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541 (sex class) > dairy 1 > Flashcards

dairy 1 Flashcards

1
Q

what is the target for dairy cattle reproduction?

A

1 calf per year

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2
Q

tell me the length of:
1. gestation
2. how many days cow isn’t pregnant
3. how many days she’s in lactation
4. how many days she’s dry

and then tell me when these are relative to each other

A
  1. 283 days pregnant (~280)
  2. 82 days ish
  3. 305 days
  4. 60 days
  • cow is dry during the 60 days leading to calving
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3
Q

what are the 3 groups of cows you’re looking at during health visits?

A
  1. fresh/transition cows
  2. preg checks
  3. repeater cows
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4
Q

when you’re doing a health check and looking at fresh/transition cows, what are you looking for?

A

palpate that uterus is correct size. should be similar to original size by 3 weeks postpartum

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5
Q

tell me the timeline from a transition cow to back to lactating

A

transition cow not producing milk (dry cow) –> calving –> producing milk (-3wk to +3wk from calving)

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6
Q

why which day post partum should the dairy cow uterus have no fluid and be retractable?

A

> 21 days

earlier it’s still involuting

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7
Q

if you find abnormal involution in a fresh dairy cow, what are 3 things you can look at for causes?

A

nutrition, mangement, environment

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8
Q

when do you do preg checks on dairy cattle?

A

> 35 days

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9
Q

what are repeater cows?

A

3+ unsuccessful AI’s (>90 days open)

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10
Q

what 5 things make up the ideal transition cow?

A
  • calving w/o complications
  • free of metabolic or infectious disease
  • recovers feed intake
  • rapid increase in milk production
  • return to reproductive cyclicality (important)
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11
Q

what is the voluntary waiting period? why does this occur?

A

period of time after parturition where you voluntarily don’t breed cow even though she is in estrus.

1st ovulation silent w/ short life CL
2nd ovulation (25-30d) low quality oocyte = low fertility

don’t waste time and resources!

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12
Q

tell me what the hormones are doing to make a cow ovulate

why is there no FSH surge?

A
  1. release of PGF2alpha
  2. decrease P4 –> destroyed CL
  3. increase E2 + inhibin
  4. GnRH surge
  5. LH surge
  6. ovulation

no FSH surge bc E2 + inhibin = inhibits FSH release

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13
Q

tell me the 3 follicular development stages of the antral follicles (tertiary)

A
  1. recruitment/emergence
  2. selection/deviation
  3. dominance
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14
Q

follicular development: recruitment/emergence stage
1. length?
2. what’s happening
3. hormone dependent?

A
  1. 2-3 days
  2. 8-41 follicles of 1-4mm to reach 9-10mm
  3. FSH dependent
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15
Q

follicular development: selection/deviation stage
1. length?
2. what’s happening
3. hormone dependent?

A
  1. 2 days
  2. selected follicle continues to grow to a dominant follicle
  3. LH/FSH transfer dependency (follicles change dependency from FSH to LH)
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16
Q

follicular development: dominance stage
1. length?
2. what’s happening
3. hormone dependent?

A
  1. no length per se, but the follicle is >16mm
  2. dominant follicle continues to grow
  3. LH dependent, E2 increases which is the preovulatory signal
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17
Q

how do you differentiate between dominant and non-dominant (atretic) follicles on US?

A

the dominant one will be bigger (~14-16mm) and the atretic ones will be smaller

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18
Q

tell me how P4, LH, FSH and E2 all work together to promote/deny follicular development

A
  • FSH recruits a group of follicles to grow
  • LH pulses stimulate dominant follicular growth
  • high P4 suppresses LH pulses and maintains dominant follicle at 16-20mm
  • if P4 is high, follicle will undergo atresia because LH is low
  • low E2 = high FSH = recruitment of follicule to grow
  • if low P4, ovulation proceeds
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19
Q

95% of cycles have ____ follicular waves. Heifers with high P4 have ____ waves.

A

2-3 waves
heifers have 3

20
Q

the 1st wave oocyte is ____ fertility

A

low

21
Q

tell me the difference in days between a 2-wave cycle and 3-wave cycle

A

2-wave:
- 1st wave: d0
- 2nd wave: d9-10
- luteolysis: d16

3-wave:
- 1st wave: d0
- 2nd wave: d8-9
- luteolysis: d19

22
Q

a 2 wave cycle is ___ than a 3 wave cycle

A

shorter

23
Q

What is an ovarian cyst, or Cystic Ovarian Disease (COD)?

A

anovulatory follicle that persists from 6-10 days, >20mm in diameter, with no active luteal tissue (CL)

24
Q

what is the incidence of ovarian cysts in dairy cattle?

A

6-30% b/t days 16-50

25
Q

how do you tx COD?

A

sx - depending on level of luteinization (P4 production)

26
Q

how do you dx COD?

