The Effects of Zeranol on the Feedlot Performance of Beef Bulls

Abstract

Prrce, M. A., Me.ranpcnraN, M., TeNNEsseN, T. exo MernrsoN, G. W. 1983

Effects of Zeranol on Weight Gain, Bone Growth and Other Carcass Traits in Steers and Bulls

“…(1970) have reported that zeranol-implanted bulls gain 5-10Vo faster than controls. Zeranol implantation had no effect on backfat thickness, dressing percentage or longissimus dorsi area (Table 1), which is in agreement with previous reports (Greathouse et al 1983;Price et al 1983). …”

“…Scrotal circumference in bulls was not affected by zerano\ which is in agreement with Price et al (1983) (Price et al 1983). It has been suggestedby Wiggins et al (1919) that zeranol implantation would reduce the secretion of thyroid hormones and hence may reduce the metabolic rate and physical activity.…”

“…This contrasts with the study of Price et al (1983) which reported no difference in the libido of zeranol-treated and control bulls. In the present study all of the bulls showed low libido scores but this is normal among such young and inexperienced bulls (Chenoweth 1981).…”

The effect of castration age, method and implant regime on growth and carcass traits of male beef cattle

“…The effect of Ralgro in reducing testicular size has generally been associated with animals implanted at less than 1 yr of age (Silcox et al 1986) although, in some studies (Price et al 1983), this effect has not been apparent.…”

RALGRO® IMPLANTS FOR INTACT MALE CALVES

“…Ralston (1978) Lamm et al (1980) also found that implanting had no effect on daily gain when bulls were implanted at birth and reimplanted every 100 d until slaughter. Price et al (1983) found a substantial (6.l%o), although nonsignificant increase in average daily gain but no effect on feed conversion when crossbred bulls were initially implanted at 5-7 mo of age and reimplanted twice again before slaughter at236 d. In the study by Johnson and Gee ( 1982), either Angus or Gelbviehcrossbred bulls were implanted at the start of a growing phase (92 d) and again at the start of the finishing phase (average of 105 d). Implanting significantly increased average daily gain of the Angus bulls in both the growing and finishing phases but had no effect on the Gelbvieh-crossbred bulls.…”