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Sexual development in beef bulls following zeranol implants.
J Anim Sci 1985; 60(2):342-51JA

Abstract

Two trials were conducted to study the effect of zeranol implants on growth and sexual development of bull calves. Trial 1 compared the effects of implanting with 72 mg of zeranol at 48 d of age (branding), at 215 d of age, or at both times with nonimplanted control bulls. Implanting at branding resulted in decreased scrotal circumference, testicle weight and proportion of bulls that could produce an ejaculate at 14 mo of age (P less than .01). Implanting at 215 d of age had no effect on any of these traits. Growth rate was not increased by implanting at either time but was decreased (P less than .02) in animals implanted at both times when compared with control bulls. In trial 2, both bulls and steers were implanted with zeranol and compared with nonimplanted control bulls and steers. Thirty-six-milligram implants were given at 21, 103, 260 and 343 d of age. Scrotal circumference, testicle weight and serum testosterone concentrations decreased (P less than .01) and the occurrence of penis abnormalities increased (P less than .01) in implanted bulls compared with control bulls. By the time of slaughter, however, testosterone concentrations were equal in control and implanted bulls; and the difference in scrotal circumference was diminishing. This is interpreted as evidence that as the bulls get older, they can overcome the effect of the implants. Carcass weights were heavier in implanted steers than in control steers but were lighter in implanted bulls than in control bulls (P less than .02). Carcasses of implanted bulls had higher quality scores and more marbling than control bulls, but carcasses of implanted steers had lower quality scores and less marbling than control steers (both interactions, P less than .01). Implanting bulls with zeranol at an early age resulted in restricted sexual development but not in total sterility. Repeated zeranol implants throughout the growing and finishing phase enhanced carcass quality in bulls slaughtered at 14 to 16 mo of age.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

3988627

Citation

Staigmiller, R B., et al. "Sexual Development in Beef Bulls Following Zeranol Implants." Journal of Animal Science, vol. 60, no. 2, 1985, pp. 342-51.
Staigmiller RB, Brownson RM, Kartchner RJ, et al. Sexual development in beef bulls following zeranol implants. J Anim Sci. 1985;60(2):342-51.
Staigmiller, R. B., Brownson, R. M., Kartchner, R. J., & Williams, J. H. (1985). Sexual development in beef bulls following zeranol implants. Journal of Animal Science, 60(2), pp. 342-51.
Staigmiller RB, et al. Sexual Development in Beef Bulls Following Zeranol Implants. J Anim Sci. 1985;60(2):342-51. PubMed PMID: 3988627.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Sexual development in beef bulls following zeranol implants. AU - Staigmiller,R B, AU - Brownson,R M, AU - Kartchner,R J, AU - Williams,J H, PY - 1985/2/1/pubmed PY - 1985/2/1/medline PY - 1985/2/1/entrez SP - 342 EP - 51 JF - Journal of animal science JO - J. Anim. Sci. VL - 60 IS - 2 N2 - Two trials were conducted to study the effect of zeranol implants on growth and sexual development of bull calves. Trial 1 compared the effects of implanting with 72 mg of zeranol at 48 d of age (branding), at 215 d of age, or at both times with nonimplanted control bulls. Implanting at branding resulted in decreased scrotal circumference, testicle weight and proportion of bulls that could produce an ejaculate at 14 mo of age (P less than .01). Implanting at 215 d of age had no effect on any of these traits. Growth rate was not increased by implanting at either time but was decreased (P less than .02) in animals implanted at both times when compared with control bulls. In trial 2, both bulls and steers were implanted with zeranol and compared with nonimplanted control bulls and steers. Thirty-six-milligram implants were given at 21, 103, 260 and 343 d of age. Scrotal circumference, testicle weight and serum testosterone concentrations decreased (P less than .01) and the occurrence of penis abnormalities increased (P less than .01) in implanted bulls compared with control bulls. By the time of slaughter, however, testosterone concentrations were equal in control and implanted bulls; and the difference in scrotal circumference was diminishing. This is interpreted as evidence that as the bulls get older, they can overcome the effect of the implants. Carcass weights were heavier in implanted steers than in control steers but were lighter in implanted bulls than in control bulls (P less than .02). Carcasses of implanted bulls had higher quality scores and more marbling than control bulls, but carcasses of implanted steers had lower quality scores and less marbling than control steers (both interactions, P less than .01). Implanting bulls with zeranol at an early age resulted in restricted sexual development but not in total sterility. Repeated zeranol implants throughout the growing and finishing phase enhanced carcass quality in bulls slaughtered at 14 to 16 mo of age. SN - 0021-8812 UR - https://www.unboundmedicine.com/medline/citation/3988627/Sexual_development_in_beef_bulls_following_zeranol_implants_ L2 - https://academic.oup.com/jas/article-lookup/doi/10.2527/jas1985.602342x DB - PRIME DP - Unbound Medicine ER -