DSD 5.3 | Slight modifications of CIDR Sync - help or hinder? In this time of heifer inventory shortage – getting heifers pregnant (in a timely fashion) is even more important than ever. Contract heifer growers in California sought the help of Dr. Fabio Lima and his team at UC Davis to best understand the use of a 6-day CIDR sync with variable rates of GnRH could increase pregnancies when bred to sexed semen. The findings we discuss are published in the recently released Journal of Dairy Science article titled: Effect of 200 μg of gonadorelin hydrochloride at the first GnRH of a CIDR Synch program on  ovulation rate and pregnancies per AI in Holstein heifers. Listen in to hear the results and nuanced details of controlling reproductive structures using timed AI protocols. Topics of discussion 1:03       Production costs of heifer rearing - survey results 2:09       Introduction of Dr. Fabio Lima 3:46       Description of the project 4:20       TAI protocol description5:31       Varying GnRH dose6:34       What is the function of GnRH in the heifer? 7:51       Hallmark of a successful synchronization 8:24       Results of ultrasound (ovulation) and P4 blood sample analysis 10:04    Did increased ovulation translate into improved pregnancy outcome? 10:44    Pregnancy at d47, 100% sex semen discussion13:41    Relationship of Luteinizing hormone and progesterone 15:16    What causes elevated circulating progesterone 16:30    How did we land on 2cc of GnRH to begin with? 18:34    Does increased GnRH cause increased twinning?              21:02    What do you want boots on the ground dairymen to know23:01    What if you cherry picked? 23:32    Sometimes the plan doesn’t work – but that’s why we do research! Featured article: Effect of 200 μg of gonadorelin hydrochloride at the first GnRH of a CIDR Synch program on  ovulation rate and pregnancies per AI in Holstein heifers Articles also discussed in the podcast:Heifer study using 100 and 200 ug in 5-d CIDR Synch protocol. https://doi.org/10.1016/j.theriogenology.2023.04.026 Studies showing the implication of progesterone for double ovulation (a proxy for twining) and progesterone. https://doi.org/10.3168/jds.2018-14410       #2xAg2030; #journalofdairyscience; #openaccess; #MODAIRY; #gnrh; #CIDRsync; #twinning; #pregnancy; #heiferdevelopment; #TAI; #lutenizing; #dairysciencedigest; #ReaganBluel;