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Breeding > Factors Affecting Reproductive Performance (Other factors) > Flashcards

Factors Affecting Reproductive Performance (Other factors) Flashcards

1
Q

Recording

A

Most reproductive events are dates

Records helps in :
1. Monitoring and evaluating reproductive performance
2. Anticipation of next events (e.g. heat , dry off dates and calving dates)

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2
Q

Paper records (e.g. heat expectancy charts) and printouts of computerized records are used to list cows that are …

A

expected to enter estrus each day (DairyComp 365)

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3
Q

Heat Stress

A

The thermoneutral zone for dairy cows is 5-25 C

THI > 68 heat stress begins

Heat stress negatively affects :
1. Follicular growth
2. Ovulation
3. Expression of estrus
4. The establishment of pregnancy

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4
Q

The thermoneutral zone for dairy cows is …

A

5-25 C

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5
Q

Temperature humidity index (THI) > …. heat stress begins

A

68

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6
Q

Heat Stress Other effects

A
  1. Decreased Feed intake
  2. Negative energy balance
  3. Decreased GnRH – Low FSH & LH
  4. Decreased estradiol secretion
  5. Low P4 from CL
  6. High uterine temperature
  7. Poor estrus expression
  8. Prolonged follicular dominance
  9. Low fertilization rate
  10. Poor embryo quality
  11. Compromised uterine environment
  12. Embryonic loss
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7
Q

Mitigation of heat stress

A
  • Cooling cows by providing fresh cool drinking water, shade, water sprays; fans, and tunnel ventilation
  • Use Curtains
  • Controlled breeding (hormone treatments)
  • Using heat-tolerant breeds and genetic selection for heat tolerance
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8
Q

Timing of Insemination or Service

A
  1. Voluntary Waiting Period (VWP)
  2. Timing relative to ovulation
    A. Artificial insemination
    B. Using a bull
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9
Q

Voluntary Waiting Period (VWP)

A

50 d (after normal calving), 60 d (after a problem calving e.g RFM or uterine infection)

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10
Q

The aims of VWP are

A
  • To provide enough time for the reproductive tract to recover from the effects of pregnancy (uterine involution usually takes 6 weeks)
  • The cow is not in excessive NEB (most severe the firsts weeks of lactation)
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11
Q

Estrus

A

15 hours

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12
Q

Sperm viability

A

18 - 24 h (maybe 48 h)

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13
Q

Sperm transport

A

6 h

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14
Q

Optimal time to inseminate

A

End of estrus

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15
Q

Ova viability

A

8 - 10 h (maybe 20 h)

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16
Q

Ovulation

A

24 – 32 h from onset

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17
Q

Cows should be inseminated during the ….

A

last half of estrus (towards end of estrus)

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18
Q

Am-pm rule (morning-evening )

A

Cows first detected in estrus in the morning are inseminated the same evening and cows first detected in estrus in the evening are inseminated the next morning

19
Q

Single mid-morning

A

If it is difficult to determine the onset of heat

Inseminate cows that have been observed in estrus the same morning or the night before would give optimal conception rates

20
Q

Timing relative to ovulation (Using a bull)

A
  • The pheromones by the cow and her behavior tell the bull the right time to serve her
  • The success is due to several matings through the heat
21
Q

Early lactation is usually characterized by …

A

NEB

22
Q

Animals have a clear priority for energy when there is NEB, such that …

A

maintenance and lactation take priority overgrowth and reproduction

23
Q

NEB effect in fertility

A

fertility is impaired

24
Q

Body Condition Score (BCS)

A

Energy reserves of dairy cows

25
Q

Recommended BCS at calving = …

A

3.5

26
Q

Recommended loss < 1 BCS from calving to …

A

60 DIM

27
Q

> 1 BCS loss during the first 5 weeks of lactation

A

impaired fertility

28
Q

BCS range

A

1 (very thin) to 5 (extremely fat)

29
Q

The most frequent cause of nutritional infertility

A

Energy deficiency (underfeeding or loss of BW during early lactation)

30
Q

Protein

A
  • High yielding dairy cows require 18% to 19% CP
  • Low levels (< 16% CP) affect reproductive activity.
  • High levels of dietary protein intake (> 19% CP) can impair fertility
31
Q

Micronutrients

A
  • Phosphorus is the most prevalent mineral deficiency affecting reproduction
  • The calcium/phosphorus imbalance has a similar effect
32
Q

Embryonic Loss

A
  • About 30% of all pregnancies in cattle will not survive to birth
  • Most cases (>90%) are EED (within 42 d of insemination)
  • Affected cows will return to estrus “repeat breeders”
  • The causes are not known. May include lactational stress , NEB, high urea and ammonia, heat stress and infection
33
Q

About … of all pregnancies in cattle will not survive to birth

A

30%

34
Q

Most cases (>90%) are …

A

EED (within 42 d of insemination)

35
Q

How Can I short Cl ?

A

Early pregnancy diagnosis and early rebreeding

36
Q

Early detection of the nonpregnant cows is important for …

A

early rebreeding

37
Q

Pregnancy Diagnosis

A

Progesterone assay
Ultrasound (transrectal)

38
Q

Progesterone assay

A
  • In milk 21- 24 d after insemination
  • Automated systems (Herd Navigator TM) measures milk P4 at each milking
  • On-farm rapid (within 1 h) qualitative P4 assay kits is available
39
Q

Ultrasound (transrectal)

A
  • It is the method of choice for the early diagnosis of pregnancy in the cow
  • Accurate (99%)
40
Q

1st Ultrasound (transrectal) exam

A

26 - 28 d
To detect non-pregnant cows

41
Q

2nd Ultrasound (transrectal) exam

A

56 d
Because of high EEL

42
Q

Insemination is not recommended before ….. after calving

A

6 - 7 weeks

43
Q

If uterus temp. increased .5% → Conception rate will decrease

A

7%

Breeding (15 decks)

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