 21st Poultry Breeders Roundtable, Glasgow.Google Scholar
Land, R. B., Atkins, K. D. and Roberts, R. C. 1983. Genetic improvement of reproductive performance. In Sheep Production (ed. Haresign, W.), pp. 515–535. Butterworths, London.Google Scholar
McGuirk, B. J. 1973. The inheritance of production characters in Merino sheep. Ph.D. Thesis, University of Edinburgh.Google Scholar
Martin, T. G., Salks, D. I., Smith, C. and Nicholson, D. 1980. Phenotypic and genetic parameters for lamb weights in a synthetic line of sheep. Animal Production 30: 261–269.Google Scholar
Morley, F. H. W., White, D. H., Kenney, P. A. and Davis, I. F. 1978. Predicting ovulation rate from liveweight in ewes. Agricultural Systems 3: 27–45.CrossRefGoogle Scholar
Piper, L. R. and Bindon, B. M. 1977. The genetics of early viability in Merino sheep. Proceedings of 3rd International Congress of the Society for the Advancement of Breeding Researches in Asia and Oceania (SABRAO), Canberra, Animal Breeding Papers, pp. 10.17–10.22Google Scholar
Piper, L. R., Hanrahan, J. P., Evans, R. and Bindon, B. M. 1982. Genetic variation in individual and maternal components of lamb survival in Merinos. Proceedings of the Australian Society of Animal Production 14: 29–30.Google Scholar
Purser, A. F. 1965. Repeatability and heritability of fertility in hill sheep. Animal Production 7: 75–82.Google Scholar
Purser, A. F. and Roberts, R. C. 1964. The effect of treatment during first winter on the subsequent performance of Scottish Blackface ewes. Animal Production 6: 273–284.Google Scholar
Robertson, A. 1962. Weighting in the estimation of variance components in the unbalanced single classificiation. Biometrics 18: 413–417.CrossRefGoogle Scholar
Shelton, M. and Menzies, J. W. 1970. Repeatability and heritability of components of reproductive efficiency in fine-wool sheep. Journal of Animal Science 30: 1–5.CrossRefGoogle ScholarPubMed