Feed Efficiency and Carcass Desirability in Swine

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Abstract
Average daily gain and daily feed consumption, obtained from a total of 185 individually-fed straightbred and crossbred Yorkshire and Duroc pigs, were significantly positively correlated (0.76). Efficiency of feed utilization, expressed as the ratio of average daily gain to average daily feed consumption, was significantly positively correlated (0.24) with gain but negatively correlated (−.54) with feed consumption. The signs and the levels of significance of the relationships of efficiency with gain and feed consumption remained unchanged, when efficiency was expressed as the ratio of gain (either unadjusted or adjusted for initial weight or initial weight and final weight) to feed consumption (adjusted for initial weight or initial weight and final weight). Feed efficiency was also expressed in this study as gain adjusted for feed consumption and as feed consumption adjusted for gain. For both of these estimates of efficiency, feed consumption was adjusted for mid-weight. These two measures were found to yield results that were highly correlated with the estimates of efficiency expressed as the ratio of gain to feed consumption adjusted for mid-weight. The genetic correlations of daily gain with daily feed consumption and efficiency (ratio of gain to feed consumption) were 0.90±0.07 and 0.63±0.26, respectively, and that of efficiency with the feed consumption was 0.20±0.47. Phenotypically, daily gain and feed consumption were negatively associated with percent lean cuts and positively correlated with carcass backfat. Efficiency was positively correlated with percent lean cuts and negatively with carcass backfat. Highly significant genetic correlations were found for carcass backfat with daily gain (1.06) and with daily feed consumption (1.02). A nonsignificant genetic correlation (0.06) was found between backfat and efficiency. The above results indicate that selection for daily gain would probably result in improvement in feed efficiency, as well as in an increase in the amount of backfat. Hence, it would be necessary to consider both backfat and gain in selecting for animals with efficient production of desirable carcasses. Copyright © 1966. American Society of Animal Science . Copyright 1966 by American Society of Animal Science