GROWTH, FEED EFFICIENCY AND GROSS CHEMICAL COMPOSITION IN MARKET-WEIGHT PIGS AS INFLUENCED BY A COMBINATION OF SYNTHETIC SEX HORMONES AND TYLOSES

Abstract

A combination of diethylstilbestrol + methyltestosterone + Tylosin, added to a balanced ration during the finishing period, resulted in a trend towards increased gains, improved feed efficiency and a reduction in age to market of 5 to 6 days in both barrows and gilts. Carcass measurements were not significantly different between control and treated groups within sex, but there was a tendency toward a reduction in carcass fat measurements in the treated barrows (which brought these values down to the levels of the control gilts) and an increase in the treated gilts. The chemical composition of the carcass and the major cuts showed a significant reduction in fat and a significant increase in protein in the treated barrows. The effect of treatment on the carcasses of the gilts was not significant, but there was a tendency toward an increase in fat deposition. In the barrows, treatment resulted in a differential growth of protein and fat in the major cuts, the ham and loin (but not the shoulder and belly), showing a significant increase in protein, while fat decreased in all cuts of the treated barrows.It was suggested that different proportions of sex steroid hormones would be required for barrows and gilts to achieve beneficial effects on carcass composition.