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Phenotypic and genetic parameters of productivity in Galway ewes

Published online by Cambridge University Press:  02 September 2010

G. J. More O'Ferrall
G. J. More O'Ferrall
Affiliation:
An Foras Talúntais, Dunsinea, Castleknock, Co. Dublin, Ireland
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Summary

Records from a selection flock of Galway ewes collected over a 6-yr period (1966 to 1971) were used to obtain estimates of the phenotypic and genetic parameters of ewe productivity. The number of lambs born (NLB) and weaned (NLW), the weight of lamb weaned (WLW), ewe body weight (EBW) and greasy fleece weight (GFL) were used as measures of productivity, mean values being 1·25, 0·88, 25·6 kg, 52·8 kg and 2·8 kg, respectively. Each ewe's annual performance was adjusted to a 4-yr-old ewe equivalent and expressed as a deviation from the appropriate flock × year subgroup mean; these deviations were combined into a single index value for each ewe for NLB, NLW and WLW. Records for 975 individual ewes representing 84 sires which had three or more progeny were used in a half sib analysis of variance.

Estimates of heritability were 0·18, 0·24 and 0·25 for NLB, NLW and WLW based on index record and 0·07, 0·16 and 0·30 respectively for 2-yr-old ewes. Heritability estimates of EBW and GFL were 0·73 and 0·52 respectively. The genetic correlations between EBW and NLB2, NLW2, WLW2 and GFL were 0·85, 0·42, 0·62 and 0·53 respectively; those between EBW and index records were slightly negative. Phenotypic correlations were generally lower than the corresponding genetic ones.

Ewes born as multiples were more productive than singles. They were 1·8 kg lighter (P < 0·01) at 18 mo and weaned 2·5 kg more lamb (P < 0·05) at 2 yr of age. The repeatability of NLB ranged from 0 to 0·2.

Type
Research Article
Information
Animal Production , Volume 23 , Issue 3 , December 1976 , pp. 295 - 304
Copyright
Copyright © British Society of Animal Science 1976

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References

REFERENCES

Basuthakur, A. K., Burfening, P. J.Van Horn, J. L. and Blackwell, R. L. 1973. A study of some aspects of lifetime production in Targhee and Columbia sheep. J. Anim. Sci. 36: 813–820.CrossRefGoogle Scholar
Bowman, J. C. 1966. Meat from sheep. Anim. Breed. Abstr. 34: 293–319.Google Scholar
Cunningham, E. P. 1969. Animal Breeding Theory p. 205. Landbruksbokhandelen/ Universitetsforlaget, Vollebekk, Oslo.Google Scholar
Dickerson, G. 1970. Efficiency of animal production—molding the biological components. J. Anim. Sci. 30: 849–859.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. Anim. Prod. 19: 33–45.Google Scholar
Hanrahan, J. P. 1974. Maternal effects and selection response. Proc. 1st World Congr. Genet. Appld Anim. Prod. 3: 391–395.Google Scholar
Hanrahan, J. P. and Timon, V. M. 1974. Ovulation rate and response to selection in Galway sheep. Proc. Br. Soc. Anim. Prod. (New Series) 3: 96 (Abstr.).Google Scholar
Harvey, W. R. 1960. Least squares analysis of data with unequal sub-class numbers. United States Department of Agriculture, ARS-20–8 (Mimeograph).Google Scholar
Kempthorne, O. 1963. An Introduction to Genetic Statistics p. 232. Wiley, New York.Google Scholar
Large, R. V. 1970. The biological efficiency of meat production in sheep. Anim. Prod. 12: 393–401.Google Scholar
Purser, A. F. 1965. Repeatability and heritability of fertility in hill sheep. Anim. Prod. 7: 75–82.Google Scholar
Rae, A. L. 1956. The genetics of the sheep. Adv. Genet. 8: 189–265.Google Scholar
Reeve, E. C. R. and Robertson, F. W. 1953. Factors affecting multiple births in sheep. Anim. Breed. Abstr. 21: 211–224.Google Scholar
Shelton, N. and Menzies, J. W. 1968. Genetic parameters of some performance characteristics of range fine-wool ewes. J. Anim. Sci. 27: 1219–1223.Google Scholar
Terrill, C. E. 1958. Fifty years of progress in sheep breeding. J. Anim. Sci. 17: 944–959.CrossRefGoogle Scholar
Turner, H. N. 1969. Genetic improvement of reproduction rate in sheep. Anim. Breed. Abstr. 37: 545–563.Google Scholar
Turner, H. N. and Dunlop, A. A. 1974. Selection for wool production. Proc. 1st World Congr. Genet. Appld Anim. Prod. 1: 739–756.Google Scholar
Turner, H. N. and Young, S. S. Y. 1969. Quantitative Genetics in Sheep Breeding. Macmillan, London.Google Scholar
Wallace, L. R. 1964. Breeding performance of Romneys improves in long-term experiment. N.Z. Jl. Agric. 109: 417.Google Scholar
Young, S. S. Y., Turner, H. N. and DOLLING, C. H. S. 1963. Selection for fertility in Australian Merino sheep. Aust. J. agric. Res. 14: 460–482.Google Scholar