Heterosis y efectos genéticos en caracteres asociados a la cría en los cruzamientos entre Angus y Hereford

The objective of this work was the evaluation of different variables relevant to breeding. In a diallelic experiment between Hereford (H/H) and Aberdeen Angus (A/A) breeds developed between 1994 and 2002 at the Bernardo Rosengurtt Experimental Station of the Faculty of Agronomy-Udelar, Uruguay, differences in direct genetic effects (gIA-gIH) and maternal genetic effects (gmA-gmH) and maternal genetic effects (gmA-gmH) were estimated, differences in direct genetic effects (gIA-gIH) and maternal genetic effects (gmA-gmH), individual (hIAH) and maternal (hmAH) heterosis effects were estimated by means of linear models for body condition at calving (BCC), birth weight (BW), weaning weight (DW) and inter-calving interval (IPP). For birth weight, neither direct nor maternal additive effects were significantly different. On the other hand, for maternal heterosis, significant differences were observed. In the case of individual heterosis there was a tendency (Pr F=0.09) to be 0.049 kg heavier, in the case of maternal heterosis there was an increase of 0.27± 0.11 kg (P<0.05) in birth weight in HA dams, in the case of weaning weight there were no significant differences for direct individual additive effects between both breeds. Maternal additive effects of AA/AA increased by almost 9.95±4.12 kg weaning weight relative to HH/HH (P<0.05), which is consistent with the results of Alenda et al. (1980) who estimated a value of 4.5 kg for this parameter. The individual heterosis estimated for weaning weight was 2.14±1.07 kg, (P<0.05) For body condition, both individual additive effects and individual heterosis, in spite of finding significant differences in favor of these, they do not take relevance since body condition is discriminated with values not less than 0.25 points; in inter-calving intervals no significant differences were seen either, values of individual additive effects and individual heterosis show that there is no relevance in the genotype used for this characteristic.