Variance components for live weight, body measurements and reproductive traits of pair-matched ostrich females

Abstract

1. Estimates of genetic parameters for reproductive traits, live weight and body measurements were obtained using data from a pair-mated ostrich flock at Oudtshoorn in South Africa. Reproductive traits included total egg and chick production, along with hatchability percentage. Live weight, chest circumference and tail circumferences were recorded at the commencement and cessation of breeding. 2. Heritability estimates ('h'²) were 0·23 for egg production, 0·20 for chick production, 0·10 for hatchability, 0·20 to 0·34 for live weight, 0·12 for chest circumference and 0·30 to 0·38 for tail circumference. Female permanent environmental effects ('c'²) amounted to 0·18 for egg production, 0·18 for chick production, 0·21 for hatchability, 0·32 to 0·36 for live weight and 0·23 to 0·32 for chest circumference. Service sire exerted significant effects only on hatchability (0·22) and subsequently chick production (0·09). 3. Genetic correlations of reproductive traits with live weight were low to moderate, variable in sign, and did not differ significantly from zero. Correlations between live weight recorded at the beginning and end of the breeding season were unity for additive genetic and permanent environmental effects. 4. Egg and chick production were highly correlated genetically and phenotypically, with the genetic correlation exceeding the theoretical limit. In unconstrained analyses, hatchability was positively related to chick production, including at the service sire level. 5. Selection gains in the current flock and future generations are likely. No significant adverse relationships were found between live weight, body measurements and reproductive traits.