Five balanced groups with respect to breed, weight and previous management were formed with twenty Holstein and twenty Héreford steers averaging 424 kg and 359 kg, respectively. The groups were randomly assigned to one of the following treatments. 1. Control. 2. Implantation with 36 mg of Zeranol. 3. Implantation with 36 mg of Zeranol and 1,200,000 I.U. of vitamin A, 400,000 I.U. of vitamin D3 and 50 I.U. of vitamin E, inyected intramuscularly on days 1 and 42 of the experimental period. 4. Vitamins ADE as in treatment 3. 5.Implantation with 24 mg of Diethylstilbestrol (DES). The ration fed consisted of red dover silage ad libitum, 100 g of urea and 3 kg of a concentrate mix formed with dried beet pulp 64 percent, oats 32 percent, steamed bone meal 2.6 percent, salt 14 percent. The average daily gains during 101 days were 0.88 kg, 0.90 kg, 0.97 kg, 0.78 kg, 1.10 kg for the treatments 1, 2, 3, 4, and 5 respectively. There was a significant difference (P < 0.05) between the DES and Zeranol effect. Zeranol was 9.1 percent as effective as DES. Zeranol combined with vitamins ADE had an effect equivalent to 40.9 percent of th DES effect. The performance of the groups treated with Zeranol or vitamins ADE alone was not significantly different from the control group. There was also no difference in the cold carcass dressing percent nor in performarice of the two breeds. |
ChileanJAR
