Abstract

THEUNISSEN, A.; SCHOLTZ, M.M.; NESER, F.W.C.  and  MACNEIL, M.D.. Crossbreeding to increase beef production: additive and non-additive effects on weight traits. S. Afr. j. anim. sci. [online]. 2013, vol.43, n.2, pp.143-152. ISSN 2221-4062.

Using breed differences effectively facilitates high productivity and profitability. Thus, the objective of the study was to estimate direct and maternal additive and heterosis effects for growth traits (birth weight, weaning weight, 19-month weight of heifers and cow weight) from five purebred and 24 crossbred breed types. Afrikaner (A), Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) were evaluated as purebreds and as sire breeds on A and F1 BA, CA, HA and SA females. Breed additive effects were expressed as deviations from A. Effects of intra-breed genetic trend were assumed to be zero throughout. Solutions for the breed additive and heterosis effects were used to predict performance of the crossbred breed types to verify the adequacy of the genetic model. Correlations of observed and predicted means ranged from 0.87 for weaning weight to 0.94 for 19-month weight. Breed direct effects were consistently greatest for C and least for A across all traits, and maternal effects were greatest for S (except for 19-month weight) and least for C. Direct and maternal heterosis, on average, were positive for all weights. The indicus x sanga and indicus x taurus direct heterosis effects on all weight traits were greater than either the taurus x sanga or taurus x taurus effects, whereas the indicus x sanga maternal heterosis effect was consistently less than the estimated taurus x sanga maternal heterosis effect.

Keywords : Direct effects; heterosis; maternal effects; taurus; indicus; sanga.

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