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Effect of zeranol on sexual development of crossbred bulls.
J Anim Sci 1989; 67(7):1751-6JA

Abstract

Three groups of 1/2 Simmental X 1/4 Brahman X 1/4 Hereford bull calves were used during two different years to study effects of zeranol on sexual development. At 154 d of age, half the calves were implanted with 36 mg zeranol and half, not implanted, served as controls. Implanted calves were reimplanted at 90-d intervals throughout the trial (9 mo) each year. Trial 1 was conducted with 24 calves and Trial 2 was conducted the following year with 10 bulls. Twenty-four days after weaning (200 d of age) and at 28-d intervals thereafter, bulls in drylot in Trial 1 were weighted, scrotal circumference (SC) was measured and an ejaculate of semen was collected by electroejaculation to determine puberty. At these times, bulls were given 200 micrograms of GnRH i.m. and blood was collected at 0, 1, 2, 3, 4 and 5 h after GnRH. Serum concentrations of LH and testosterone (TEST) were determined. At slaughter, testis weight, length and circumference and pubertal status were recorded. Bulls implanted with zeranol had smaller SC than control bulls during the entire 9-mo period (P less than .0001). More control bulls reached puberty than did implanted bulls (82.4 vs 23.5%, respectively; P less than .001). Control bulls had larger testis measurements at slaughter (P less than .0001). Implants did not alter total weight gain or ADG (P greater than .10).(

ABSTRACT

TRUNCATED AT 250 WORDS)

Authors+Show Affiliations

Texas A&M University Agricultural Research and Extension Center, Overton 75684.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

2768123

Citation

Godfrey, R W., et al. "Effect of Zeranol On Sexual Development of Crossbred Bulls." Journal of Animal Science, vol. 67, no. 7, 1989, pp. 1751-6.
Godfrey RW, Randel RD, Rouquette FM. Effect of zeranol on sexual development of crossbred bulls. J Anim Sci. 1989;67(7):1751-6.
Godfrey, R. W., Randel, R. D., & Rouquette, F. M. (1989). Effect of zeranol on sexual development of crossbred bulls. Journal of Animal Science, 67(7), pp. 1751-6.
Godfrey RW, Randel RD, Rouquette FM. Effect of Zeranol On Sexual Development of Crossbred Bulls. J Anim Sci. 1989;67(7):1751-6. PubMed PMID: 2768123.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of zeranol on sexual development of crossbred bulls. AU - Godfrey,R W, AU - Randel,R D, AU - Rouquette,F M,Jr PY - 1989/7/1/pubmed PY - 2001/3/28/medline PY - 1989/7/1/entrez SP - 1751 EP - 6 JF - Journal of animal science JO - J. Anim. Sci. VL - 67 IS - 7 N2 - Three groups of 1/2 Simmental X 1/4 Brahman X 1/4 Hereford bull calves were used during two different years to study effects of zeranol on sexual development. At 154 d of age, half the calves were implanted with 36 mg zeranol and half, not implanted, served as controls. Implanted calves were reimplanted at 90-d intervals throughout the trial (9 mo) each year. Trial 1 was conducted with 24 calves and Trial 2 was conducted the following year with 10 bulls. Twenty-four days after weaning (200 d of age) and at 28-d intervals thereafter, bulls in drylot in Trial 1 were weighted, scrotal circumference (SC) was measured and an ejaculate of semen was collected by electroejaculation to determine puberty. At these times, bulls were given 200 micrograms of GnRH i.m. and blood was collected at 0, 1, 2, 3, 4 and 5 h after GnRH. Serum concentrations of LH and testosterone (TEST) were determined. At slaughter, testis weight, length and circumference and pubertal status were recorded. Bulls implanted with zeranol had smaller SC than control bulls during the entire 9-mo period (P less than .0001). More control bulls reached puberty than did implanted bulls (82.4 vs 23.5%, respectively; P less than .001). Control bulls had larger testis measurements at slaughter (P less than .0001). Implants did not alter total weight gain or ADG (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS) SN - 0021-8812 UR - https://www.unboundmedicine.com/medline/citation/2768123/Effect_of_zeranol_on_sexual_development_of_crossbred_bulls_ L2 - https://academic.oup.com/jas/article-lookup/doi/10.2527/jas1989.6771751x DB - PRIME DP - Unbound Medicine ER -