Comparisons of Specific Crosses
نویسنده
چکیده
Specific crosses resulting in 305 litters sired by Duroc, Spot or Hampshire boars out of Landrace, Duroc-Landrace or YorkshireLandrace sows were evaluated for preweaning and postweaning performance. Duroc-sired litters were heavier (P<.05) at 21 days postfarrowing than Spotor Hampshiresired litters. Hampshire-sired litters were heavier (P<.05) at birth than Spot-s i red litters. Litters from crossbred sows were larger in number (P<.05) and heavier at 21 (P<.01) and 42 days (P<.05) than those from Landrace sows. However, survival rate to weaning did not differ significantly between the litters from crossbred and from purebred females. There were no significant differences in lit ter size between Duroc-Landrace and YorkshireLandrace sows. However, pigs out of DurocLandrace sows were heavier (P<.01) at birth than pigs out of Yorkshire-Landrace sows. The interactions of the Spot and Hampshire sire breeds with the Landrace and crossbred Landrace dam breeds were significant for lit ter size at 21 and 42 days and for survival rate. A change in the rankings for these traits was noted. Pig weights at 21 and 42 days showed the same interaction. Maximum preweaning performance resulted from the mating of Duroc boars to Duroc-Landrace or Yorkshire-Landrace sows or of Hampshire boars to Duroc-Landrace sows. No significant differences among the sire breeds were noted in progeny postweaning daily gain or days to 100 kilograms. Pigs out of Duroc-Landrace sows had higher postweaning gains (P<.10)
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