Hormones are chemical substances which co-ordinate the activities of the body. They are secreted by ductless glands in the body and transferred through the blood to the target organs on which they exert their effects. Hormones . concerned with reproduction in farm animals can be grouped into male and female reproductive hormones.
Male Reproductive Hormones
1) Androgen (Testosterone)
- It initiates spermatogenesis (sperm formation).
- It is responsible for the initiation of male secondary sex characteristics.
- Maintains the sex drive (libido).
- Enhances muscular and skeletal growth.
- Reduces fat deposition.
- Promotes the growth of accessory sex glands.
- Sustains the life of sperms in the epididymis.
Female Reproductive Hormones
- Stimulates the development of female secondary sex characteristics e.g. heat behaviour.
- Promotes the production of eggs through oogenesis.
- It is concerned with the preparation of the uterus lining for the reception of the fertilized ovum.
- It increases blood supply as well as the water content of the uterus.
- It stimulates the growth of the duct system in the mammary glands (udder).
- In the oviduct, it increases cilliary activities and mucous secretion.
- Induces the rapid multiplication of epithelum in the vagina.
3) Follicle Stimulating Hormone (FSH)
- It stimulates the growth of the ovarian follicle.
4) Luteinizing Hormone (LH)
- It causes the rupture of the follicle and subsequent release of ova (i.e ovulation).
- It stimulates the secretion of ovarian hormones i.e. oestrogen and progesterone.
5) Progesterone (Pregnancy hormone)
- It ensures the development of uterus and implantation of the fertilised ovum.
- It inhibits oestrus (i.e it prevents the ripening of more follicles).
- It causes the development of alveoli in mammary gland.
- It ensures the continuance of pregnancy.
- It aids in the contraction of the female uterine muscles during pregnancy.
- It affects mammary gland after birth by causing milk let-down or milk production ..
- It promotes the transport of spermatozoa in the female genital tract.
- It causes the relaxation of the pelvic ligament during parturition for easy passage of the young ones.