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By: A. Riasi (PhD in Animal Nutrition & Physiology) riasi.iut.ac.ir

Isfahan University of Technology, Isfahan, Iran. Advanced Reproductive Physiology (part 1). By: A. Riasi (PhD in Animal Nutrition & Physiology) http://riasi.iut.ac.ir. The topics. Puberty and sexual maturity Physiology of gamete production

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By: A. Riasi (PhD in Animal Nutrition & Physiology) riasi.iut.ac.ir

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  1. Isfahan University of Technology, Isfahan, Iran Advanced Reproductive Physiology (part 1) By: A. Riasi (PhD in Animal Nutrition & Physiology) http://riasi.iut.ac.ir

  2. The topics • Puberty and sexual maturity • Physiology of gamete production • Hormonal & non-hormonal secretions of reproductive in male and female animals • Physiology of pregnancy and embryo development

  3. The topics (continue) • Physiology of parturition • Pheromones • Abnormality of reproduction • Reproductive immunology • Recent advance associated with reproductive physiology

  4. References • Pathways to Pregnancy and Parturition, P.L. Senger, Second edition, 2011. • Reproductive in Farm Animals, By: E.S.E. Hafez, 2000. • Improving the Reproductive Management of Dairy Cattle Subjected to Artificial Insemination, By: IAEA-TECDOC-1533, 2007. • Review and original papers

  5. Puberty and sexual maturity • What is the difference between puberty and sexual maturity?

  6. Puberty and sexual maturity • Definition of puberty in females: • Age at first estrus • Age at first ovulation • Age at which a female can support pregnancy without deleterious effects.

  7. Puberty and sexual maturity • Definition of puberty in males: • Age when behavioral traits are expressed. • Age at first ejaculation. • Age when spermatozoa first appear in the ejaculate. • Age when spermatozoa first appear in the urine. • Age when the ejaculate contains a threshold number of spermatozoa.

  8. Puberty and sexual maturity • Hypothalamus controls puberty in animals • Two centers in hypothalamus: • Tonic center • Surge center

  9. Puberty Surge Surge Tonic Tonic

  10. Puberty

  11. Puberty Adapted from Vasantha SKI and Kona SSR. 2016

  12. Puberty

  13. Effect of testosterone on male brain T Testis T E2 Blood Brain Barrier Surge Center Does not Develop

  14. Effect of estrogen on female brain aFP + E2 E2 Placenta E2 E2 E2 Ovary Blood Brain Barrier Surge Center Develops

  15. Average age of puberty (range) Species Male Female Bovine 11 mo (7-18) 11 mo (9-24) Ovine 7 mo (6-9) 7 mo (4-14) Porcine 7 mo (5-8) 6 mo (5-7) Equine 14 mo (10-24) 18 mo (12-19) Human 13 yr 12 yr

  16. Factors affecting puberty • Puberty may affected by different factors: • Heritability and breed • Environmental factors • Heat stress, birth month, photoperiod, social condition • Nutrition • Weight and growth rate • Endocrine factors

  17. Influence of Growth Rate and Bull Exposure on Age of Puberty 500 449 428 422 400 375 High Growth Rate Moderate Growth Rate 300 Age at Puberty (days) 200 100 0 Heifers only Bull Exposure

  18. Nutrition affect puberty Adapted from Vasantha SKI and Kona SSR. 2016

  19. Nutrition affect puberty Association of weight:height ratio (W:H) and age at puberty (AP) in crossbred beef heifers. (Adapted from Bras., 2017)

  20. Role of leptin in puberty • Effect of a minimum percentage of body fat • Serum leptin concentrations • Leptin does not serve as triggering signal • Leptin acts mainly as a permissive signal that permits puberty to occur • Proopiomelanocortin system affect leptin role in GnRH neuron activation

  21. Role of leptin in puberty Model for pathways mediating the nutritional regulation of GnRH release during pubertal development. (Adapted from Marcel Amstalden et al., 2011).

  22. Nutrition affect puberty Association of fat thickness (FAT) and age at puberty (AP) in crossbred beef heifers.(Adapted from Bras., 2017)

  23. Role of insulin in puberty • The role of insulin in setting pace for the pubertal onset by monitoring the nutritional status was proposed and its role through IGF-I.

  24. Role of NPY in puberty • The role of NPY in the inhibition of GnRH and subsequent LH release was proposed. • This was correlated with a fastened puberty in calves whose metabolic status was favorable with increased leptin and decreased NPY levels.

  25. Role of melatonin in puberty • Pineal gland activity and melatonin secretion is dependent on the photoperiod. • There were few studies depicting its direct role in pubertal development.

  26. Some research papers associated to this lecture Barb, C. R. and R.R. Kraeling. 2004. Role of leptin in the regulation of gonadotropin secretion in farm animals. Anim. Reprod. Sci. 82–83: 155–167. Clarke, I. J. and B. A. Henry. 1999. Leptin and reproduction. Reviews of Reprod. 4: 48–55. Vasantha SKI and Kona SSR. 2016. Physiology of puberty in females: A review. Int. J. Vet. Sci. Anim. Husbandry. 1(2): 23-26.

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