An experimental comparison of equivalent terminal and rotational crossbreeding systems in swine: pig performance.

Eleven thousand forty-nine pigs produced from 934 litters using 262 rotational and F1 crossbred sows were used to study differences in pig weights, survival rates and pen average daily gain, daily feed intake, and feed conversion between pigs from equivalent three-breed rotational and three-breed terminal crossbreeding systems using Duroc, Yorkshire, and Landrace breeds. Pig weights at birth and 21 and 56 d and days to reach 100 kg did not differ (P > .10) between the terminal and rotational crossbreeding systems. However, ultrasound backfat thickness of pigs from the terminal crossbreeding system was .04 cm greater (P < .007) than that of pigs from the rotational crossbreeding system. Survival rate from 56 d to 100 kg was .8% greater (P < .01) for pigs from the terminal crossbreeding system than for those from the rotational crossbreeding system. The crossbreeding system had no effect (P > .10) on survival rate at birth, from birth to 21 d, from 21 to 56 d, or from birth to 100 kg. Differences between the two crossbreeding systems were nonsignificant (P > .20) for pen average daily gain, daily feed intake, and feed conversion. Breed composition of pigs was an important source of variation (P < .01) for pig weights at birth and at 56 d. Similarly, breed composition of the pig also affected ultrasound backfat thickness at 100 kg (P < .01), but not days required to reach 100 kg (P > .10). For survival traits, only survival rate from 56 d to 100 kg was influenced by breed composition of the pig.(ABSTRACT TRUNCATED AT 250 WORDS)