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AI and Palpation > Estrous Synchronizatio and Pregnancy > Flashcards

Estrous Synchronizatio and Pregnancy Flashcards

1
Q

how long is the bovine estrous cycle

A

21 days

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2
Q

how long is a cow in estrus?

A

12 hours

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3
Q

if you have 100 cows with normal estrous cycles, how many will be in estrus each day?

A

5 cows per day

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4
Q

what are the potential advantages of estrus synchronization?

A 
increasing estrus detection timing and accuracy
AI timing (timed AI, on drug protocols)
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5
Q

what are the advantages of estrus synchronization on a dairy production?

A

control lactation cycle, control days open

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6
Q

what does days open mean?

A

the time after the baby is born before rebreeding

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7
Q

what are the advantages of estrus synchronization in a beef production?

A

reduce breding season, control calving season and production cycles

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8
Q

list and give the function of the hormones of the estrous cycle

A
  1. LH: causes ovulation
  2. FSH: follicle growth
  3. Estradiol: estrus
  4. PGF2a: corpus luteum regression
  5. GnRH: gonadotropin releasing hormone, controls FSH and LH
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9
Q

list the 3 main ovarian events, plus what happens if no embryonic signal detected

A
  1. waves of follicles developing- dominant follicle ovulates
  2. P4: inhibits estrus and ovulation
  3. Day 10-12 embronic signal, if present
    if not pregnant: PGF2a causes regression of CL, dropping P4, P4 inhibtion is removed, the final follicle matures, causing estrus and ovulation
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10
Q

why are there waves of follicular growth?

A

there need to be additional follicles ready if there is no baby, this growth and regression leads to follicular waves even during pregnancy

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11
Q

at what point in the estrous cycle would a function CL be present?

A

5-15 days

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12
Q

what if we gave exogenous PGF2a when a functional CL is present (day 5-15)?

A

CL should regress, and estrus will occur in 48-96 hours

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13
Q

what is the level of response following a single PGF2a injection? break down the percentage

A

75% in estrus
50% from shot (5-15) days + 25% natural estrus (were in days 15-21 of cycle)
no effect from cows in days 0-5 of cycle, since no CL

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14
Q

what if you use estrus detection and breed for 5 days, then PGF2a shot?

A

in theory should have 100% in estrus, 25% from observation and 75% from single shot

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15
Q

what if you give PGF2a (0d) plus a 2nd shot of PGF2a at (12d)?

A

100% in theory, estrus in 48-96 hours

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16
Q

what will PGF2a do if an animal is pregnant?

A

will cause abortion

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17
Q

why do you need to wear gloves when handling PGF2a?

A

it is highly fat-soluble so it can be absorbed through the skin

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18
Q

what happens if PGF2a is absorbed through the skin?

A

will alter normal menstrual cycles, can also cause smooth muscle contractions in individuals who are sensitive to it = fucks up GI tract

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19
Q

what does P4 do?

A

preparation maintenance of tract for gestation, inhibits estrus and ovulation

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20
Q

what if we provide exogenous P4 source for 10-14 days to cows with normal estrous cycles? and then remove the source?

A

post-removal = 100% estrus in 48-96 hours (catch them at all points of cycle)

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21
Q

what are some exogenous sources of progesterone?

A

CIDRs, implants, feed additives

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22
Q

what is the easiest exogenous source P4?

A

CIDR (controlled internal drug release)

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23
Q

what does GnRH do?

A

causes release of FSH and LH

24
Q

when GnRh releases FSH and LH, what follows?

A

the luteal phase, which is “follicle wars” where follicles compete to be the new lead follicle

25
Q

when GnRH releases just LH, what follows?

A

the follicular phase, or ovulation

26
Q

if you were to give GnRH, wait 7 days, give PGF2a, wait 36-48 hours, and then give more GnRH, what would happen?

