Early growth performance of Bos taurus x Bos indicus cattle crosses in Ethiopia:: Evaluation of different crossbreeding models

Five genetic models were evaluated for goodness-of-fit and estimation of crossbreeding parameters using 41 genotypes produced from crossing three Bos taurus (Friesian, Jersey and Simmental) with three Bos indicus (Boran, Barca and Horro) breeds. The traits used for testing of the models were birth weight, weaning weight, pre-weaning-average daily gain and yearling weight. These models were: (1) Dominance model, (2) Dickerson's model (recombination loss) (3) Additive x dominance interaction model, (4) Dominance x dominance interaction model and (5) Kinghorn's model (x). Models 2-5 are epistatic models that included all effects in model one plus one type of epistatic interaction based on a two-locus gene model. All five models tested, provided high levels of fit, with adjusted R (2) values averaging 93% over traits. All the epistatic models fit the data significantly (p < 0.05) better than the dominance model for all the traits. Among the epistatic models, Dickerson's model (M2) gave significantly (p < 0.05) higher R (2) values compared with the other epistatic models. Crossbreeding parameters estimated from this model have relatively lower sampling correlations and correspondingly lower standard errors. This model could, therefore, be considered the most appropriate model for parameter estimation and prediction-of performance of untested genotypes for future breeding decision for breeds involved in this study.