University of Minnesota Beef Improvement Federation How to Get Cows Pregnant for the Purebred and Commercial Sectors of the Beef Industry – Using GnRH and CIDRs Cliff Lamb University of Minnesota Beef Improvement Federation July 2005

Estrous Synchronization and AI Natural Service vs. Estrous Synchronization and AI

Cost ($) per Pregnancy of Various Estrous Synchronization Protocols Herd size Protocol 30 hd 100hd 300hd Natural Service 58 35 35 MGA-PGF 62 41 37 MGA Select 66 45 41 MGA Select – TAI 70 51 48 Select Synch 68 46 41 CO-Synch 70 51 47 PGF-CIDR 73 51 47 CO-Synch+CIDR 80 61 55 Select Synch+CIDR 76 55 51 (Johnson and Jones, 2004)

Advantages of Natural Service and Artificial Insemination Cost Hassle factor Labor Time Good bulls at reasonable price Genetic Improvement Proven sires Shorten breeding season Shorten calving season Uniform calf crop Induce cyclicity

Effect of Postcalving Feed on Postpartum Estrus (Short et al., 1988)

Effect of Body Condition on Cyclicity Body condition score (Stevenson et al., 2004)

Effect of Parity and Body Condition on Ovulation Rates Body condition score (Stevenson et al., 2004)

Effect of Days Postpartum on Cyclicity Body condition score (Stevenson et al., 2004)

Estrous Synchronization Protocols Hybrid Synch Two shot PGF MGA/PGF Select Synch 7-11 Synch MGA Select Hybrid Synch+CIDR Ov-synch Presynch Resynch CIDR/PGF One shot PGF CO-synch Heat Synch CO-synch+CIDR

CIDR and GnRH Based Protocols

Concentrations of Progesterone in Ovariectomised Cows Produced by CIDR Containing 1.9g and 1.38g Progesterone Over a 20 Day Treatment ( = CIDRÒ1900 Cattle insert,  = CIDRÒ1380 Cattle insert, N = 10, error bars = SEM)

CIDR Protocols in Heifers

CIDR-PG & TAI Select Synch+ CIDR & TAI CO-Synch+CIDR CIDR-PG+TAI TAI & GnRH PGF CIDR CIDR-PG & TAI Detect estrus & AI TAI & GnRH GnRH PGF CIDR Select Synch+ CIDR & TAI Detect estrus & AI TAI & GnRH GnRH PGF CIDR CO-Synch+CIDR TAI & GnRH PGF CIDR CIDR-PG+TAI -18 to -16 -7 0 60 84 B B Days relative to PGF Hours relative to PGF

Effect of Location on Pregnancy Rates

First Service Pregnancy Rates 282/517 n = 289/504 n = 282/531 n = 258/525 Treatments

Pregnancy Rates after Estrus Detection Alone vs TAI 57.3 54.5 53.1 49.1 Treatment P = 0.221

CIDR-PG & TAI Select Synch+ CIDR & TAI TAI & GnRH PGF CIDR Detect estrus & AI TAI & GnRH GnRH PGF CIDR Select Synch+ CIDR & TAI Detect estrus & AI -7 0 60 84 Days relative to PGF Hours relative to PGF

Distribution of estrus as a percentage of all heifers treated 58% 61% Hours after PGF

Hours from PGF to Estrus Treatments

CIDR Protocols in Cows

CO-synch vs. CO-synch+CIDR TAI & GnRH GnRH PGF CO-Synch TAI & GnRH GnRH PGF CIDR CO-Synch+CIDR -7 0 48 Days relative to PGF Hours relative to PGF (Lamb et al., 2001)

First Service Pregnancy Rates Treatments

Effect of BCS on Pregnancy Rates Body condition score (Lamb et al., 2001)

Select Synch+CIDR & TAI GnRH PGF CIDR CIDR-PG & TAI Detect estrus & AI TAI & GnRH GnRH PGF CO-Synch TAI & GnRH GnRH PGF CIDR CO-Synch+CIDR TAI & GnRH GnRH PGF Select Synch & TAI Detect estrus & AI TAI & GnRH GnRH PGF CIDR Select Synch+CIDR & TAI Detect estrus & AI -18 to -16 -7 0 60 84 B B Days relative to PGF Hours relative to PGF

Effect of Location on Pregnancy Rates Locations

First Service Pregnancy Rates x x x x b n = 266/506 n = 238/548 n = 290/539 n = 269/507 n = 289/498 Treatments P < 0.05

Pregnancy Rates after Estrus Detection Alone vs TAI 58 53 54 53 43 b a c a,b b Treatment P < 0.05

Effect of Days Postpartum on Pregnancy Rates

Characteristics of Estrus TAI & GnRH PGF CIDR CIDR-PG & TAI Detect estrus & AI TAI & GnRH GnRH PGF Select Synch & TAI Detect estrus & AI TAI & GnRH GnRH PGF CIDR Select Synch+CIDR & TAI Detect estrus & AI -7 0 60 84 Days relative to PGF Hours relative to PGF

Distribution of estrus 52% 47% 57% Hours after PGF

Hours from PGF to Estrus and AI

Calving Distribution after Synchronization of Estrous

Calving Characteristics Gender ratio Treatment Gestation length AI calves Clean-up bulls PGF-CIDR &TAI 281.2 0.54 0.51 CO-Synch 281.8 0.49 0.50 CO-Synch+CIDR 282.2 0.50 0.57 Select Synch & TAI 281.7 0.57 0.47 Select Synch+CIDR & TAI 281.9 0.53 0.54 Overall 281.7 0.53 0.52 Overall births 994 841 635

Recommendations (for optimum PR) - Estrus Detection Cows and Heifers TAI & GnRH GnRH PGF CIDR Detect estrus & AI -7 0 72- 84 Days relative to PGF Hours relative to PGF Select Synch+CIDR & TAI

Recommendations (for optimum PR) - Timed AI TAI & GnRH GnRH PGF CIDR Heifers -7 0 54 - 60 TAI & GnRH GnRH PGF CIDR Cows -7 0 60 - 66 Days relative to PGF Hours relative to PGF CO-Synch+CIDR

Additional Considerations for Cattlemen Estrous Synchronization for bull breeding herds Resynchronization of estrus for non- pregnant cows Consider fixed-time AI Work with experts to define reproductive management procedures