This document discusses protocols for synchronizing estrus in cattle using various hormones. The main protocols described are: 1. Using a CIDR vaginal insert for 7 days along with a prostaglandin injection on day 6 to synchronize estrus in cows and induce estrous cycles in anestrous cows. 2. Ovsynch, Cosynch, and other protocols that involve GnRH and prostaglandin injections over 8-10 days to synchronize ovulation for timed artificial insemination. 3. For heifers, feeding MGA for 14 days to suppress estrus, then a prostaglandin injection 17 days after removing MGA to induce estrus in 2-5 days for breeding.

1. Estrous synchronization Protocol for non-cyclic animals
Synchronization of estrus (heat) involves manipulating the estrous cycle of dairy/beef cattle so they can
be bred at approximately the same time.
Products use to Synchronize Estrus in Beef/Dairy Cattle
Progestins:
CIDR Vaginal insert 2 In heifers and cows
MGA 0.5 mg/hd/day, oral In heifers
CIDR Contains 1.38 grams of progesterone in silicone, molded over a nylon spine.
MGA is approved for suppressing estrus in feedlot heifers to improve performance in animals intended
for slaughter.
GnRH:
Cystrolrelin 2 mL, IM/IV bovine females
Factrel 2 mL, IM/IV dairy females
Fertagyl 2 mL, IM/IV bovine females
These Products used to treat cystic follicles in beef and dairy cattle.

2. Protocols: (For Adults)
1. Synchronization of Estrus using the Vaginal Insert CIDR:
Estrous synchronization using the vaginal insert CIDR consists of placing the insert in the vagina on day
0, giving an injection of prostaglandin on day 6, and removing the vaginal insert on day 7 .Detect heat
from days 8 to 11 and inseminate all females that exhibit estrus. To assure satisfactory synchronization of
estrus, an injection of prostaglandin must be given to all females one day before the removal of the
vaginal insert. Removal of the insert on day 7 results in a drop in circulating plasma progesterone,
triggering estrus within 3-4 days. The progestin in the vaginal insert can induce estrous cycles in
anestrous cows and advance puberty in heifers. The majority of the females that respond to this protocol
will exhibit estrus between 25 and 72 hours after the prostaglandin injection.
2. OvSynch:
 Maximum No. of Injections = 3
 Maximum No. of Handling Periods = 4
 Duration of Protocol in Days = 10
 Recommended for Timed AI = Y es
 Breed Cows Showing Estrus Anytime During the Protocol
 CIDR could be used between GnRH and PG (7 days

3. 3. 48 Hour CoSynch :
 Maximum No. of Injections = 3
 Maximum No. of Handling Periods = 3
 Duration of Protocol in Days = 9
 Recommended for Timed AI = Y es
 Breed Cows Showing Estrus Anytime During the Protocol
 CIDR could be used between GnRH and PG (7 days)
4. 72 hours Cosynch:
 Maximum No. of Injections = 3
 Maximum No. of Handling Periods = 3
 Duration of Protocol in Days = 10
 Recommended for Timed AI = Y es
 Breed Cows Showing Estrus Anytime During the Protocol
 CIDR could be used between GnRH and PG (7 days)

4. 5. 56 hour Ovsynch:
 Maximum No. of Injections = 3
 Maximum No. of Handling Periods = 4
 Duration of Protocol in Days = 10
 Recommended for Timed AI = Y es
 Breed Cows Showing Estrus Anytime During the Protocol
 CIDR could be used between GnRH and PG (7 days)
For Heifers:
1. Using MGA &prostaglandin Protocol to Synchronize Estrus:
A low cost system for estrous synchronization uses Melengestrol Acetate (MGA) and
prostaglandin. MGA is a "progesterone-like" feed additive that suppresses estrus in
feedlot heifers. MGA is fed at 0.5 mg/head/day for 14 days. Females will exhibit estrus
2-5days after withdrawal of the MGA. The estrus that occurs immediately after MGA
feeding subfertile and females should not be bred on this estrus. A single injection of
prostaglandin is administered 17 (or 19 days) days after the MGA has been removed

5. from the feeding program. Most females will exhibit estrus 48 to 72 hours after the
prostaglandin injection. Inseminate females 12 hours after standing estrus. This
protocol is capable of inducing estrous cycles in some females that are not yet cycling.
Timed mating all females or those that have not yet displayed heat at 72 hours (heifers)
or 80 hours (cows) after the prostaglandin injection results in additional pregnancies
2. CIDR CoSynch:
 Maximum No. of Injections = 3 Plus CIDR Insertion & Removal
 Maximum No. of Handling Periods = 3
 Duration of Protocol in Days = 8
 Recommended for Timed AI = Y es
 Breed Cows Showing Estrus After CIDR Removal
 Resynch option: 13-14 days post AI insert CIDR, 7 days later remove CIDR and heat detect

6. 3. Pfizer CIDR:
 Maximum No. of Injections = 1 Plus CIDR Insertion & Removal
 Maximum No. of Handling Periods = 4
 Duration of Protocol in Days = 10 to 11
 Recommended for Timed AI = No
 Breed Cows Showing Estrus After CIDR Removal