Some Carcass Characteristics of Swine in the Eighth Generation of Production under Four Combinations of Full and Limited Feeding

Abstract

Thirty-two gilts, from the eighth generation of an experiment designed to study the relationship between nutrition and improvement of animals for meat production through breeding were slaughtered to study carcass characteristics under four combinations of full and limited feeding. The gilts selected from a background of full feeding showed more muscling than those selected from a background of limited feeding. The measure was the area of cross section of the longissimus dorsi muscle. Gilts from the background of full feeding averaged over ½ sq. in. greater development of loin eye (P<0.01). The results of this study indicate that a better job of selection for meat-type hogs, as based on muscular development, can be accomplished under full feeding, where the muscling is allowed to express itself to the fullest extent by selection time. The plane of nutrition had a statistically significant effect upon carcass fatback (P<0.01). The full-fed gilts averaged 0.32 in. more backfat than gilts receiving 70% of full feed. When the 56.5 days difference in age between the two groups at slaughter was adjusted to a constant age, the full-fed gilts averaged 0.56 inch more backfat than the limited-fed gilts. There was a statistically significant interaction between selection background and plane of nutrition On yield of trimmed primal cuts. Selection under full feeding favored a higher yield of trimmed primal cuts when such animals were placed on limited feeding. This genotype-environment interaction may partly determine whether breeding stock should be selected under the environment in which their progeny will be produced. A highly significant correlation between live backfat probes and carcass fatback measurements was found.