Exam 3 Flashcards
what is the goal of estrous synchronization?
control estrus and ovulation in females so that breeding can be completed in a short period of time
Non synchronized estrus
50% get bred each cycle and with 3 cycles 88% are bred
Synchronized estrus
1 extra cycle equals 94% cows are pregnant
Advantage of average cow age with synchronized estrus
9 day advantage & 6% total pregnancy rate advantage utilizing a timed breeding program and assuming 50% AI and Natural Service conception rates
Potential advantages of estrous synchronization
-can shorten breeding and calving season
-shortened time to breeding
-utilizes labor more efficiently
-no heat checking needed
-reduced days to first service
-groups timing of parturition which means uniform offspring
What regarding cost is a disadvantage in estrous synchronization
-labor costs are increased because it requires specifically skilled labor
-much higher input costs so need to way risks and rewards
What regarding labor is a disadvantage in estrous synchronization
requires skilled labor and periods of intensive management
-multiple injections are needed
What regarding facilities is a disadvantage in estrous synchronization
-requires adequate facilities
-less time is spent observing animals
-can miss detecting non-cyclers in herd
How does prostaglandin manipulate the cycle
-decrease progesterone
-regresses cl
Restraints on prostaglandins regressing active corpus luteum
-only effective on day 5-17 corpus luteum
-no effect on days 0-5
-days 18-20 there is no corpus luteum
Hoe do progestins manipulate the cycle
blocks ovulation
How soon after PGF2a injection does the animals go into estrus
usually 2-5 days
heifers 50hrs
cows 72hrs
How many PGF2a injections need to be given
If one about 60-65% will respond
If two you will sybncronize the entire herd as the ones who did not respond will be in the luteal phase
Factors to consider with PGF2a
-animals must be cycling
-easy to use
cost 1-3$ per dose
can be combined with GnRH for timed AI
Synchronization with PGF2a
-Inject PGF on day 0
-heat check and AI days 2-7
-Inject PGF on day 12-14
-heat check and AI days 2-7
The goal of progesterone when synchronizing estrus
suppress estrus by reducing GNRH pulses thus preventing the preovulatory LH surge and also blocks behavioral estrus
Progesterone Administration for livestock species
Injection
Feed-mix in the ration
Implant-place in ear
CIDR-place in vagine
Effectiveness of the CIDR
-extremely effective and works within the hour
-while inside maintains
-once removed progesterone levels drop within 4 hours since no CL
MGA-melengesterol acetate
form of progesterone
cheapest (pennies per day)
oral administration in food
MGA disadvantages
-cows have to have supplemental feed
-they have to be fed this for a long time to make sure each cow gets enough especially the submissive cows
Norgestemate
-ear implant
-no longer on market for livestock
-too challenging and invasive
CIDR advantages
easy to use
multiple inserts can be used to alter therapeutic levels
retention rates about 95%
Recommendations for using CIDR
-implant for 7 days (enough to mimic the luteal phase)
-inject PGF on day 6 or day 7
-heat check and breed after heat for the next 3-4 days after CIDR removal
OV-Synch GNRH
On day 0-follicle turnover
(85% of cows will ovulate follicle but all will start new follicular wave)
Day 8-9 regresses CL