Genetic parameters for egg-, chick- and live-weight traits recorded in farmed ostriches (Struthio camelus)

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. (C) 2004 Elsevier B.V. All rights reserved.