Sexual Cycle in Sheep Age of puberty is

Sexual Cycle in Sheep • • • Age of puberty is 6 -9 months in sheep. Domestic breeds can be used for breeding starting from 16 -18 months of age but good maintenance and nutrition reduces it to 7 -15 months of age. In sheep, which are among the seasonally polyestric animals, the onset of sexual activity is related to daylight length. The reduction of light exposure with the day length decrease results in increasing the melatonin release from the pineal gland. Increase of blood melatonin level stimulates Gn. RH release from the hypothelamus and the increased Gn. RH release stimulates FSH release by affecting the frontal lobe of hypophysis. FSH travels to the ovaries through blood and initiates follicular developments.

Sexual Cycle in Sheep Sexual cycle in sheep: • • • Proestrus Estrus Metaestrus Diestrus Anestrus (2 -3 days) (30 -36 hours) (2 days) (10 -12 days) (seasonal)

Sexual Cycle in Sheep Proestrus • Lasts 2 -3 days. • is faint. • Outer changes may not be observed.

Sexual Cycle in Sheep Estrus • Lasts 30 -36 hours (depending on ram effect, age and race of sheep, light exposure time) • Ovulation occurs closer to the end of estrus. • Determining the sheep in estrus morning and evening with teaser rams is a necessity. • Behaviour of sheep in estrus is evident when there is a ram and the distinct sign is smelling rams testicles.

Sexual Cycle in Sheep • Detection of estrus by observation is not as easy as it is in cows. • The most distinct sign of sheep in estrus; smelling rams scrotum and standing in front of the ram. • Other than these; restlessness, tail wagging, vulvar swelling and edema, open cervix and sometimes a cervical originated mucous discharge may be observed throughout estrus. • Usage of teaser ram is needed for correct detection of estrus.

Sexual Cycle in Sheep Metaestrus • Lasts 2 days. • Corpus Luteum is active progesterone release is initiated. • Not very important. and

Sexual Cycle in Sheep Diestrus • is the longest phase of the cycle and lasts 10 -12 days. • With the effect of progesterone secreted from Corpus Luteum uterine milk is secreted from the uterine glands and it prepares the uterus for gestation. • If there a viable embryo does not exist by day 13, corpus luteum begins regressing with the effect of PGF 2 secreted from the uterus.

Sexual Cycle in Sheep Anestrus is the sexual rest period of sheep and lasts from mid-winter to mid-summer in the nothern hemisphere.

Sexual Cycle in Goats • • • Goats reach; puberty at approximately 6 -9 months of age and breeding age at 9 -15 months of age. In goats, which are among the seasonally polyestric animals, the onset of sexual activity is related to daylight length. The reduction of light exposure with the day length decrease results in increasing the melatonin release from the pineal gland. Increase of blood melatonin level stimulates Gn. RH release from the hypothelamus and the increased Gn. RH release stimulates FSH release by affecting the frontal lobe of hypophysis. FSH travels to the ovaries through blood and initiates follicular developments.

Sexual Cycle in Goats Sexual cycle phases in goats: • • • Proestrus Estrus Metaestrus Diestrus Anestrus (2 -3 days) (36 -48 hours) (2 days) (14 -16 days) (seasonal)

Sexual Cycle in Goats Proestrus • Lasts approximately 2 -3 days. • is more active when compared to sheep, the buck starts to show interest to the sheep.

Sexual Cycle in Goats Estrus • Lasts approximately 30 -36 hours. • Signs observed; vocalization, restlessness, vulvar swelling, redness, mucous discharge, tail wagging, decrease in apetite, reduction in lactation yield, frequent urination and defecation and smelling genital areas of other goats. • Ovulation occurs closer to the end of estrus, 2 -3 oocytes may be ovulated at once.

Sexual Cycle in Goats Metaestrus • is considered to be the phase in which corpus luteum is formed and lasts approximately 2 days. Diestrus • Lasts approximately 14 -16 days. • In this phase progesterone is released from the corpus luteum and uterus is prepared for gestation. Anestrus • is the sexual rest period for goats and lasts from midwinter to mid-summer in the nothern hemisphere.