Estimation of breed effects and non-additive genetic variation for ostrich slaughter and skin traits

Abstract

The study quantified breed effects and putative non-additive genetic variation for quantitative and qualitative skin traits of South African Black (SAB), Zimbabwean Blue (ZB), Kenyan Red (KR) ostriches and their reciprocal crosses. Data from SAB, ZB and their reciprocal crosses (n = 666 to 762), as well as of SAB, KR, and their reciprocal crosses (n = 544 to 594), were analysed separately. The 2x2 diallel crossbreeding design was used for assessing the crossbred combinations, while degrees of freedom for genetic group were used to derive linear contrasts to partition the effects of additive breed, heterosis and the damline effect. The ZB strain outperformed SAB birds for most size-related traits. Additive breed effects were significant for slaughter weight (10.4%), crust skin size (3.9%), crown length (1.5%) and nodule shape score (1.6%). Significant heterosis were found for slaughter weight (4.3%), crust skin size (1.7%), nodule size score (3.7%) and hair follicle score (12%). Significant damline effects were observed for skin weight (4.1%), crown shape (2.4%) and hair follicle score (4.1%). In SAB, KR and their reciprocal crosses analysis, additive breed effects were mostly similar to ZB strain with SAB. Heterosis estimates were significant for slaughter weight (5.7%), crust skin size (2.9%), crown length (1.7%) and nodule size score (4.4%). Damline effect was significant for slaughter weight (3.7%) and nodule size score (3.8%). It was concluded that ZB and KR birds outperformed their SAB contemporaries for size and size-related traits, and that commercial crossbreeding could improve size-related traits of hybrids over the mid-parent value of purebreds.