College - Author 1

College of Agriculture, Food and Environmental Sciences

Department - Author 1

Dairy Science Department

Degree Name - Author 1

BS in Dairy Science



Primary Advisor

Stan Henderson


The objective of this study was to determine the success of a presynchronization program implemented on a modern dairy facility. The study was conducted on a 1,400 cow dairy in the central valley of California. 86 cows were involved in the study during the summer months of June through September. Cows were either assigned in the synchronization program or placed in a control group based on the last digit of their identification. At 43 DIM, presync cows were injected with their first treatment of the synchronization program. Estrous cycles of the presync group were manipulated with treatments of Prostaglandin and GnRH. Treatments were applied so that cows had a predetermined breeding date between 60 and 81 days after calving. Detection of estrous was performed daily with tail paint removal being the primary method of detection for the control group. The control group was eligible for insemination once reaching the 60 day voluntary waiting period. First service conception rates for the synchronized and control groups were 31% and 37% respectively, while the 21 day pregnancy rate for synchronized animals were 19% and 14%. With a 5% difference, the presynchronization program appears to be more successful in achieving higher reproductive efficiency.

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Dairy Science Commons