Estimation of genetic and crossbreeding parameters for preweaning traits in German Angus and Simmental beef cattle and the reciprocal crosses.

Data from pure breeds, as well as reciprocal crosses of German Angus (GA) and Simmental (SIM) beef cattle, were used to estimate genetic parameters and to evaluate the suitability for crossbreeding in terms of increasing productivity. Traits of interest were calving difficulty, birth weight (BWT), weaning weight (WWT), and ADG from birth to weaning. Data were collected over a period of 7 yr from 1997 and 1998 until 2003 and 2004, whereas crossbreeding was carried out in 2002 and 2003, and 2003 and 2004 only. Variance components and differences between breeds, individual heterosis, and maternal breed effects were analyzed based on 1,441 purebred and 329 crossbred records for BWT and 1,319 purebred and 316 crossbred records for WWT and ADG, respectively. Mean calving difficulty scores were greater in SIM than in GA (P < 0.001). For BWT, WWT, and ADG both reciprocal crosses fell between the purebreds, and for all 3 traits SIM showed greater average values compared with GA. The estimated heritabilities were 0.23 for BWT and 0.12 for WWT. Values for the maternal effect and the correlation between additive and maternal effect were 0.18 for BWT, 0.08 for WWT, 0.32 for BWT, and 0.50 for WWT, respectively. Individual heterosis was only significant for BWT (3.7%; P < 0.01). Superior mothering ability of SIM was implicated by greater WWT and ADG of SIM as dam against the reciprocal cross (P < 0.001). The results provide information about the extent of individual heterosis and maternal breed effects.