Lecture 1: Herd Health for Optimal Repro in Dairy Cattle (Risco) Flashcards
cull
removal from the flock
reproductive efficiency a result of:
- days that a cow spends in the most efficient time of the lactation curve
- cull rate due to reproductive failure
calving interval
period of time between 2 calvings
peak milk production usually occurs ___ weeks post-partum
4 weeks
voluntary waiting period (VWP)
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
lowest milk production should be around what month of pregnancy?
7th
cows that spend > 60 days in dry period have higher incidence of:
mastitis
metritis
ketosis
retained placenta
dry period
period of time between when cow dries off (stops producing milk) and the next calving
factors to optimize repro performance
- hormonal manipulation
- biological and management factors
4 reproductive indices that determine the reproductive efficiency of a dairy herd
1) VWP
2) estrous detection rate
3) conception rate
4) pregnancy loss
conception rate
proportion of cows that become pregnant of those seen in estrous and inseminated
pregnancy loss
how many cows lose pregnancy from those that were in estrous, inseminated, and became pregnant (either by loate embryonic death or abortion)
pregnancy rate =
# 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
vg. estrous cycle of cows
21 dys
CR
conception rte
EDR
estrous detection rate
increasing PR –> calving to conception interval
dec.
ideal preg. rate with one cycle
25% (avg. is 17% in U.S.)
est. of preg. after parturition depends on:**
the anatomical and functional return of the genital tract to its pregravid state:
-involves uterine involution and early onset of ovarian cyclicity**
2 components of uterine involution***
-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)
ovarian cyclicity refers to:**
devel. of follicles (pre-ovulatory –> ovulate –> CH –> CL –> insemination –> CL regresses –> foll. growth and ovulation occur again)
cows w/ prolonged ovarian cyclicity take longer/shorter to rid infection**
longer
VWP allows for:
postprtum uterus to return to pre-gravid state for preg. to occur and be maintained
ideal VWP
70-80 days pp
when is uterine involution usually completed by?
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.)
What strategies are used to correct and reverse low repro efficiency?
- 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)
transition cow
3 wks before and after parturition. More prone to problems during this time
eutocia
normal calving (occurs about 60% of the time)
pp diseases
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
days in milk =
days pp
where does conception take place in cows
oviduct
calf embryo recognized at __ days
17d
main pp diseases in first 60 DIM
calving problem metritis (bad) clinical endometritis fever pp mastitis clinical ketosis (worst) lameness
what determines when cows are first AI at the end of the VWP?
estrus detection rate (AI submission rate)
