Resumo

CLOETE, S.W.P.; BUNTER, K.L.; BRAND, Z.  e  LAMBRECHTS, H.. (Co)variances for reproduction, egg weight and chick weight in ostriches. S. Afr. j. anim. sci. [online]. 2004, vol.34, n.2, pp.17-19. ISSN 2221-4062.

The study investigated genetic parameters for egg and chick production recorded over an 8-month breeding season, as well as average egg and chick weight for pair-bred ostrich females. Estimates of h² were moderate for reproduction traits and very high for average egg and chick weight, where all traits were expressed as a trait of the dam. Genetic and phenotypic correlations were positive in sign for all trait combinations. Selection for an increased reproduction rate would thus not lead to an unwanted (downwards) correlated response in average egg or chick weight. Averaged annual breeding values for egg and chick production in breeding females increased at 1.4 and 2.3% per year, respectively. These results indicate that the genetic improvement of ostriches is feasible, provided that obstacles hampering it are overcome.

Palavras-chave : Breeding values; chick production; egg production; heritability; genetic correlations.

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