Efficiency of Gains and Carcass Characteristics of Swine of Two Degrees of Fatness Slaughtered at Three Weights

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Abstract
Two hundred barrows and gilts were slaughtered at 100, 113 and 127 kg live weight. The sample was comprised of 36 litters, of which six litters within each breed of sire (Duroc, Hampshire and Yorkshire) were classified as fat litters (2.36 cm) and six litters classified as lean litters (2.16 cm) on the basis of litter mean backfat probes taken at 68 kg live weight. Growth traits were evaluated from 9 weeks of age until the designated slaughter weight. Carcasses from the first replication (18 litters) were evaluated for percentage separable lean, fat and bone and those from the second replication (18 litters) were evaluated for percentage closely trimmed lean cuts. The fat and lean groups had similar carcass length, longissimus muscle area and percentage closely trimmed lean cuts. The fat group had significantly thicker backfat, lower percentage separable lean and a higher percentage separable fat than the lean group. The three weight groups tended to have similar average daily gains and feed efficiencies for the total test period. As slaughter weight increased from 100 to 127 kg there was an increase in carcass backfat thickness (P<.05) and longissimus muscle area (P<.01). Percentage separable lean, fat and bone of carcass were similar at each of the three slaughter weights. The 127 kg group tended to have lower percentages closely trimmed lean cuts than the 100 and 113 kg groups which had similar percentages. The effect of slaughter weight on growth and carcass traits in this study differ from findings reported earlier for swine of different genetic background. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.