Recommended protocols

With the rapid development of multiple protocols, the need arose to establish a common nomenclature and to facilitate transfer of the latest research into information to producers. Based upon these needs two organizations developed: Dairy Cattle Reproduction Council and Beef Reproduction Task Force. These groups consist of industry leaders, educators, researchers, veterinarians, and pharmaceutical representatives. These individuals come together to provide recommendations on reproductive technologies and synchronization protocols for their respective industries. Since this review is primarily focused for beef, the current synchronization protocols will cover those recommended by the Beef Reproduction Task Force and published by Johnson et al. (2013).

2.5.2.1 Heat detection protocols

Animals within the heat detection protocols will display peak estrus

approximately 48 to 72 h after PGF2α injection (Lauderdale, 1972). To accurately detect this estrus, heat detection must occur at minimum three times per day for a total

minimum time period of 3 h (Johnson et al., 2013). Animals detected in estrus should be AI approximately 6 to 12 h post first detected standing estrus.

1 Shot PG. Recommended for heifers. Animals within this protocol should undergo estrus detection and AI from d 0 through d 12 of the protocol. Animals not exhibiting estrus by d 5 should receive an injection of PGF2α.

Select Synch. Recommended for cows. Animals within this protocol will receive injections of GnRH on d 0 and PGF2α on d 7. Animals should undergo estrous detection and AI from d 6 though d 13 of the protocol.

Select Synch + CIDR. Recommended for cows. Animals within this protocol will receive a GnRH injection and CIDR insertion on d 0 and injection of PGF2α and removal of CIDR on d 7. Animals in this protocol should undergo estrus detection and AI from d 7 through d 13 of the protocol.

7-d CIDR-PG. Recommended for heifers. Animals within this protocol will receive a CIDR on d 0, followed by removal and injection of PGF2α on d 7. Animals should

undergo estrus detection and AI from d 7 through d 13 of the protocol.

PG 6-d CIDR. Recommended for cows. Animals within this protocol will receive PGF2α injection on d 0 followed by GnRH injection and CIDR on d 3. Removal of the CIDR occurs on d 9 with concurrent injection of PG. Animals should undergo estrus detection and AI from d 0 through d 3 and d 9 through d 12. Animals undergoing AI prior to CIDR insertion should discontinue the remainder of the protocol.

MGA-PG. Recommended for heifers. Animals within this protocol will be fed 0.5 mg of MGA from d 1 through d 14, followed by PGF2α injection 19 d later, or on d 33 of the protocol. Animals should undergo estrus detection and AI from d 33 through d 39 of the protocol.

2.5.2.2 Heat detection & timed artificial insemination protocols

Animals within the heat detection and TAI protocols will undergo estrus detection and AI for approximately 3 d, followed by AI of all animals not exhibiting estrus on at a predetermined time point with concurrent injection of GnRH in those animals (Johnson et al., 2013).

Select Synch & TAI. Recommended for cows. Animals within this protocol will receive injections of GnRH on d 0 and PGF2α on d 7. Animals should undergo estrus detection and AI for 72 to 84 h after PGF2α injection followed by TAI and GnRH injection on animals not exhibiting estrus.

Select Synch + CIDR & TAI. Recommended for cows and heifers. Animals within this protocol will receive a GnRH injection and CIDR on d 0 and injection of PGF2α and removal of CIDR on d 7. Animals should undergo estrus detection and AI for 72 to 84 h after PGF2α injection followed by TAI and GnRH injection on animals not exhibiting estrus.

PG 6-d CIDR & TAI. Recommended for cows. Animals within this protocol will receive PGF2α injection on d 0 followed by GnRH injection and CIDR insertion on d 3. Removal of the CIDR occurs on d 9 with concurrent injection of PG. Animals should undergo estrus detection and AI from d 0 through d 3 and 72 to 84 h after PGF2α injection followed by TAI and GnRH injection on animals not exhibiting estrus. Animals undergoing AI prior to CIDR insertion should discontinue the remainder of the protocol.

MGA-PG & TAI. Recommended for heifers. Animals within this protocol will be fed 0.5 mg of MGA from d 1 through d 14, followed by PGF2α injection 19 d later, or on d 33 of the protocol. Animals should undergo estrus detection and AI for 72 to 84 h after PGF2α injection followed by TAI and GnRH injection on animals not exhibiting estrus.

14-d CIDR-PG & TAI. Recommended for heifers. Animals within this protocol will receive a CIDR on d 0 with removal occurring on d 14. Animals will receive and injection of PGF2α 16 d later, or on d 30 of the protocol. Animals should undergo estrus detection and AI for 70 to 74 h after PGF2α injection followed by TAI and GnRH injection on

animals not exhibiting estrus.

2.5.2.3 Fixed timed artificial insemination protocols

All animals in FTAI protocols will not be heat detected for estrus and will

undergo AI insemination at a predetermined time point concurrent with an injection of GnRH (Johnson et al., 2013). All animals subjected to FTAI should be inseminated within

a 3 to 4 h period with the approximate average time of AI being equivalent to the listed time in the protocol.

7-d CO-Synch + CIDR. Recommended for cows and heifers. Animals within this protocol will receive a CIDR and injection of GnRH on d 0 followed by removal of the CIDR with concurrent injection of PGF2α on d 7. Cows should undergo FTAI and injection of GnRH 60 to 66 h after injection of PGF2α. Heifers should undergo FTAI and injection of GnRH approximately 54 h after injection of PGF2α.

5-d CO-Synch + CIDR. Recommended for cows. Animals within this protocol will receive a CIDR and injection of GnRH on d 0 followed by removal of the CIDR with concurrent injection of PGF2α on d 5 and a second injection of PGF2α 8 h later. Animals should undergo FTAI and injection of GnRH approximately 72 h after injection of the first PGF2α. Interval between first PGF2α injection and FTAI should be shortened to