CHLORTETRACYCLINE AND PROTEIN LEVEL IN RATIONS FOR MARKET HOGS: II. EFFECT ON CARCASS QUALITY

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Abstract
Three trials, with a total of 20 pigs on each of eight treatments, were conducted to determine the effect, on carcass quality of Yorkshire pigs, of self-feeding rations of low, medium, standard, and high protein content, with and without chlortetracycline (aureomycin), from weaning to market weight. The approximate protein levels were 13, 15, 17, and 19 per cent from weaning to 70 lb.; 12, 13.5, 14.5, and 15.5 per cent from 70 to 130 lb.; and 11, 12, 12.5, and 13 per cent from 130 to 200 lb.Aureomycin had no significant effect on length of carcass, or on the area of the eye of lean, at any of the four levels of protein tested. Aureomycin significantly increased the depth of backfat, but not shoulder or loin fat, at all protein levels. With the type of pigs used this increase did not have any adverse effect on grades.Protein level had no significant effect on length of carcass, depth of shoulder fat, or depth of backfat. As protein level increased, increases in the area of the eye of lean occurred.