Crossbreeding to increase beef production: additive and non-additive effects on weight traits

Abstract

________________________________________________________________________________ AbstractUsing 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 F 1 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. ________________________________________________________________________________

Genetic effects from an Afrikaner, Bonsmara, and Nguni three-breed diallel and top-crosses of Angus and Simmental sires

“…The latter effect is substantially greater than the same effect estimated in the present study. Estimates of average individual heterosis effects on birth weight and 205-day weight from Theunissen et al (2013) were 1.2 and 14.7 kg, respectively, and again the effect on 205-day weight was greater than was observed here. There are multiple plausible explanations for the convergence of direct effects on birth and 205-day weights in the present study.…”

“…The maternal effect of the NG on birth weight and preweaning growth was less than that of the BN and, together with the negative effect on cow weight, indicated the potential for reduced feed intake on the part of the NG cows. In an earlier crossbreeding experiment, which was also conducted at Vaalharts Research Station, Theunissen et al (2013) found the differences between AF and SM direct effects on birth weight and 205-day weight were 1.8 ± 2.8 and 27.3 ± 12.9 kg, respectively. The latter effect is substantially greater than the same effect estimated in the present study.…”

“…Furthermore, exotic breeds such as Angus and Simmentaler may play significant roles as sire lines to increase weights of calves that are produced from indigenous breeds of dam (MacNeil & Matjuda, 2007;Theunissen et al, 2013). Thus, crossbreeding may be valuable to emerging and commercial beef farmers in order to improve the productivity of their herds and economic returns from them.…”

Evaluating Breed Complementarity and Sexed Semen with Maternal Use of Afrikaner Germplasm

“…Carcass data were collected at the Animal and Dairy Research Institute, Irene, South Africa. Thus, parameters for the simulation experiments described hereafter were drawn from previously published literature [18] [24] [25] [26].…”

“…Breed-specific genetic effects, following [30], on the phenotypes used in the simulations for this study were taken from the previously published work of [24] [25] [26]. Specifically, phenotypes were simulated for four breed groups as follows:…”