Bovine Repro phys and synch programs Flashcards
How long is the estrous cycle of a cow?
21 days
How long does estrus behavior last in dairy and beef cows?
Estrus lasts 24 hours, behavior lasts 7 hrs in dairy, 12-18 in beef
How long is diestrus in cattle?
14 days
How long is metestrus in cattle?
3-4 days
Period between estrus and diestrus (CH)
How long is proestrus in cattle?
2-3 days
What is day 0 of the cycle?
Estrus
What is the role of prostaglandin?
It lyses the CL and shortens the luteal phase
-examples: lutalyse and estrumate
Why are progestins used?
To lengthen the luteal phase
-they provide negative feedback on pituitary
-ex: CIDR
When are GnRH agonists used?
They either reset the follicular wave or trigger ovulation by stimulating the release of LH/FSH from the anterior pituitary
ex: cystorelin
What does GnRH do if there is a CL present vs when there is not one.
If no CL, promotes ovulation of the dominant follicle and leads to emergence of a new wave in 1.5-2 days
If CL present, it promotes follicle turnover and the development of a new cohort of follicles
What factors should be considered in protocol selection?
Cost of products used and labor, efficacy of the protocol, facilities, BCS of females, postpartum interval of cows, overall objective of producer
What is the select-synch protocol
GnRH on day 1, PGF 7 days later when CIDR is removed (if using), heat detection and AI at 6-13 days
-start estrus detection at day 6 if no CIDR-should give GnRH and TAI to all non-responders 72-84 hrs after PGF
What is the ovsynch protocol
GnRH on day 0, PGF 7 days later, GnRH again 2 days after that, then breed 8-18 hrs later
-commonly used in dairy cows
Where are CIDRs used more commonly- beef or dairy?
Beef! As it limits time they need to be handled and you are breeding them all as a group. Dairy are easy to breed again if need be.
What are the benefits to OvSynch 48 compared to the other ovsynch protocols?
Can do everything at the same time everyday
What are the pros to ovsynch 56?
More effective than the other ovsynch modifications- better results than ovsynch 56
What is the benefit to using a secondary PGF 24 hours after the first in the ovSynch protocol?
Increases luteolysis and therefore fertility
Describe the cosynch protocol
GnRH on day 0, PGF 7 days later, GnRH and AI 54-66 hrs later
-commonly used in beef due to less handling times
-often add on CIDR
What is CoSynch 72 equivalent to?
Select synch
What is different with the 5 day CoSynch
PGF 5 days after GnRH and again 24 hours later, then 48 hrs later do GnRH and TAI
-used more for dairy since adding in another handling time
What are the benefits to 5 Day Cosynch + CIDR in beef?
Reduces time to AI (8 days vs 10)
-still extra handling time though
What is added in a 7 and 7 Synch
Used in beef cows
-CIDR is in for 14 days. Start PG at same time as CIDR insertion
-GnRH at day 7
-essentially a Cosynch after day 7
-essentially a presynch and cosynch protocol combined
What is the presynch program used before TAI and why are they used?
PGF 2 times 14 days apart, then estrus detection and AI for 2 weeks before timed AI program
- used in dairy
-all should be close to undergoing luteolysis at the start of the TAI program
What is the double ovsynch protocol?
GnRH day 1, PGF day 7, GnRH day 10, wait 7 days then start timed AI program
-provides more accurate synchronization
What is the purpose of resynchronization programs?
To get open cows bred back quicker
What changes are made in beef heifer protocols?
14 day CIDR
- forces them to ovulate and form a CL
-5 days tend to work better for CIDRs
