1. The Effect of Hormones on the Estrous Cycle
Hypothalmus- primitive part of the brain that controls other endocrine glands. Stimulates the pituitary
Pituitary Gland –at the base of the brain. Regulates hormone secretion throughout the body.
FSH – Follicle Stimulating Hormone. Causes the follicle to mature.
Lutenizing Hormone – causes ovulation and the formation of the corpus luteum.

2. Hormones Estrogen- Prepares the cow for sexual activity. “Heat”
Progesterone,
secreted by the corpora lutea,
Stops the development of follicles
Stops estrogen.
Stops cow from coming into heat.
prepares the uterus to receive the fertilized egg maintains pregnancy.
Follicle stimulating hormone (FSH) and luteninizing hormone (LH) are secreted & travel through the blood to the ovary.
FSH and LH are mediated by gonadotropic releasing hormone (GnRH) coming from the hypothalamus to signal their release from the pituitary.
FSH stimulates the growth, development and function of the follicle, while LH cause the follicle to rupture during ovulation and causes the subsequent development of the corpus luteum.
Hormones

3. Two organs of reproduction are located in the head
hypothalamus controls:
Body temperature, and the drive to eat and drink are just a few functions.
It sends and receives neural signals through the nervous system and hormonal messages through the endocrine system.
pituitary gland, at the base of the brain.
The pituitary is divided into two regions: the anterior and posterior pituitaries.

4. We are going to look into the function of the hypothalamus and the pituitary gland.

5. Follicle produced by FSH

6. This follicle will soon rupture(ovulation) with the help of LH

7. CL (Corpus Luteum) takes the place of the follicle
CL (Corpus Luteum) takes the place of the follicle. The CL produces the hormone progesterone.

8. Estrous
Heat is the time when a female is receptive to the male and will allow breeding to take place
Heat is actually divided into 4 phases of the cycle.

9. Phases of Estrous Proestrus: ovary is about to release an egg
Estrus: female receptivity
Metestrus: uterus prepares for pregnancy
fertilized egg attaches to uterus
Diestrus: longest period of cycle
inactive
Estrous Cycles stop after conception, and begin soon after Parturition (birth)

10. Hormones Estrogen – produced by the ovary
causes secondary sexual characteristics to develop
Causes symptoms of heat
Progesterone – produced by the corpus luteum and the uterus in later stages of pregnancy
Maintains pregnancy
Used to synchronize estrous
Progesterone and estrogen are mutually exclusive

11. Hormones Oxytocin – causes milk letdown and induces labor
Prolactin - lactation
Adrenaline ( epinephrine)
Secreted by the adrenal glands
Causes a “flight or fight” syndrome
Neutralizes oxytocin

12. This cycle of egg development in cattle is called the estrous cycle
. This cycle of egg development in cattle is called the estrous cycle. The cow is a non seasonal polyestrous species. Which means a cow can multiple estrous cycles throughout the year.   Two prominent structures are present within the ovary, the follicle and corpora lutea.
have
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14. Estrous Cycle
The ovarian changes during a typical 21-deay estrous cycle in which pregnancy does not occur.
The development and regression of the corpus luteum and of the follicles are continuous processes

15. The Estrous Cycle Mare Sow Ewe Cow Gyp 18 months 24 months 21 days
Animal
Age at
Puberty
Age of
First Service
Length of
Estrous Cycle
Length of Estrous
Gestation Period in days
Mare 18
months
24 months
21 days
5 days
336
Sow
6 months
8-10 months
18 hours
114
Ewe
6-12 months (first fall)
First fall
Or 2nd
16 days
2 days
150
Cow
6-18 months
14 months
283
Gyp
6-12 months
12 months
6 – 12 months
9 days 63

16. Methods of Heat Detection
Visual Appraisal
Gomer Bulls
Electronic device
Ultrasound machine
Marking harness (sheep and goats)
Teaser Stallion

17. Symptoms of Estrous Standing Heat is the best indicator Restlessness
Discharge from vulva
Swollen vulva
Mares will raise tail, and “winking”

18. Heat symptoms in sows Red, swollen vulva
Ears raised with back pressure
Stand for back pressure

19. Heat Detection Device
Monitors electrical conductivity changes in vaginal mucous

20. Gomer Bulls
Have had penis diverted to the side
May have had vasectomies

21. Teaser Stallions
May be lower quality
Are kept near mares to encourage her to “show” heat symptoms

22. Marking Harness on Rams
Ink or chalk filled pad
Color changed between cycles

23. Solar Powered Networked Heat detectors
Electronic device on female, reads pressure and sends signal to headquarters