Different Protein Levels with and without Antibiotics for Growing-Finishing Swine: Effect on Carcass Leanness

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Abstract
Measurements on length of carcass, specific gravity, percent lean cuts, cross-section area of the loin muscle, live probe, depth of backfat, and weight of leaf fat from 102 swine carcasses are reported in this study. The test rations were fed to the pigs throughout the feeding period without alteration of composition. While there were some discrepancies in the uniformity of response to the imposed experimental treatments in the two experiments in this study, the results are in close agreement. They give no indication that the inclusion of the antibiotics, aureomycin or terramycin, at 5 mg. per lb. of ration in a corn-soybean oil meal ration fed to pigs from weaning to 200 lb. liveweight had an important effect on hog carcass quality. Feeding pigs protein levels over the range from 10 to 20 percent of the ration resulted in carcasses with a significantly greater proportion of lean as the level of protein increased. This increment in proportion of lean per interval of protein (two units percent) increase is of such small magnitude, however, as to be of minor consideration when a choice must be made between two adjacent protein levels. Copyright © . .