Bovine Repro phys and synch programs

Question 1

How long is the estrous cycle of a cow?

Answer 1

21 days

Question 2

How long does estrus behavior last in dairy and beef cows?

Answer 2

Estrus lasts 24 hours, behavior lasts 7 hrs in dairy, 12-18 in beef

Question 3

How long is diestrus in cattle?

Answer 3

14 days

Question 4

How long is metestrus in cattle?

Answer 4

3-4 days
Period between estrus and diestrus (CH)

Question 5

How long is proestrus in cattle?

Answer 5

2-3 days

Question 6

What is day 0 of the cycle?

Answer 6

Estrus

Question 7

What is the role of prostaglandin?

Answer 7

It lyses the CL and shortens the luteal phase
-examples: lutalyse and estrumate

Question 8

Why are progestins used?

Answer 8

To lengthen the luteal phase
-they provide negative feedback on pituitary
-ex: CIDR

Question 9

When are GnRH agonists used?

Answer 9

They either reset the follicular wave or trigger ovulation by stimulating the release of LH/FSH from the anterior pituitary
ex: cystorelin

Question 10

What does GnRH do if there is a CL present vs when there is not one.

Answer 10

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

Question 11

What factors should be considered in protocol selection?

Answer 11

Cost of products used and labor, efficacy of the protocol, facilities, BCS of females, postpartum interval of cows, overall objective of producer

Question 12

What is the select-synch protocol

Answer 12

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

Question 13

What is the ovsynch protocol

Answer 13

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

Question 14

Where are CIDRs used more commonly- beef or dairy?

Answer 14

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.

Question 15

What are the benefits to OvSynch 48 compared to the other ovsynch protocols?

Answer 15

Can do everything at the same time everyday

Question 16

What are the pros to ovsynch 56?

Answer 16

More effective than the other ovsynch modifications- better results than ovsynch 56

Question 17

What is the benefit to using a secondary PGF 24 hours after the first in the ovSynch protocol?

Answer 17

Increases luteolysis and therefore fertility

Question 18

Describe the cosynch protocol

Answer 18

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

Question 19

What is CoSynch 72 equivalent to?

Answer 19

Select synch

Question 20

What is different with the 5 day CoSynch

Answer 20

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

Question 21

What are the benefits to 5 Day Cosynch + CIDR in beef?

Answer 21

Reduces time to AI (8 days vs 10)
-still extra handling time though

Question 22

What is added in a 7 and 7 Synch

Answer 22

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

Question 23

What is the presynch program used before TAI and why are they used?

Answer 23

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

Question 24

What is the double ovsynch protocol?

Answer 24

GnRH day 1, PGF day 7, GnRH day 10, wait 7 days then start timed AI program
-provides more accurate synchronization

Question 25

What is the purpose of resynchronization programs?

Answer 25

To get open cows bred back quicker

Question 26

What changes are made in beef heifer protocols?

Answer 26

14 day CIDR
- forces them to ovulate and form a CL
-5 days tend to work better for CIDRs