A
  • anestrus during post-partum
  • irregular estrus intervals; nymphomania; masculine aggressive and sexual behaviour
27
Q

what are the risk factors for COD?

A
  • increase milk yield
  • NEB
  • stress
  • age
  • nutritional status
28
Q

that is the pathogenesis of COD?

A

high-yield cows - NEB
1. sub-luteal P4 AND/OR inadequate E2
2. lower LH receptors
3. growing follicle = decreased sensitivity to LH
4. no ovulation
5. persistent dominant follicle, arrest of follicular waves
6. anovulation and anestrus

29
Q

what is the difference between an ovarian cyst in the follicular phase vs the luteal phase?

A

follicular: thin wall < 3mm, not luteinizing, still producing high conc E2
luteal: thick wall >3mm, luteinizing, producing P4

30
Q

how would you tx a follicular ovarian cyst vs a luteal ovarian cyst?

A

follicular: gonadorelin (GnRH agonist) –> pushes cyst to luteinize
luteal: prostaglandin –> destroys CL

31
Q

what is the goal of synchronization?

A

increase fertility (conception rate) by decreasing the time the cow is not pregnant after calving (open days)

get animal pregnant as soon as voluntary waiting period is done

you basically move an animal from being a spontaneous ovulator to an induced ovulator bc you induce w drugs

32
Q

what are the 2 types of synchronization?

A
  1. estrus synchronization
  2. ovulation synchronization
33
Q

describe estrus synchronization principles

A

look for estrus behaviour - once you see it, AI

if animal in estrus in AM, inseminate in afternoon (PM)

if animal in estrus in PM, inseminate next morning (AM)

AM-PM, PM-AM rule (ideal time to AI is 4-16 hours after onset of standing estrus)

34
Q

describe ovulation synchronization principles

A

control follicular growth and induce ovulation

not assoc. w/ estrus, inseminate at fixed time (FTAI)

35
Q

sperm must spend _____ in female repro tract to be mature enough to fertilize.

A

6-8h

36
Q

name 4 drugs used in synchronization and what they do

A
  1. prostaglandins (PGF2alpha) [dinoprost] = destroys CL
  2. GnRH [gonadorelin] = release FSH and LH
  3. progesterone [CIDR/PRID] = enhances CL growth, but more importantly, needed for oocyte quality
  4. E2 (banned in NA, EU, Oceania) = increase GnRH
37
Q

tell me how you would use estrus synchronization

A
  • start with PGF2alpha (destroy CL, get rid of P4, allow follicle growing to become dominant and preovulatory)
  • prerequisite = responsive CL (>6d & <18d)
  • estrus detection is important
  • inject with PG 11-14 days apart (CL will be susceptible to PGF2alpha at least one of these times)
38
Q

how can you detect estrus behaviour?

A

primary estrus sign = standing to be mounted (but 50% don’t do this)

secondary signs include: mounting/following other cows, restlessness (increased activity), red vulva, swollen and crystalline mucus discharge, reduce feed intake/rumination and milk prod

39
Q

what are the factors that can influence outward estrus behaviour?

A
  • environment (housing, flooring, temperature)
  • nutrition
  • cow density and other cows in estrus
  • hoof and leg health
40
Q

why is estrus synchronization not used typically?

A

because watching for estrus behaviour is hard and labor intensive

41
Q

in cattle, ova viability is ___ and sperm viability is ____.

A

ova: 12-36h
sperm: 30-48 h

42
Q

tell me how you would use ovarian synchronization

A
  • facilitates AI at a fixed time (FTAI) = no estrus detected needed
  • a dominant follicle is necessary to respond ot GnRH
  • most common and successful system = OvSynch
43
Q

tell me the steps of OvSynch, including what each medication does.

A

OvSynch:
- inject GnRH Day 0 (induce LH surge, synchs pre-ovulatory follicle wave, increase P4 contractions)
- PG 7 days later (lyse CL, must wait until it’s responsive to PG, synch decrease in P4, initiate proestrus)
- GnRH 2 days after (again LH surge for ovulation, synch timing of ovulation and AI)
- insem 1 day later

44
Q

when is the ideal time to start OvSynch protocol? why?

A

day 6-7

when GnRH is given on day 6 of estrous cycle, there is already a CL. when GnRH is given, the animal is recruiting 1st follicular waves and follicle is large enough to be responsible to GnRH. the follicle will ovulate and form a CL, so there’s the CL you made plus the original one. then 7 days later inject PG and both are responsive to PG

45
Q

how do make sure that we are on day 6-7 before starting OvSynch?

A

resynchronization so all cows submitted to OvSynch are in day 6-7 of estrous cycle

Double OvSynch:
- 1st ovsynch ensures that 2nd ovsynch will start on day 6-7
- this protocol would be begun during the voluntary waiting period

541 (sex class) (22 decks)

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