Reproductive Manipulation of the Mare

Question 1

What is the mare’s repro cycle called?

Answer 1

Seasonally polyestrous

Question 2

Are mares short or long day breeders?

Answer 2

Long day

Question 3

When do mares reach puberty?

Answer 3

About 15 months

Question 4

What are the 2 periods of the mare’s cycle and what is happening during them?

Answer 4

Anestrus -> no repro activity
Estrous -> cyclicity

Question 5

Mares have a ____ day gestation with ____ days being the length of estrus

Answer 5

340 day gestation; 5-7 day estrus length

Question 6

Mares have ___ transition periods in their cycle? When are they?

Answer 6

2; one before estrous and one before anestrous

Question 7

When is the mare’s estrous period typically?

Answer 7

Mid April- mid September

Question 8

What is the average length of estrous?

Answer 8

19-22 days (21 days= average)

Question 9

What are the two stages in the estrous cycle and how long are they?

Answer 9

Diestrus (14-15 days)
Estrus (5-7 days)

Question 10

What primary hormone is in estrus? Diestrus?

Answer 10

Estrus- estrogen from ovary
Diestrus - progesterone from CL

Question 11

What does prostaglandin do?

Answer 11

Produced when there is no pregnancy and goes into anestrus (typically during winter)

Question 12

Increased sunlight causes a decrease in what hormone? Which in turn causes an increase in what other hormones?

Answer 12

Decrease in melatonin from pineal gland, increased GnRH from hypothalamus which causes increase in LH and FSH from the pituitary gland

Question 13

Ovulation occurs towards the end of ___?

Answer 13

Estrus

Question 14

Mares cease estrus behavior ________ hours following ovulation?

Answer 14

24-48 hours

Question 15

Compared to other livestock species, the horse has the most _______ in their repro cycle? what does this mean for horses?

Answer 15

Variation; means their pregnancy rates tend to be lower

Question 16

You should breed your mare if you see 2/3 signs, what are these signs?

Answer 16

Showing heat, cervix is open, a 35 mm follicle is present

Question 17

Why should we use photo stimulation on mares?

Answer 17

Create a longer day to breed sooner in the year, hastens onset of ovulatary season

Question 18

When should we begin using photostimulation?

Answer 18

Before winter solstice (12/21)

Question 19

When to start artificial lights and why?

Answer 19

Start Nov 1-Dec1 bc it takes about 60 days to get them to cycle

Question 20

Traditional methods for lights is ___ days of light and ___ days of dark?

Answer 20

16 light and 8 dark

Question 21

When is artificial light the most effective during the day?

Answer 21

End of day’s natural light, must be consistent

Question 22

Specific time for night-interruption?

Answer 22

9.5 hours after onset of darkness

Question 23

Name an agonist used in horses?

Answer 23

Deslorelin, busrelin, histrionic

Question 24

Name a drug used as an agonist and what it does?

Answer 24

SucroMate, LH like activity makes mares ovulate within 48 hours for multiple cycles a year

Question 25

HCG is a large what? used to?

Answer 25

Glycoprotein used to induce ovulation

Question 26

What is one product often used in mares for hCG?

Answer 26

Chorulon

Question 27

HCG is most effective in what horses?

Answer 27

Young mares that havent gotten this previously or the first 2-3 times in the breeding season for middle aged mares

Question 28

What is the goal of using FSH in the mare?

Answer 28

Superovulation

Question 29

What types of FSH have worked in the mare?

Answer 29

EFSH (purified equine FSH) and reFSH (recombinant equine FSH)

Question 30

When to give a mare FSH to induce superovulation?

Answer 30

2x 5-7 days post ovulation with a 20 mm follicle, stop at 32-35 mm follicle

Question 31

What does PGF 2 alpha do in the mare?

Answer 31

Short cycling, estrous synchronization, persistent CL, and termination of pregnancy

Question 32

Does PGF 2 alpha work on anetrus mares?

Answer 32

No

Question 33

Uses of progesterone, progestins, and estrogens in the mare

Answer 33

Suppress behavioral estrus, synchronize estrus, maintain pregnancy

Question 34

How is progesterone and estrogen given to the mare?

Answer 34

IM or orally