POSTWEANING PERFORMANCE AND CARCASS MERIT OF PUREBRED AND TWO-BREED CROSS PIGS

The feedlot records of 2,111 purebred and crossbred pigs representing all purebred and all possible two-way crosses of Duroc, Hampshire and Yorkshire were analyzed to evaluate average daily gain on test, age at 100 kg, average backfat probe of gilts, average daily feed consumption and feed conversion. A random sample of 392 barrows was used to evaluate carcass traits. The data were analyzed to determine breed of sire and breed of dam effects, to evaluate differences between reciprocal crosses and to estimate heterosis. Breed of sire and breed of dam effects were significant for many of the traits evaluated. Straightbred Durocs had a higher average daily gain, were fatter and produced carcasses that were firmer and had more marbling than straightbred Hampshires or Yorkshires (P\u3c.05). Yorkshires were the most efficient straightbred while Hampshires had the largest longissimus muscle areas and leanest carcasses of the straightbreds. Significant differences were noted between reciprocal crosses. When Yorkshires were involved in the cross, the pigs were more efficient, consumed less feed per day and produced carcasses that were leaner and had larger longissimus muscle areas when the Yorkshire was used as the dam rather than as the sire (P\u3c.05). Significant and favorable heterosis was found for average daily gain, age at 100 kg, feed efficiency, feed consumption and carcass length when averaged over all crosses. The general lack of heterosis for carcass traits indicates that the carcass merit of crossbred pigs can be approximated by the average of the purebreds involved in the cross