Some Effects of Feeding Chlortetracycline upon the Carcass Characteristics and the Body Composition of Swine and a Scheme for the Resolution of the Body Composition

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Abstract
Some of the effects of feeding chlortetracycline upon certain carcass characteristics and the chemical composition of the body of swine were studied. The chlortetracycline-fed pigs gained weight at a slightly more rapid rate than their controls. No significant differences were found between the treatments with respect to the dressing percentage, the proportion of the whole carcass consisting of the wholesale cuts, the actual chemical composition of the carcass meat or the estimated composition of the whole, empty body. As a consequence of the antibiotic-fed pigs weighing slightly more at slaughter time, the average weights of the carcass meat, fat trim and bone from this group were a little greater than those from the control pigs. The specific gravity of the carcass was highly correlated (0.89) with the water content of the carcass. A lower correlation (0.63) was found between the specific gravity of the carcass and the water content of the hole, empty body. During the course of these experiments, a comparison as made between the body water contents of 29 pigs derived by use of the antipyrine-dilution technique and those determined by direct analysis. Within the range (38 to 59 percent) of water contents studied, fairly close agreement was obtained between the results of the two methods. Although the indirect method does not detect small differences in water content, it will provide reliable average results when applied to four or more pigs on a given treatment and when the differences in water content are large. As the result of a study of data published on the body composition of 127 pigs, it was found that the water and fat contents are highly correlated (−0.98) and that the relationship between these two characteristics allows an accurate prediction of the fat content from a knowledge of the water content. The composition of the fat-free body was found to be variable; the fat-free matter of the body varies in water content inversely with the original fat content of the whole animal. The protein and ash contents of the fat-free, dry body were found to be remarkably constant (83.1 ± 1.6 and 16.9 ± 1.6 percent, respectively). Based upon these relationships, a procedure was outlined whereby the total composition of the body of swine can be resolved and the energy value of the body computed from a knowledge of the water content of the whole, empty body. Copyright © . .