The effects of the rate of gain during four periods of growth on carcass characteristics in swine
Ho, Robert S.
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Records of 176 Hampshire pigs, consisting of 118 barrows and 58 gilts, were used in this study. The least squares method was applied to estimate the effect of rate of gain during four periods of growth (birth to 50 pounds, 50 to 100 pounds, 100 to 150 pounds, and 150 to 200 pounds) on carcass characteristics. The results were expressed as partial regression coefficients in terms of square inches or inches per pound for deviation in growth rate. The loin eye area and the average back fat thickness had a consistent, but not statistically significant association with the live weight groupings as arbitrarily designation. The carcass length was inconsistently and statistically nonsignificantly related to the live weight. Sex of the animal did effect the carcass in that gilts had leaner carcasses than barrows as shown by larger loin eye areas and thinner back fat. When the average daily gain increased one pound during 100 to 150 pound growing period, the loin eye area was 0.40 square inches larger at a slaughter weight of 200 pounds. When the average daily gain increased one pound during the suckling period, the average back fat was 0.25 inches thinner at 200 pounds. As the daily gain increased one pound during the second growing period, the average back fat was 0.15 inches thicker in the finished pigs. The growth rate had a statistically nonsignificant effect on the carcass length during any period of growth. The growth rate during period other than those shown had no effect on the carcass characteristics measured in this study.
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