title: Repeatability and phenotypic correlations for body weight and reproduction in commercial ostrich breeding pairs.
abstract: 1. Reproduction is an important aspect of ostrich farming, where income is mainly derived from hides and meat. No estimates of repeatability or phenotypic correlations for reproduction and body weight are currently available for commercial ostriches. 2. Means, standard deviations, repeatability coefficients and phenotypic correlations for and among reproductive traits and body weight were computed for the average yearly production of 42 to 67 mixed age ostrich breeding pairs maintained on the Klein Karoo Agricultural Development Centre from 1990 to 1994. The among-breeding-pair variance component was used in the repeatability estimations, as the pairing off of the same male:female combinations repeatedly resulted in the confounding of these effects. 3. Phenotypic correlations of male body weight with egg production performance (-0.20) and female body weight with hatchability percentage (-0.16) were negative. Correlations of egg production performance with infertility (-0.20) and hatchability (0.23) percentages were favourable. 4. The repeatability of annual adult body weight was 0.68 +/- 0.05 in male ostriches and 0.61 +/- 0.05 in females. 5. Ostrich reproduction traits were extremely variable. An appreciable portion of this variation could be attributed to the repeatable nature of breeding pair performance from year to year. All the reproduction traits analysed were moderately repeatable, ranging from 0.38 +/- 0.07 (hatchability percentage) to 0.51 +/- 0.06 (percentage of embryonic deaths). Egg production performance during the first breeding season of 17 breeding pairs for which data were available predicted subsequent performance satisfactorily, suggesting that selection decisions can be made at quite an early age.
authors.affiliation: Klein Karoo Agricultural Development Centre, Oudtshoorn, Republic of South Africa.
authors.forename: S J
authors.initials: SJ
authors.lastname: van Schalkwyk
authors.forename: S W
authors.initials: SW
authors.lastname: Cloete
authors.forename: J A
authors.initials: JA
authors.lastname: de Kock
mesh_terms: D000818:Animals; D001717:Birds / Q000196:embryology / Q000502:physiology*; D001835:Body Weight / Q000502:physiology*; D001947:Breeding; D047108:Embryonic Development; D005260:Female; D008297:Male; D010641:Phenotype; D015203:Reproducibility of Results; D012098:Reproduction / Q000502:physiology*; D012727:Sex Characteristics; D013019:South Africa