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Implanting young bulls with zeranol from birth to four slaughter ages: III. Growth performance and endocrine aspects.
J Anim Sci 1986; 63(3):747-56JA

Abstract

Seventy-two Simmental bull calves were assigned randomly either to a zeranol implanted (I) or nonimplanted (NI) control group. Within 3 d after birth, bulls assigned to the I treatment were implanted with 36 mg zeranol and reimplanted every 84 d until slaughter. Calves were weaned at 7.2 mo, preconditioned for 2 wk, and assigned within treatment to slaughter ages 12.0, 13.8, 15.7 and 17.4 mo. Blood samples were taken bimonthly from 8.3 to 16.6 mo of age. Weight gains, feed:gain ratios and slaughter and carcass weights were similar (P greater than .10) for I and NI bulls for the total feeding period. Weight gains for NI bulls were larger (P less than .05) from 7.7 to 9.5 mo and from 11.3 to 12.2 mo of age, whereas gains for I bulls were greater from 12.2 to 14.1 mo. Serum estradiol-17 beta (E2) and testosterone (T) concentrations were higher (P less than .05) for NI bulls at 8.3, 9.2, 10.2, 11.1, 12.1 and 13.0 mo. However, at 13.9 and 14.8 mo, E2 concentrations were higher (P less than .10) for I bulls. A similar, but nonsignificant (P greater than .10), trend was noted for T concentrations of I bulls at 13.9 and 14.8 mo. Rapid increases in E2 concentrations were observed from 8.3 to 9.2 mo in NI bulls, but from 12.1 to 13.9 mo in I bulls. Similarly, T concentrations increased rapidly from 8.3 to 10.2 mo in NI bulls, but from 12.1 to 14.8 mo in I bulls. Peak concentrations of T and E2 for NI bulls were observed near 11 and 13 mo, respectively, whereas peak T and E2 levels were delayed in I bulls until near 14 mo. Periods of greater weight gains for both NI and I bulls corresponded to rapidly increasing E2 and T concentrations. Serum thyroxine concentrations were lower (P less than .05) for I bulls at 13.9 mo but similar to NI bulls at all other ages. Serum insulin concentrations were higher (P less than .05) for I bulls than for NI bulls at 8.3, 10.2, 11.1 and 12.1 mo. Regardless of treatment, insulin concentrations increased with increasing age. Carcasses from I bulls were fatter (P less than .05) and tended (P = .09) to have smaller ribeye areas/100 kg carcass. Fat thicknesses for both treatments increased (P less than .05) from 13.8 to 15.7 mo. Skeletal maturity scores, 9-10-11th rib bone percentages and femur measurements indicated an increased skeletal maturation in I bulls.(

ABSTRACT

TRUNCATED AT 400 WORDS)

Authors

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

Pub Type(s)

Journal Article

Language

eng

PubMed ID

3531136

Citation

Gray, D G., et al. "Implanting Young Bulls With Zeranol From Birth to Four Slaughter Ages: III. Growth Performance and Endocrine Aspects." Journal of Animal Science, vol. 63, no. 3, 1986, pp. 747-56.
Gray DG, Unruh JA, Dikeman ME, et al. Implanting young bulls with zeranol from birth to four slaughter ages: III. Growth performance and endocrine aspects. J Anim Sci. 1986;63(3):747-56.
Gray, D. G., Unruh, J. A., Dikeman, M. E., & Stevenson, J. S. (1986). Implanting young bulls with zeranol from birth to four slaughter ages: III. Growth performance and endocrine aspects. Journal of Animal Science, 63(3), pp. 747-56.
Gray DG, et al. Implanting Young Bulls With Zeranol From Birth to Four Slaughter Ages: III. Growth Performance and Endocrine Aspects. J Anim Sci. 1986;63(3):747-56. PubMed PMID: 3531136.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Implanting young bulls with zeranol from birth to four slaughter ages: III. Growth performance and endocrine aspects. AU - Gray,D G, AU - Unruh,J A, AU - Dikeman,M E, AU - Stevenson,J S, PY - 1986/9/1/pubmed PY - 1986/9/1/medline PY - 1986/9/1/entrez SP - 747 EP - 56 JF - Journal of animal science JO - J. Anim. Sci. VL - 63 IS - 3 N2 - Seventy-two Simmental bull calves were assigned randomly either to a zeranol implanted (I) or nonimplanted (NI) control group. Within 3 d after birth, bulls assigned to the I treatment were implanted with 36 mg zeranol and reimplanted every 84 d until slaughter. Calves were weaned at 7.2 mo, preconditioned for 2 wk, and assigned within treatment to slaughter ages 12.0, 13.8, 15.7 and 17.4 mo. Blood samples were taken bimonthly from 8.3 to 16.6 mo of age. Weight gains, feed:gain ratios and slaughter and carcass weights were similar (P greater than .10) for I and NI bulls for the total feeding period. Weight gains for NI bulls were larger (P less than .05) from 7.7 to 9.5 mo and from 11.3 to 12.2 mo of age, whereas gains for I bulls were greater from 12.2 to 14.1 mo. Serum estradiol-17 beta (E2) and testosterone (T) concentrations were higher (P less than .05) for NI bulls at 8.3, 9.2, 10.2, 11.1, 12.1 and 13.0 mo. However, at 13.9 and 14.8 mo, E2 concentrations were higher (P less than .10) for I bulls. A similar, but nonsignificant (P greater than .10), trend was noted for T concentrations of I bulls at 13.9 and 14.8 mo. Rapid increases in E2 concentrations were observed from 8.3 to 9.2 mo in NI bulls, but from 12.1 to 13.9 mo in I bulls. Similarly, T concentrations increased rapidly from 8.3 to 10.2 mo in NI bulls, but from 12.1 to 14.8 mo in I bulls. Peak concentrations of T and E2 for NI bulls were observed near 11 and 13 mo, respectively, whereas peak T and E2 levels were delayed in I bulls until near 14 mo. Periods of greater weight gains for both NI and I bulls corresponded to rapidly increasing E2 and T concentrations. Serum thyroxine concentrations were lower (P less than .05) for I bulls at 13.9 mo but similar to NI bulls at all other ages. Serum insulin concentrations were higher (P less than .05) for I bulls than for NI bulls at 8.3, 10.2, 11.1 and 12.1 mo. Regardless of treatment, insulin concentrations increased with increasing age. Carcasses from I bulls were fatter (P less than .05) and tended (P = .09) to have smaller ribeye areas/100 kg carcass. Fat thicknesses for both treatments increased (P less than .05) from 13.8 to 15.7 mo. Skeletal maturity scores, 9-10-11th rib bone percentages and femur measurements indicated an increased skeletal maturation in I bulls.(ABSTRACT TRUNCATED AT 400 WORDS) SN - 0021-8812 UR - https://www.unboundmedicine.com/medline/citation/3531136/Implanting_young_bulls_with_zeranol_from_birth_to_four_slaughter_ages:_III__Growth_performance_and_endocrine_aspects_ L2 - https://academic.oup.com/jas/article-lookup/doi/10.2527/jas1986.633747x DB - PRIME DP - Unbound Medicine ER -