Lecture 1: Herd Health for Optimal Repro in Dairy Cattle (Risco)

Question 1

cull

Answer 1

removal from the flock

Question 2

reproductive efficiency a result of:

Answer 2

• days that a cow spends in the most efficient time of the lactation curve
• cull rate due to reproductive failure

Question 3

calving interval

Answer 3

period of time between 2 calvings

Question 4

peak milk production usually occurs ___ weeks post-partum

Answer 4

4 weeks

Question 5

voluntary waiting period (VWP)

Answer 5

period of time after parturition that YOU decide to wait and not re-breed cow (usually about 60 days)
Goal = maximize # of cows pregnant at end of VWP

Question 6

lowest milk production should be around what month of pregnancy?

Answer 6

7th

Question 7

cows that spend > 60 days in dry period have higher incidence of:

Answer 7

mastitis
metritis
ketosis
retained placenta

Question 8

dry period

Answer 8

period of time between when cow dries off (stops producing milk) and the next calving

Question 9

factors to optimize repro performance

Answer 9

• hormonal manipulation

- biological and management factors

Question 10

4 reproductive indices that determine the reproductive efficiency of a dairy herd

Answer 10

1) VWP
2) estrous detection rate
3) conception rate
4) pregnancy loss

Question 11

conception rate

Answer 11

proportion of cows that become pregnant of those seen in estrous and inseminated

Question 12

pregnancy loss

Answer 12

how many cows lose pregnancy from those that were in estrous, inseminated, and became pregnant (either by loate embryonic death or abortion)

Question 13

pregnancy rate =

Answer 13

# cows pregnant/# cows eligible to become pregnant in a 21 days cycle = EDR x CR = days at which cows become pregnnt past the VWP
-if high, more cows become preg. sooner at end of VWP

Question 14

vg. estrous cycle of cows

Answer 14

21 dys

Question 15

CR

Answer 15

conception rte

Question 16

EDR

Answer 16

estrous detection rate

Question 17

increasing PR –> calving to conception interval

Answer 17

dec.

Question 18

ideal preg. rate with one cycle

Answer 18

25% (avg. is 17% in U.S.)

Question 19

est. of preg. after parturition depends on:**

Answer 19

the anatomical and functional return of the genital tract to its pregravid state:
-involves uterine involution and early onset of ovarian cyclicity**

Question 20

2 components of uterine involution***

Answer 20

-reduction in size of uterus
-re-epithelization of inter caruncular endometrium (helps rid infection, which occurs in 80-90% of cows)
(onset of ovarian cyclicity facilittes involution via resolution of infection)

Question 21

ovarian cyclicity refers to:**

Answer 21

devel. of follicles (pre-ovulatory –> ovulate –> CH –> CL –> insemination –> CL regresses –> foll. growth and ovulation occur again)

Question 22

cows w/ prolonged ovarian cyclicity take longer/shorter to rid infection**

Answer 22

longer

Question 23

VWP allows for:

Answer 23

postprtum uterus to return to pre-gravid state for preg. to occur and be maintained

Question 24

ideal VWP

Answer 24

70-80 days pp

Question 25

when is uterine involution usually completed by?

Answer 25

42 days pp. Less than 25% of cows will have mild infection (endometritis) by end of 42-50 days (so waiting longer will reduce infection even more and risk of preg.)

Question 26

What strategies are used to correct and reverse low repro efficiency?

Answer 26

• improve env. for cow
• improve how employees deal with cows (i.e. prevention and therapeutic programs)
• min. pp dz to improve fertility
• nutrition
• repro management (i.e. OvSynch)

Question 27

transition cow

Answer 27

3 wks before and after parturition. More prone to problems during this time

Question 28

eutocia

Answer 28

normal calving (occurs about 60% of the time)

Question 29

pp diseases

Answer 29

metritis (bad)
Clinical endometritis
fever
mastitis
ketosis (worst)
lameness
pneumonia
digestive
*cows with these problems are at greater risk for subclinical ketosis and inflamm. problems
*also affects HPA axis

Question 30

days in milk =

Answer 30

days pp

Question 31

where does conception take place in cows

Answer 31

oviduct

Question 32

calf embryo recognized at __ days

Answer 32

17d

Question 33

main pp diseases in first 60 DIM

Answer 33

calving problem
metritis (bad)
clinical endometritis
fever pp
mastitis
clinical ketosis (worst)
lameness

Question 34

what determines when cows are first AI at the end of the VWP?

Answer 34

estrus detection rate (AI submission rate)