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Equine > Reproduction > Flashcards

Reproduction Flashcards

1
Q

When do mares begin puberty?

A

18 months ~ most can become pregnant as 2 year olds

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2
Q

What types of breeders are horses?

A

Seasonal polyestrus (long day breeders)

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3
Q

what does breeding occur? (usually)

A
  • breeding season occurs when daylight increases (between April and July)
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4
Q

What is the estrus cycle and how long is it?

A

the time between ovulations

- 21 days (15-26 days)

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5
Q

What is the duration of the estrus cycle?

A

7 days (2-12 days)

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6
Q

When does ovulation occur?

A

near the end of estrus

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7
Q

What is estrus?

A

when the mare shows sexual receptivity to the stallion

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8
Q

What is estrus controlled by?

A

estrogen

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9
Q

What is the behavior of estrus?

A
  • raising of tail
  • urination
  • posturing
  • clitoral eversion (winking)
  • moves in
  • nickers
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10
Q

What is Diestrus?

A

the period of time when the mare rejects the stallion

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11
Q

How long is diestrus?

A

14-16 days

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12
Q

When does diestrus behavior start?

A

within 12 hours of ovulation

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13
Q

What is diestrus controlled by?

A

progesterone

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14
Q

What is the behavior of diestrus?

A
  • pins ears
  • clamps tail
  • switches tail
  • moves away
  • kicks
  • hollers
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15
Q

What hormone(s) peak right before ovulation?

A

LH, FSH, Estrogen

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16
Q

What is inhibin produced by?

A

the granulosa cells of the dominant follicle

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17
Q

What stimulates FSH?

A

GnRH stimulates FSH release from the anterior pituitary

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18
Q

What does FSH stimulate?

A

follicle development

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19
Q

What does the dominant follicle produce?

A

estradiol and inhibin

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20
Q

What does estradiol act on?

A
  • LH secretion

- estradiol receptor sensitivity on dominant follicle

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21
Q

What does inhibin do?

A

decreases GnRH and FSH production and leads to LH surge and ovulation

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22
Q

What does prostaglandin cause?

A

lysis of corpus luteum and allows ovulation

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23
Q

What does high progesterone mean?

A

suppression of LH

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24
Q

What does high estrogen mean?

A

suppression of FSH

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25
Q

When are the transition periods?

A

spring )vernal) and fall (autumnal)

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26
Q

What happens reproductively during the transition periods?

A

time of low reproductive activity, no clear behavior patterns and delayed ovulation or anovulation

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27
Q

When do mares undergo regular cycles?

A

April/May –> Sept.Oct

28
Q

What is reproduction in mares controlled by?

A

photoperiod through pineal gland and melatonin production

29
Q

What influences ovulaition?

A

age, body condition, disease

30
Q

How does decreased daylight effect ovulation? (process)

A

decreased daylight -> increased melatonin production -> decreased GnRH, FSH, and LH

31
Q

What are some reproductive management strategies? (hormone therapy)

A
  • manipulation of seasonality
  • manipulation of normal cyclicity
  • estrus synchronization
  • modification of sexual behavior (eliminate estrus)
  • Introduction of lactation
  • management of high risk pregnancies
  • Induction of abortion and parturition
32
Q

What are the goals of reproductive management?

A
  • induce and early start to the transitional period using imposed lighting regimes and GnRH administration
  • Shorten the duration of the transitional period using administration and withdrawal of progesterone
  • time estrus and ovulation with semen availability
  • estrus synchronization between embryo donors and recipients
33
Q

What is teasing?

A

exposure of mare to stallion

34
Q

How do you get mares ready for breeding?

A
  • teasing
  • serial examinations to determine which mares are transitional or cycling early in season
  • plan hormonal manipulation
  • determine is a CL is present, uterine/cervical tone, monitor changes
  • determine follicle size, monitor changes
  • quantify uterine edema, monitor changes in patterns
35
Q

When does puberty begin for stallions?

A

18 months (8-30 months)

36
Q

How many spermatozoa are there per ejaculation (approx)?

A

100 million

37
Q

What kind of sperm production do stallions have?

A

seasonal production - peak in july

38
Q

What is sperm production controlled by?

A

GnRH

39
Q

What is common for stallions in regard to reproduction?

A

low fertility (50%) and libido

40
Q

What increases the chances of fertilization?

A

semen harvesting and artificial insemmination

41
Q

What is the breeding soundness examination (BSE)?

A

an exam performed after 2 years on a stallion.

  • physical exam
  • semen collection and evaluation (morphology, concentration, motility)
42
Q

What is the goal to reach in the Breeding Soundness Exam?

A

2 billion progressively motile, morphologically normal sperm in 2 collections 1 hours apart.

43
Q

When are mares bred?

A

when in estrus so that ovulation occurs within 48 hours of breeding

44
Q

What is fertility a function of?

A
  • quality of the mare, timing of the insemination, and dose/quantity of the semen
45
Q

What Happens during live cover?

A

mares are bred every other day with stallion

46
Q

When do you use cooled semen?

A

plan to breed once, usually treat mare with hormones when mare has a follicle of 35mm. breed 24 hours later

47
Q

When do you use frozen semen?

A

either fixed time insemination around 24-44 hours after ovulation induction

48
Q

What is lordosis?

A

mating posture by the female horse

49
Q

What are the conception rates per cycle and per season?

A 
cycle = 60-70%
season= 80-90%
50
Q

In what breed is no reproductive technology used/allowed to be used?

A

thoroughbreds

51
Q

How long does pregnancy last for?

A

320-365 days

perterm = 300-320 days

52
Q

How do you detect pregnancy?

A
  • ultrasound is best
53
Q

How do you predict parturition?

A
  1. Electrolytes in milk change
    - 72 hrs = incr. in Ca and Mg
    - 24 hrs = decr. in Na and incr. in K
  2. Colostrum in udder (waxing up)
54
Q

What happens in stage 1 of parturition?

A
  • coordinated forceful uterine contractions
  • cervical dilation
  • Visibly lasts about 4 hours
55
Q

What behaviors are seen in the first stage of parturition?

A

Sweating, cramping, up and down behavior, dripping or streaming milk

56
Q

What happens during stage 2 of pregnancy?

A
  • rupture of the chorioallantois (water breaking)
  • delivery of fetus
  • lasts 5-30 mins
  • once water breaks the amnion (bluish) should be visible at the vulva
57
Q

How logn should delivery take?

A

30 mins or less

58
Q

How does the foal usual leave the mother?

A

2 legs with hoves facing downwards followed by the muzzle

59
Q

What is an example of an emergency during parturition?

A
  • RED BAG: premature separation of placenta from uterus, requires imediate attention because foal asphyxiates
  • Malpositioning requires attention also
60
Q

What happens during phase 3 of parturition?

A
  • passage of placenta
  • normally takes up to 2 hours
  • greater than 4 hours requires attention and treatment
61
Q

What is normal foal behavior after parturition?

A
  • sternal recumbency (1-2mins)
  • suckle reflex (2-20mins)
  • Stand (60mins)
  • Nurse (2hrs up to 7 times per hour)
  • Urination (within 8-12 hrs)
62
Q

When does weaning take in feral horses?

A

8-9 months (until mother becomes pregnant/gives birth again

63
Q

When does weaning take in domestic conditions?

A

4-6 months or earlier

64
Q

What does weaning result in?

A

increased vocalizations, locomotion, and salivary cortisol

65
Q

How do you reduce weaning stress?

A

introducing adults to foal

Equine (9 decks)

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