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Effect of nutrition during calfhood and peripubertal period on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls.
Domest Anim Endocrinol 2007; 33(1):1-18DA

Abstract

The objective of the present study was to characterize the effects of nutrition on circulating concentrations of metabolic hormones, gonadotropins, and testosterone during sexual development in bulls. Nutrition regulated the hypothalamus-pituitary-testes axis through effects on the GnRH pulse generator in the hypothalamus and through direct effects on the testes. Pituitary function (gonadotropin secretion after GnRH challenge) was not affected by nutrition. However, nutrition affected LH pulse frequency and basal LH concentration during the early gonadotropin rise (10-26 weeks of age). There were close temporal associations between changes in insulin-like growth factor-I (IGF-I) concentrations and changes in LH pulse frequency, suggesting a role for IGF-I in regulating the early gonadotropin rise in bulls. The peripubertal increase in testosterone concentration was delayed in bulls with lesser serum IGF-I concentrations (low nutrition), suggesting a role for IGF-I in regulating Leydig cell function. Serum IGF-I concentrations accounted for 72 and 67% of the variation in scrotal circumference and paired-testes volume, respectively (at any given age), indicating that IGF-I may regulate testicular growth. Bulls with a more sustained elevated LH pulse frequency during the early gonadotropin rise (high nutrition) had greater testicular mass at 70 weeks of age relative to the control group (medium nutrition), despite no differences in metabolic hormone concentrations after 26 weeks of age. Therefore, gonadotropin-independent mechanism regulating testicular growth might be dependent on previous gonadotropin milieu.

Authors+Show Affiliations

Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr., Saskatoon, Sask., Canada S7H 4B5. lfcbrito@lycos.comNo affiliation info availableNo affiliation info availableNo 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

16677793

Citation

Brito, Leonardo F C., et al. "Effect of Nutrition During Calfhood and Peripubertal Period On Serum Metabolic Hormones, Gonadotropins and Testosterone Concentrations, and On Sexual Development in Bulls." Domestic Animal Endocrinology, vol. 33, no. 1, 2007, pp. 1-18.
Brito LF, Barth AD, Rawlings NC, et al. Effect of nutrition during calfhood and peripubertal period on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls. Domest Anim Endocrinol. 2007;33(1):1-18.
Brito, L. F., Barth, A. D., Rawlings, N. C., Wilde, R. E., Crews, D. H., Mir, P. S., & Kastelic, J. P. (2007). Effect of nutrition during calfhood and peripubertal period on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls. Domestic Animal Endocrinology, 33(1), pp. 1-18.
Brito LF, et al. Effect of Nutrition During Calfhood and Peripubertal Period On Serum Metabolic Hormones, Gonadotropins and Testosterone Concentrations, and On Sexual Development in Bulls. Domest Anim Endocrinol. 2007;33(1):1-18. PubMed PMID: 16677793.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of nutrition during calfhood and peripubertal period on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls. AU - Brito,Leonardo F C, AU - Barth,Albert D, AU - Rawlings,Norm C, AU - Wilde,Randal E, AU - Crews,Denny H,Jr AU - Mir,Priya S, AU - Kastelic,John P, Y1 - 2006/04/21/ PY - 2006/02/11/received PY - 2006/03/31/revised PY - 2006/04/03/accepted PY - 2006/5/9/pubmed PY - 2007/7/20/medline PY - 2006/5/9/entrez SP - 1 EP - 18 JF - Domestic animal endocrinology JO - Domest. Anim. Endocrinol. VL - 33 IS - 1 N2 - The objective of the present study was to characterize the effects of nutrition on circulating concentrations of metabolic hormones, gonadotropins, and testosterone during sexual development in bulls. Nutrition regulated the hypothalamus-pituitary-testes axis through effects on the GnRH pulse generator in the hypothalamus and through direct effects on the testes. Pituitary function (gonadotropin secretion after GnRH challenge) was not affected by nutrition. However, nutrition affected LH pulse frequency and basal LH concentration during the early gonadotropin rise (10-26 weeks of age). There were close temporal associations between changes in insulin-like growth factor-I (IGF-I) concentrations and changes in LH pulse frequency, suggesting a role for IGF-I in regulating the early gonadotropin rise in bulls. The peripubertal increase in testosterone concentration was delayed in bulls with lesser serum IGF-I concentrations (low nutrition), suggesting a role for IGF-I in regulating Leydig cell function. Serum IGF-I concentrations accounted for 72 and 67% of the variation in scrotal circumference and paired-testes volume, respectively (at any given age), indicating that IGF-I may regulate testicular growth. Bulls with a more sustained elevated LH pulse frequency during the early gonadotropin rise (high nutrition) had greater testicular mass at 70 weeks of age relative to the control group (medium nutrition), despite no differences in metabolic hormone concentrations after 26 weeks of age. Therefore, gonadotropin-independent mechanism regulating testicular growth might be dependent on previous gonadotropin milieu. SN - 0739-7240 UR - https://www.unboundmedicine.com/medline/citation/16677793/Effect_of_nutrition_during_calfhood_and_peripubertal_period_on_serum_metabolic_hormones_gonadotropins_and_testosterone_concentrations_and_on_sexual_development_in_bulls_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0739-7240(06)00044-0 DB - PRIME DP - Unbound Medicine ER -