Reproductive Hormones Copyright PEER.tamu.edu

 A hormone is a chemical released into the blood and transported to affect cells in other parts of the body.  Hormones regulate many things in the body, such as:  Growth and development.  Male and female sexual development.  How the body uses energy.  Levels of salts and sugars in the blood.  The amount (volume) of fluid in the body. Charolais Cattle

 Certain hormones play key roles in reproduction.  They cause different sexual characteristics in males and females and control fertility or the ability to have offspring.  There are several reproductive hormones but the two major ones are Estrogen and Testosterone.

 Puberty is the process of physical changes by which a animal’s body becomes an adult body capable of reproduction.  Puberty is initiated by hormone signals from the brain via the pituitary gland to the ovaries of the females and testes of the males. In response, these organs produce a variety of hormones that stimulate the growth, function, or transformation of brain, bones, muscle, skin, mammary glands, and reproductive organs. A mature wild stallion and a young male colt

Boer Goat Quarter HorseDuroc Pig

 Estrogens are hormones found in females and in low levels in males.  These hormones control different stages of the reproductive cycle in females.  In females, estrogens control the development of secondary sex characteristics.  In males and females estrogen promotes normal bone development.  In females, estrogen is produced by the ovaries. A Jersey cow showing definite female secondary sex characteristics including udder (mammary glands), light muscling in neck and hindquarters, and smaller and more delicate head and jowls.

 Testosterone, like estrogen, is also a steroid hormone. It is found in males and in smaller amounts in females.  Testosterone in males is produced by the testicles. A Grand Champion Romney ram

 In males, testosterone controls the development of male reproductive organs and secondary sex characteristics such as increased muscle mass.  Testosterone is important in bone mass development as well as the prevention of osteoporosis  Testosterone is also responsible for the libido or sex drive of the male. Welsh Cob

Compare and contrast the characteristics of these male animals to the females you observed earlier.