South African Journal of Animal Science

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Estimation of the additive and dominance variances in South African Landrace pigs

D Norris, L Varona, D P Visser, H E Theron, S F Voordewind, E A Nesamvuni


The objective of this study was to estimate dominance variance for number born alive (NBA), 21- day litter weight (LWT21) and interval between parities (FI) in South African Landrace pigs. A total of 26223 NBA, 21335 LWT21 and 16370 FI records were analysed. Bayesian analysis via Gibbs sampling was used to estimate variance components and genetic parameters were calculated from posterior distributions. Estimates of additive genetic variance were 0.669, 43.46 d2 and 9.02 kg2 for NBA, FI and LWT21, respectively. Corresponding estimates of dominance variance were 0.439, 123.68 d2 and 2.52 kg2, respectively. Dominance effects were important for NBA and FI. Permanent environmental effects were significant for FI and LWT21. It may be beneficial to evaluate non-additive genetic merit of individuals and families in addition to their transmitting abilities. A breeding program that capitalizes on non-additive genetic merit may be desirable.

Keywords: Non-additive genetic effects, Bayesian analysis, genetic parameters

South African Journal of Animal Science Vol. 36 (4) 2006: pp. 261-268

AJOL African Journals Online