Factors Affecting Reproductive Performance (Other factors)

Question 1

Recording

Answer 1

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)

Question 2

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

Answer 2

expected to enter estrus each day (DairyComp 365)

Question 3

Heat Stress

Answer 3

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

Question 4

The thermoneutral zone for dairy cows is …

Answer 4

5-25 C

Question 5

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

Answer 5

68

Question 6

Heat Stress Other effects

Answer 6

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

Question 7

Mitigation of heat stress

Answer 7

• 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

Question 8

Timing of Insemination or Service

Answer 8

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

Question 9

Voluntary Waiting Period (VWP)

Answer 9

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

Question 10

The aims of VWP are

Answer 10

• 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)

Question 11

Estrus

Answer 11

15 hours

Question 12

Sperm viability

Answer 12

18 - 24 h (maybe 48 h)

Question 13

Sperm transport

Answer 13

6 h

Question 14

Optimal time to inseminate

Answer 14

End of estrus

Question 15

Ova viability

Answer 15

8 - 10 h (maybe 20 h)

Question 16

Ovulation

Answer 16

24 – 32 h from onset

Question 17

Cows should be inseminated during the ….

Answer 17

last half of estrus (towards end of estrus)

Question 18

Am-pm rule (morning-evening )

Answer 18

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

Question 19

Single mid-morning

Answer 19

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

Question 20

Timing relative to ovulation (Using a bull)

Answer 20

• 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

Question 21

Early lactation is usually characterized by …

Answer 21

NEB

Question 22

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

Answer 22

maintenance and lactation take priority overgrowth and reproduction

Question 23

NEB effect in fertility

Answer 23

fertility is impaired

Question 24

Body Condition Score (BCS)

Answer 24

Energy reserves of dairy cows

Question 25

Recommended BCS at calving = ...

Answer 25

3.5

Question 26

Recommended loss < 1 BCS from calving to ...

Answer 26

60 DIM

Question 27

> 1 BCS loss during the first 5 weeks of lactation

Answer 27

impaired fertility

Question 28

BCS range

Answer 28

1 (very thin) to 5 (extremely fat)

Question 29

The most frequent cause of nutritional infertility

Answer 29

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

Question 30

Protein

Answer 30

* 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

Question 31

Micronutrients

Answer 31

* Phosphorus is the most prevalent mineral deficiency affecting reproduction * The calcium/phosphorus imbalance has a similar effect

Question 32

Embryonic Loss

Answer 32

* 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

Question 33

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

Answer 33

30%

Question 34

Most cases (>90%) are ...

Answer 34

EED (within 42 d of insemination)

Question 35

How Can I short Cl ?

Answer 35

Early pregnancy diagnosis and early rebreeding

Question 36

Early detection of the nonpregnant cows is important for ...

Answer 36

early rebreeding

Question 37

Pregnancy Diagnosis

Answer 37

Progesterone assay Ultrasound (transrectal)

Question 38

Progesterone assay

Answer 38

* 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

Question 39

Ultrasound (transrectal)

Answer 39

* It is the method of choice for the early diagnosis of pregnancy in the cow * Accurate (99%)

Question 40

1st Ultrasound (transrectal) exam

Answer 40

26 - 28 d To detect non-pregnant cows

Question 41

2nd Ultrasound (transrectal) exam

Answer 41

56 d Because of high EEL

Question 42

Insemination is not recommended before ..... after calving

Answer 42

6 - 7 weeks

Question 43

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

Answer 43

7%