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Theriogenology > Bovine Breeding Management > Flashcards

Bovine Breeding Management Flashcards

1
Q

what is the length of gestation in cows

A

280 days

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2
Q

what is the period of involution in cows

A

50 days

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3
Q

what is the natural length of the cycle in cows

A

21 days

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4
Q

how many heat cycles do producers have to get cows pregnant and meet their economic target of 1 calf/cow/13 months

A

3

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5
Q

The duration of estrus and # of events during estrus in heifers is higher/lower than in cows

A

higher

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6
Q

The duration and signs associated with estrus are higher/lower in high vs low producing cows

A

lower

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7
Q

overall, the duration of standing estrus over the entire estrus period in cows is under

A

30 seconds!

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8
Q

on average, estrus in cows lasts

A

12-18 hours

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9
Q

what is Heat Detection Rate (HDR)

A

proportion of cows detected in estrus

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10
Q

what is Insemination Risk

A

cows submitted for AI that are in estrus (proportion of AI eligible cows detected in heat)

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11
Q

what is Conception Risk

A

probability that AI results in pregnancy (proportion of breedings that result in pregnancy)

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12
Q

what is the 21-day pregnancy risk roughly equal to

A

HDRxCR

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13
Q

what is 21-day pregnancy risk

A

proportion of open cows that become pregnant every cycle

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14
Q

how many days after ovulation does the CL become mature/responsive

A

7

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15
Q

how quickly does PGF2α cause luteolysis in a mature CL in cows

A

1 day

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16
Q

PGF half life is (seconds/minutes/hours/days)

A

minutes

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17
Q

GnRH is a chain of amino acids. What does this mean

A

if you ingest it, it is digested

18
Q

What hormone, when given exogenously, causes blood/milk levels LOWER than the endogenous hormone

A

progesterone (P4)

19
Q

what is the BIGGEST challenge for bovine producers in getting cows pregnant

A

DETECTION of HEAT

20
Q

what are factors that can confound heat detection in cows (5)

A

confinement, lameness, flooring, comfort, negative energy balance

21
Q

ovulation occurs in cows how many hours after standing heat

A

27h later

22
Q

after ovulation, the ovum lifespan in cows is

A

6-8h

23
Q

capacitation of sperm occurs how many hours after ejaculation

A

10

24
Q

what is the basis of activity monitors for heat detection

A

there is a huge spike in activity the day a cow comes into heat

25
Q

what are the limitations to PGF2α for estrus synchronization in cows (3)

A

1) not all will respond (66% apparent response)
2) need to be able to detect a mature CL
3) variable time to ovulation depending on the phase of the wave in individual cows

26
Q

T/F PGF2α allows for timed AI

A

F (it does not control follicles so it cannot)

27
Q

the average interval from PGF2α to estrus detection is

A

3 days

28
Q

describe OvSynch

A

1) give GnRH on day 1 to stim follicular growth
2) give shot of PGF2α to lyse any CL on day 7
3) give GnRH again 2- 2.5 days later
4) timed AI within the next day

29
Q

T/F OvSynch allows for timed AI

A

T

30
Q

what is a key step to improve fertility during OvSynch

A

ovulating after the first shot of GnRH so that there is a CL producing progesterone during the follicular growth before the dose of PGF2α

31
Q

we want to inseminate ~ how many hours after giving the second dose of GnRH in an OvSynch program

A

16

32
Q

what is the effect on OvSynch if we start 1-4 days after the last heat

A

failure to synchronize new follicular wave

33
Q

what is the effect on OvSynch if we start 13-17 days after the last heat

A

spontaneous luteolysis and ovulation before timed AI

34
Q

what is the effect on OvSynch if we start 18-21 days after the last heat

A

unresponsive CL when we give PGF

35
Q

how many days after the last ovulation is ideal to start OvSynch

A

5-12 (but goal of presynching is to get them at 6-7 days)

36
Q

what are the two methods of pre-synchronizing the estrus cycle before starting OvSynch

A

1) Pre-Synch: 2 PGF, 2 weeks apart, 2 weeks before OVS
2) Double OvSynch: Ovsynch -> no AI -> 7d -> OvSynch -> timed AI

37
Q

what is the goal of pre-synchronization

A

start OvSynch when the cows are 6-7 days after the last ovulation

38
Q

what can be used to stimulate ovulation in anestrus cows

A

CIDRs (intravaginal progesterone)

39
Q

what 2 uses can CIDRs be used for

A

1) bring cow out of anestrus
2) stimulate turnover in cystic cows

40
Q

what is a potential side-effect of using CIDRs in cows

A

if used for longer than 14 days, it produces a persistent dominant follicle (cyst) -> reduced fertility

Theriogenology (18 decks)

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