Abstract
Estimates of genetic parameters for egg weight (EGWT), hatched chick weight (CHWT) and live weights recorded at 3 (LW3), 6 (LW6), 10 (LW10) or 14 months of age (SLWT) were obtained using an animal model, with data recorded in a commercially managed pair-breeding ostrich flock. Significant systematic effects included production year and month (seasonal effects), egg position in the laying sequence, hen age and parental diet for egg and chick weights; or seasonal effects, weighing date and age at weighing for live weight traits. Estimates of heritabilities were moderate, ranging from 0.15±0.03 for CHWT to 0.28±0.10 for SLWT. The exception was live weight at 3 months, for which no significant additive variation was detected. Maternal genetic and permanent environmental effects ( m 2 and c 2) explained 25–30% each of phenotypic variation for EGWT and CHWT but were less important for juvenile live weights ( m 2 was not significant and c 2<10%). Correlations between random effects for EGWT and CHWT were very high, resulting in a phenotypic correlation ( r p) of 0.84±0.01. Genetic correlations ( r g) between EGWT and CHWT or among LW6, LW10 and SLWT were close to unity. EGWT, and to a lesser extent CHWT, were not strongly associated with the later live weights ( r g: −0.24±0.24 to 0.36±0.23; r p: 0.04±0.05 to 0.15±0.04). Parameters indicate that ostrich live-weight traits will respond to selection.
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