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Estimates of genetic parameters of growth rate in sheep with reference to the method of estimation

Published online by Cambridge University Press:  02 September 2010

E. Salah  and
E. Galal
E. Salah
Affiliation:
Desert Institute, Matarya, Cairo, Egypt, U.A.R.
E. Galal
Affiliation:
Desert Institute, Matarya, Cairo, Egypt, U.A.R.
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Extract

There were 563 lambs in the study. They were single Barki lambs born during the period 1961–62 to 1965–66 in Ras El-Hekma Desert Research Station (U.A.R.). All lambs were weighed at birth and at weaning. From 1963–64 onward lambs were weighed nearly every 15 days.

Two methods of estimating growth rate were compared:

R1 = weaning weight — birth weight/age at weaning

and R2 = the regression coefficient of weight on age. The effect of method of estimation on heritabilities and genetic and phenotypic correlations was examined.

Heritability estimates of birth weight, R1 and genetic and phenotypic correlations between them were 0·18 ± 0·10, 0·24 ± 0·11, 0·50 and 0·12 respectively. From the data collected during the period 1963–64 to 1965–66 alone the heritability estimates of birth weight, R1 and R2 and the genetic and phenotypic correlations between birth weight and each of R1 and R2 were 0·15 ± 0·14, 0·39 ± 0·20 and 0·39 ± 0·20; 0·84 and 0·96; 0·28 and 0·27 respectively.

For preweaning growth rate the method of dividing the gain in weight until weaning by age at weaning was virtually as good a method as using the regression of body weight on age. The correlation between the two methods was estimated as 0·91.

Type
Research Article
Information
Animal Production , Volume 10 , Issue 1 , February 1968 , pp. 109 - 112
Copyright
Copyright © British Society of Animal Science 1968

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References

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