Bovine Breeding Programs Flashcards
what is the biological minimum voluntary waiting period
50 days
is estrus detection a challenge in the dairy industry
yes, a big one
do cows and heifers have the same amount of estrus events and length of duration
No. Heifers have a longer duration and more events compared to multiparous animals. nearly double the amount of events
is there a difference in estrus behaviour between low producers vs high producers
technically yes, but its a trivial difference
what proportion of cows presented for AI that arent in heat when using visual detection
~17%
what proportion of cows presented for AI that arent in heat when using observation of standing only
5%
what proportion of cows presented for AI that arent in heat when using tail chalk
6% but there is a decent range (0-14%)
what proportion of cows presented for AI that arent in heat when using only secondary signs in tie stalls
22%
what proportion of cows presented for AI that arent in heat when using activity meters
4-9%
what is the “gold standard” for heat detection in cows
standing heat
what is most easily manipulated in cows?
insemination risk
what is insemination risk
proportion of eligible cows detected in heat. AI submission rate
what is conception risk
probability that AI results in pregnancy or proportion of breedings that result in dx of pregnancy
=pregnancy per AI
what is 21 day pregnancy risk
roughly = heat detection rate x conception risk
the proportion of open cows that become pregnant every 21 days
is heat detection always necessary?
not always if you are using synchronization
what does GnRH cause release of
LH and FSH
what are the effects of LH
causes ovulation of mature dominant follicles
what is the purpose of progesterone
-prevents an LH surge (ovulation) and sensitizes the brain to estrogen to allow for an LH surge later (when P4 is low)
what hormone supports embryo growth
progesterone
PGF, GnRH and P4 are _____
naturally occuring
what is the half life of PGF
minutes
where does prostaglandin come from naturally
endometrium
is giving hormones bad for the cow
not if its within physiological limits
what does it mean if a cow “no shows”
cant see the heat she is demonstrating
what is important to remember about heat and confinement of tie stalls
you will never see her in standing heat because no other cows will be available to mount her
what can affect heat detection? (8)
-intensity (of looking)
-accuracy (actually seeing it)
-confinement
-lameness
-flooring (if slippery)
-cow comfort
-severe or prolonged NEB
-repro tract dz
what is the lifespan of the ovum
6-8 hours - super short
what is the relationship between time sperm arrives and capacitation to fertilization
first sperm will reach egg in 3-4 hours but capacitation take 8-10 hours so the sperm that arrives the fastest are not the ones to impregnate the cow
what is the single weakest link in the process of getting a cow pregnant
heat detection!
what is involved in estrus synchronization (overview)
-prostaglandin shots to individual cows
-scheduled prostaglandin shots to groups
what % of cows are detected with activity monitors per cycle
60-80%
what is an example of a mount detector
tail paint
what is a pro of using tail paint
can have detection without having to keep an eye on them 24/7
what is the accuracy of rectal palpation for functional CL
75%
what is the accuracy of ultrasound scanning
90%
when is the CL responsive to prostaglandin
on day 7 of the 21 day cycle
when is a CL naturally lysed
day 18 of 21
if you give prostaglandin to a group of cows without knowing where they are in their cycle, what % will show an apparent estrus response
~2/3
50% due to the shot and 16% due to her own natural prostaglandin being present
does prostaglandin do anything to the follicles
no
why is there a variable time of ovulation after prostaglandin is given
she may have had a dominant follicle ready so ovulation <2 days
or she may have a small follicle that needs a bit more time to be ovulated so 2-5 days
does prostaglandin allow for timed AI
no because it has no control on the follicles
what is a pro of controling when a cow ovulates
you know when to inseminate her and you dont need to see heat
why is GnRH critical on day 1 of an ovsynch program
it stimulates LH…. which is critical to initiate a new follicular wave and ensure a new dominant follicle is ready by day 10!!
what are the steps in an ovsynch protocol
- give GnRH on day 1
- give prostaglandin shot at AM milking of day 7
- give GnRH shot at PM milking on day 9
- BREED in the morning on day 10
what is the length of time needed between each step of the ovsynch protocol
-between step 1 and 2 = 1 WEEK
-between step 2 and 3 = 48-56 HOURS
-between step 3 and 4 = 12-16 HOURS
what are the critical control points for optimizing an ovsynch protocol (5)
-start new follicular wave after 1st GnRH
-ovulate after 1st GnRH
-luteolysis after prostaglandin
-ovulation after 2nd GnRH
-insemination 16hours after 2nd GnRH
when is it best to start an ovsynch protocol
approx 1 week after a heat so you can get an extra CL (better fertility)
what happens if you ovsynch 1-4 days after heat
failure of synchronization of new follicular wave
what happens if you ovsynch 13-17 days after heat
spontaneous luteolysis and ovulation before timed AI
what happens if you ovsynch 18-21 days after heat
unresponsive CL at time of PGF
what is the best program for farms
whatever one gets done correctly and consistently
why would you pre-synch a cow
pre sync the estrus cycle so that cows are 6-7 days after an ovulation at the start of an ovsync
what do you do for a normal presync
-2 prostaglandin shots 14 days apart
-do it 11-14 days before you start ovsync
what do you do for double ovsync
- ovsync but dont AI, wait a week and then ovsync again and AI at the end
what does pre-synching achieve
increases the probability of pregnancy with an ovsync program by optimizing response to elements of the program
what is the purpose of inserting a CIDR (3 outcomes)
-prevents ovulation in cyclic cows
-stimulates ovulation in anestrus cows
-stimulates turnover in cystic cows
what happens when a CIDR is in for more than 14 days
produces persistent dominant follicle with decreased fertility
when would you use an ovsynch and CIDR impant protocol
for treatment of anovular animals and cystic ovarian condition
when do you insert the CIDR in an ovsync/P4 protocol
insert after you give the first GnRH shot, leave in for a week and take out once you give the prostaglandin shot
