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A note on the response to sequential implantation with zeranol
Published online by Cambridge University Press: 02 September 2010
Abstract
Two farm trials were made to investigate the response to a second implant with the anabolic agent zeranol. Seventy cattle were implanted at the start of the growing period, at 10 to 12 months of age, the remaining 49 cattle being left as controls. Five months later, at the beginning of the fattening period, some cattle from each of the treatments during the growing period were implanted. The response to implantation in both periods was significant on both farms (P<0·05). During the fattening period there was no significant difference in the performance of cattle implanted only at the start of the growing period and that of the control animals, which suggested that the response to the earlier implant was permanent. Although differences in performance during fattening for cattle implanted twice, compared with that for cattle implanted for the first time at the start of fattening, were not statistically significant, on both farms performance was lower for the cattle implanted twice. These results suggest that the response to zeranol in the fattening period may be reduced by approximately 0·30 for cattle previously implanted. Over the combined growing and fattening period, cattle implanted twice showed a significant response in comparison with cattle given only one implant (P < 0·05).
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- Copyright © British Society of Animal Science 1982
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