The Effect of Hormones on The Effect of Hormones on the Estrous Cyclethe Estrous Cycle

Hypothalmus- Hypothalmus- primitive part of the brain primitive part of the brain that controls other endocrine glands. that controls other endocrine glands. Stimulates the pituitaryStimulates the pituitary

Pituitary GlandPituitary Gland –at the base of the brain. –at the base of the brain. Regulates hormone secretion throughout the Regulates hormone secretion throughout the body.body.

FSHFSH – Follicle Stimulating Hormone. Causes – Follicle Stimulating Hormone. Causes the follicle to mature.the follicle to mature.

Lutenizing HormoneLutenizing Hormone – causes ovulation – causes ovulation and the formation of the corpus luteum.and the formation of the corpus luteum.

Hormones Hormones Estrogen-Estrogen- Prepares the cow for sexual activity. Prepares the cow for sexual activity.

“Heat”“Heat”

ProgesteroneProgesterone, , secreted by the corpora lutea, secreted by the corpora lutea, Stops the development of follicles Stops the development of follicles Stops estrogen. Stops estrogen. Stops cow from coming into heat. Stops cow from coming into heat. prepares the uterus to receive the prepares the uterus to receive the

fertilized egg maintains pregnancy.fertilized egg maintains pregnancy.

Follicle stimulating hormoneFollicle stimulating hormone (FSH) (FSH) and and luteninizing hormoneluteninizing hormone (LH) are (LH) are secreted & travel through the blood to secreted & travel through the blood to the ovary. the ovary.

FSH and LH are mediated by FSH and LH are mediated by gonadotropic releasing hormonegonadotropic releasing hormone (GnRH) coming from the hypothalamus (GnRH) coming from the hypothalamus to signal their release from the to signal their release from the pituitary. pituitary.

FSH stimulates the growth, FSH stimulates the growth, development and function of the development and function of the follicle, while LH cause the follicle to follicle, while LH cause the follicle to rupture during ovulation and causes rupture during ovulation and causes the subsequent development of the the subsequent development of the corpus luteum.corpus luteum.

http://www.mothercow.org/bull/barnyard/hormones.jpg

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.

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

Follicle produced by FSHFollicle produced by FSH

This follicle will soon This follicle will soon rupture(ovulation) with the rupture(ovulation) with the

help of LHhelp of LH

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

progesterone.progesterone.

EstrousEstrous

Heat is the time when a female is Heat is the time when a female is receptive to the male and will allow receptive to the male and will allow breeding to take placebreeding to take place

Heat is actually divided into 4 phases Heat is actually divided into 4 phases of the cycle.of the cycle.

Phases of EstrousPhases of Estrous

ProestrusProestrus: ovary is about to release an : ovary is about to release an eggegg

EstrusEstrus: female receptivity: female receptivity MetestrusMetestrus: uterus prepares for pregnancy: uterus prepares for pregnancy

fertilized egg attaches to uterusfertilized egg attaches to uterus DiestrusDiestrus: longest period of cycle: longest period of cycle

inactiveinactive Estrous Cycles stop after conception, and Estrous Cycles stop after conception, and

begin soon after Parturition (birth)begin soon after Parturition (birth)

HormonesHormones

Estrogen – produced by the ovaryEstrogen – produced by the ovary causes secondary sexual characteristics to developcauses secondary sexual characteristics to develop Causes symptoms of heatCauses symptoms of heat

Progesterone –Progesterone – produced by the corpus luteum and produced by the corpus luteum and the uterus in later stages of pregnancythe uterus in later stages of pregnancy

Maintains pregnancyMaintains pregnancy

Used to synchronize estrousUsed to synchronize estrous

Progesterone and estrogen are mutually exclusiveProgesterone and estrogen are mutually exclusive

HormonesHormones

Oxytocin – causes milk letdown and Oxytocin – causes milk letdown and induces laborinduces labor

Prolactin - lactation Prolactin - lactation

Adrenaline ( epinephrine)Adrenaline ( epinephrine) Secreted by the adrenal glandsSecreted by the adrenal glands Causes a “flight or fight” syndromeCauses a “flight or fight” syndrome Neutralizes oxytocin Neutralizes oxytocin

have

have

. 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.

Estrous CycleEstrous Cycle

The ovarian The ovarian changes during a changes during a typical 21-deay typical 21-deay estrous cycle in estrous cycle in which pregnancy which pregnancy does not occur. does not occur.

The development The development and regression of and regression of the corpus luteum the corpus luteum and of the follicles and of the follicles are continuous are continuous processesprocesses

http://www.cahe.nmsu.edu/pubs/_b/b-212.pdf

The Estrous CycleThe Estrous Cycle

AnimalAnimal Age atAge at

PubertyPubertyAge ofAge of

First ServiceFirst ServiceLength ofLength of

Estrous CycleEstrous CycleLength of Length of EstrousEstrous

Gestation Period Gestation Period in daysin days

MareMare 18 18

monthsmonths24 24 monthsmonths

21 days21 days 5 days5 days 336336

SowSow 6 6 monthsmonths

8-10 8-10 monthsmonths

21 days21 days 18 18 hourshours

114114

EweEwe 6-12 6-12 months months (first (first fall)fall)

First fallFirst fall

Or 2ndOr 2nd16 days16 days 2 days2 days 150150

CowCow 6-18 6-18 monthsmonths

14 14 monthsmonths

21 days21 days 2 days2 days 283283

GypGyp 6-12 6-12 monthsmonths

12 12 monthsmonths

6 – 12 6 – 12 monthsmonths

9 days9 days 6363

Methods of Heat DetectionMethods of Heat Detection

Visual AppraisalVisual Appraisal

Gomer BullsGomer Bulls Electronic deviceElectronic device Ultrasound machineUltrasound machine Marking harness (sheep and goats)Marking harness (sheep and goats) Teaser StallionTeaser Stallion

Symptoms of EstrousSymptoms of Estrous

Standing Heat is Standing Heat is the best indicator the best indicator

RestlessnessRestlessness Discharge from Discharge from

vulvavulva Swollen vulvaSwollen vulva Mares will raise Mares will raise

tail, and “winking”tail, and “winking”

Heat symptoms in sowsHeat symptoms in sows

Red, swollen vulvaRed, swollen vulva

Ears raised with Ears raised with back pressureback pressure

Stand for back Stand for back pressurepressure

Heat Detection DeviceHeat Detection Device

Monitors electrical Monitors electrical conductivity conductivity changes in vaginal changes in vaginal mucousmucous

Gomer Gomer BullsBulls

Have had Have had penis penis diverted to diverted to the sidethe side

May have May have had had vasectomiesvasectomies

Teaser StallionsTeaser Stallions

May be lower qualityMay be lower quality Are kept near mares to encourage Are kept near mares to encourage

her to “show” heat symptomsher to “show” heat symptoms

Marking Harness on RamsMarking Harness on Rams

Ink or chalk filled Ink or chalk filled padpad

Color changed Color changed between cyclesbetween cycles

Solar Powered Networked Heat detectors

Electronic device on female, reads pressure and sends signal to headquarters