Sexual Maturity and the Estrous Cycle Ms Sears

Sexual Maturity and the Estrous Cycle Ms. Sears

Sexual Maturity • Horses reach maturity between 12 to 18 months • They should be separated around this age to prevent accidental breeding

Sexual Maturity cont. • Waiting to breed horses until they are 3 yrs. old is recommended

Estrous Cycle • Estrous – Heat cycle • Estrus – signs of standing heat • Anestrus – not in heat (typically in winter)

Estrous Cycle cont. • 4 stages • Proestrus • Estrus • Metestrus • Diestrus

Proestrus • Follicles develop • Estrogen levels rise

Estrus • Estrogen levels are high • Females are ready to breed ( in standing heat) • Lasts 12 hrs to a few days

Metestrus • Estrogen decreases • Progesterone is produced

Diestrus • If pregnant : progesterone stays high • If not : progesterone decreases and prostaglandin increases

Estrus Detection • Change in behavior • Squeal, kick, bite, raised tail, squatting, and frequent urination. • Lasts 12 hrs. to a few days

Estrous Cycle • Horses are seasonal breeders. • Long day breeders • Mares ovulate every 21 days during the breeding season

Female Hormones • FSH – stimulates follicle • LH – Triggers ovulation • Estrogen – Prepares for pregnancy • Progesterone – maintains pregnancy • Prostaglandin – induces labor

Male Hormones • Testosterone – Causes male breeding behavior, promotes growth and the development and function of accessory sex glands • FSH – stimulates sperm production • LH – needed for completing sperm production