Veterinary Andrology and Reproductive Techniques

INTRODUCTION

• The reproductive behavior in animals is innate in nature.
• It is an obligatory component of reproductive process.
• The purpose of reproductive behavior is to promote the opportunity of copulation and thereby pregnancy will occur and the birth of young one.
• This behavior involves series of endocrine and neural events.
• When the males attain puberty their behavior becomes more insistent towards opposite sex.
• As the bulls mature the manifestation of sexual behavior become evident.
• The pituitary gland secretes the gonadotrophic hormones follicle stimulating hormone (FSH) – maintains seminiferous tubules and initiates spermatogenesis and luteinizing hormone (LH) - produces androgenic hormone – testosterone which is responsible for sexual behavior and secondary sexual characters.
• The male animal exhibits the sexual activity occurs at any time whereas in females it is restricted only during the time of estrum.
• During embryogenesis, sexual differentiation occurs and the brain is programmed ad either male or female. In the female fetus a small quantity of estradiol is secreted.
• From the fetal liver the α-fetoprotein is produced.
• The estradiol will combine with α-fetoprotein which prevents its entry into brain by crossing blood brain barrier.
• So the surge and tonic centers of brain are not affected and the animal will be fully feminized.
• So the female will exhibit the estrual behaviors only during estrum.
• In the male fetus a small quantity of testosterone is produced which will bind with the α-fetoprotein secreted in liver, crosses blood brain barrier and reaches brain.
• In the brain it converted into estradiol and causes defeminization and musculinization of the brain by affecting surge center.
• Due to this the male animals exhibit estrual behavior at any time.

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