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Estimates of (co)variances due to direct and maternal effects for body weights in Timahdite sheep

Published online by Cambridge University Press:  18 August 2016

I. Boujenane  and
J. Kansari
I. Boujenane*
Affiliation:
Department of Animal Production, Institut Agronomique et Vétérinaire Hassan II, BP 6202 Rabat-Instituts, 10101 Rabat, Morocco
J. Kansari
Affiliation:
Société Nationale de Développement de l'Elevage, 5 Rue de Salé, Tour Hassan, Rabat, Morocco
*
† Corresponding author E-mail:[email protected]
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Abstract

Genetic parameters for body weights in Timahdite sheep were estimated using records of 10370 lambs from the ‘Société Nationale de Développement de l’Elevage’ born in 1988-89 to 1998-99. An animal model with derivativefree restricted maximum likelihood procedures was used. Random effects were direct and maternal additive genetic, maternal permanent environmental, and error. Direct and maternal heritability estimates were 0·05 and 0·05 for birth weight, 0·02 and 0·07 for weight at 30 days, 0·07 and 0·08 for weight at 70 days, 0·06 and 0·01 for weight at 90 days. Estimates of fraction of variance due to maternal permanent environmental effects were close to zero, except for weight at 90 days. Genetic correlations between direct and maternal genetic effects were –0·55, –0·51, –0·50 and –0·17 for body weights at birth, 30, 70 and 90 days, respectively. Estimates of direct genetic correlations among body weights were positive and high, ranging from 0·69 to unity. Phenotypic correlations were positive and moderate to high, being lower than their corresponding direct genetic correlations. Estimates of correlations between maternal genetic effects among weights were positive and high, varying from 0·79 to unity. Cross-correlations between direct genetic effects for one weight and maternal genetic effects for another weight were consistently negative, ranging from –0·05 to –0·63. These results indicate that selecting for improved maternal and/or direct effects in Timahdite sheep is expected to generate only slow genetic progress in terms of early growth.

Keywords

body weightcorrelationheritabilitymaternal effectssheep
Type
Breeding and genetics
Information
Animal Science , Volume 74 , Issue 3 , June 2002 , pp. 409 - 414
Copyright
Copyright © British Society of Animal Science 2002

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