Periodic Measurement of Growth and Carcass Development following Diethylstilbestrol Implantation of Boars

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Abstract
The performance and carcass composition of barrows, boars and boars implanted with 96 mg of diethylstilbestrol (DES) was measured from a liveweight of 70.4 to 1361 kg. Carcass characteristics were related to treatment, age, time of slaughter and carcass weight. Implantation of boars with 96 mg of DES at a liveweight of 70.4 kg increased rate of gain and rate of lean and primal cut deposition. Compared to control boars, the rate of deposition of lean cuts was increased for 10 of the 12 weeks following implantation which coincided with the time during which DES exerted control over sex odor. All boars, regardless of treatment, had carcasses that were significantly longer and leaner and yielded a higher percent lean and primal cuts than littermate barrows of the same weights. A trend for increased area of longis-simus dorsi muscle due to DES treatment of boars was noted. The yield of edible portion and bone of the regular hams from both control and implanted boars was significantly higher and the percent of fat significantly less than in barrows. Measures of growth, such as carcass length and longissimus dorsi muscle, were increased in a linear manner with increasing age and carcass weight, while differences in carcass composition were most directly related to changes in carcass weight. Equation for the linear regression of backfat thickness and weight at a slaughter from 70.4 kg to 136.1 kg were Y = 0.62 + 0.0039X for control boars and Y = 0.26 + 0.0055X for implanted boars.