A

first dose of GnRH would eliminate current follicular wave, PGF2a will cause luteolysis, second GnRH will cause the dominant follicle to ovulate, and then you can do timed AI in 8-18 hours

27
Q

list 4 different advantages of pregnancy determination in dairy cows

A
  1. milk production
  2. DAYS OPEN
  3. detecting abnormalities
  4. estrus/breeding efficiency
28
Q

elaborate on why dyas open is such an advantage of pregnancy determination in dairy cows

A

great estimate on reproductve efficiency, the goal is to have a cow open for 100-110 days, and you lose $2-$5 per cow per day for each day beyond 90 days open

29
Q

list 6 advantages of pregnancy determination in beef cows?

A
  1. limited breeding season
  2. pregnancy determination- selection/maintenance
  3. estimate calving dates
  4. detecting abnormalities
  5. estrus/nreeding efficiency
  6. sire effeciency
30
Q

if a cow is not pregnant at the end of breeding season, how long until she can potentially produce another calf (her product)

A

2 years

31
Q

list 3 methods of pregnancy determination

A
  1. palpation
  2. ultrasound
  3. blood test (PAG)
32
Q

when can pregnancy be detected with palpation? can you detect the age or sex of the calf? do you need an experienced technician?

A

35-50 days, can detect age but not sex, needs an experienced technician

33
Q

what is the approximate cost per cow of palpation as pregnancy determination, and when do you know results?

A

$3-$10 per cow, know results immediately

34
Q

when can pregnancy be deteched with ultrasound? can you detect the age or sex? do you need an experienced technician?

A

30 days, can detect age and potentially sex, need an experienced technician

35
Q

what is the approximate cost per cow of ultrasound as a method of pregnancy determination and when do you know results?

A

$7-$15, know results immediately

36
Q

when can you detect pregnancy with a blood test, do you kmow the age or sex of the calf? do you need an experienced technician?

A

28-30 days, can not detect age or sex, do not need an experienced technician

37
Q

what is the approximate cost per cow of a blood test (PAG) and wen do you know results?

A

$3-$5 , get results in 1-4 days

38
Q

what does the PAG mean in a blood test?

A

pregnancy associated glycoprotein- protein B

39
Q

where does PAG come from, and when is it measurable until?

A

calf-induced product- early pregnancy recognition factor (EPRF)measurable around 30 dyas post-fertilization

40
Q

what are the challenges of using a PAG blood test to determine pregnancy? (3)

A
  1. 5-8% false positive or negative results
  2. present up to 60 days post-calving (from previous pregnancy)
  3. may remain detectable up to 60 days post-abortion
41
Q

why is ultrasound a difficult method to detect pregnancy?

A

cows are big, you need lots of radiation, it’s hard to navigate the instrument in the tract, and you’re already palpating anyway so you might as well just palpate instead

42
Q

what is the downside of palpation as a method of determining pregnancy?

A

it will be longer before you can detect pregnancy with just palpation

43
Q

what is a palpation method that can be done prior to 50 days as a method to determine pregnancy?

A

fetal membrane slip

44
Q

what is felt for in a fetal membrane slip?

A

the placenta; will feel the chorioallentois sliding between your fingers and the uterine wall

45
Q

when do placentomes completely attach?

A

40-50 days

46
Q

what are placentomes made of?

A

cotyledons and caruncles

47
Q

what are 2 challenges of fetal membrane slip as a pregnancy detection method?

A
  1. it is hard

2. potential damage to fetus/placental attachment

48
Q

what is a definitive method of palpation as a determination of pregnancy?

A

placentome palpation

49
Q

what part of the placentome does the cow contribute?

A

the caruncle

50
Q

what part of the placentome does the calf contribute?

A

the cotyledon

51
Q

how many placentomes are there in cattle?

A

60-120

52
Q

what is the least risky form of palpation as a method of pregnancy determination and when is it performed?

A

fetal palpation, 3 months or later into pregnancy

53
Q

where will the fetus be located past 60 days into pregnancy? and why?

A

right side of pelvic rim; rumen is on the left

54
Q

what is the natural advantage of using your left hand to palpate?

A

it will naturally reach to the right towards the repro tract, away from the rumen on the left

55
Q

where do you go with your hand in AI and why?

A

go shallow, cervix is usually in the pelvic rim

56
Q

where do you go with your hand in a pregnancy test and why?

A

go deep and retract, cow grows from bottom up

AI and Palpation (4 decks)

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