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An evaluation of performance-testing of rams using artificial rearing

  • J. B. Owen (a1), Lesley E. Brook (a1), J. L. Read (a2), D. E. Steane (a2) and W. G. Hill (a3)...


In two trials, male Suffolk sheep were weaned at birth and reared artificially. Animals were ranked on weight at about 90 days and groups comprising the fastest- and slowest-growing animals were selected. The selected rams were subsequently progeny-tested to the same age, with some progeny reared with their dams in normal field conditions and others reared artificially.

In Trial I, performance tests were obtained on 35 rams and progeny tests of seven of these (three low and four high), with records on 34 artificially reared and 144 naturally reared progeny on one farm. The regressions of progeny on sire 90-day weight were 0·29 ± 0·12 and 0·19±0·09, respectively.

In Trial II, performance tests were obtained on 86 rams, sampled from five source flocks. Rams were selected in pairs of high and low performance from each source, and both members of the pair sent to the same one of seven farms for progeny testing. Ten pairs had progeny tests, comprising 62 artificially reared and 567 naturally reared progeny. The regressions of progeny on sire weight were, respectively, 0·05 ± 0·06 and 0·13 ± 0·03 if source of sire was fitted in the model, and little different, 0·06 ±0·05 and 0·14 ± 0·03 if source of sire was ignored. Progeny from a 2nd year from some sires in Trial II gave rather smaller regression coefficients: 0·06 or 0·09, with source of sire fitted or ignored, respectively.

Taking the two main trials together the pooled estimates (ignoring source of sire) of doubled progeny-on-sire regression for 90-day weight were 0·20 ± 0·10 for artificial rearing (a heritability estimate) and 0·30 ± 0·06 for natural rearing. These results suggest that early weaning is an effective method of selecting sires for growth rate.



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Bowman, J. C. 1968. Genetic variation of body weight in sheep. In Growth and Development of Mammals, (ed. Lodge, G. A. and Lamming, G. E.), pp. 291308. Butterworth, London.
Bowman, J. C. and Broadbent, J. S. 1966. Genetic parameters of growth between birth and 16 weeks in Devon cross sheep. Anim. Prod. 8: 129135.
Bradford, G. E. 1974. Breeding plans for improvement of meat production and carcass merit in the meat breeds of sheep. In 1st Wld Congr. Genetics applied to Livestock Production. 1: 725738. Editorial Garsi, Madrid.
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: 99106.
Davies, D. A. R., Owen, J. B. and Read, J. L. 1978. Artificial rearing as a system for evaluating male lambs. Anim. Prod. 26: 3138.
Ercanbrack, S. K. and Price, D. A. 1972. Selecting for weight and rate of gain in non-inbred lambs. J. Anim. Sci. 34: 713725.
Harrington, R. B., Brothers, D. G. and Whiteman, J. V. 1962. Heritability of gain of lambs measured at different times and by different methods J. Anim. Sci. 21: 7881.
Harvey, W. A. 1972. Least Squares and Maximum Likelihood General Purpose Program. 252K Mixed Model Version. (Mimeograph.)
Hill, W. G. and Thompson, R. 1977. Design of experiments to estimate off spring-parent regression using selected parents. Anim. Prod. 24: 163168.
Kempthorne, O. and Tandon, O. B. 1953. The estimation of heritability by regression of offspring on parent. Biometrics 9: 90100.
Meat and Livestock Commission. 1972. Sheep Improvement. Scientific Study Group Report. Meat and Livestock Commission, Bletchley, Buckinghamshire.
Olson, L. W., Dickerson, G. E. and Glimp, H. A. 1976. Selection criteria for intensive market lamb production: growth traits. J. Anim. Sci. 43: 7889.
Owen, J. B. 1971. Performance Recording in Sheep. Commonwealth Agricultural Bureaux, Farnham Royal, Buckinghamshire.
Vogt, D. W.Carter, R. C. and McClure, W. H. 1967. Genetic and phenotypic parameter estimates involving economically important traits in sheep. J. Anim. Sci. 26: 12321238.

An evaluation of performance-testing of rams using artificial rearing

  • J. B. Owen (a1), Lesley E. Brook (a1), J. L. Read (a2), D. E. Steane (a2) and W. G. Hill (a3)...


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