Missouri Dairy Business Update

Volume 13, Number 6
June 2013

MU Southwest Center Grazing Dairy - June Update

SW Center Parlor
By Dr. Stacey Hamilton, University of Missouri Extension

In a previous post, we described a current research trial where the University of Missouri Southwest Research Dairy was evaluating two different timed AI synchronization protocols for lactating dairy cows. In the past, the SWC has used the ShowMe Synch protocol with good results (greater than 55% cows pregnant to timed AI (TAI)). The ShowMe Synch program entails insertion of a CIDR for 14 days followed by a prostaglandin F2α injection 19 days after CIDR removal. Fifty-six hours after the prostaglandin F2α injection, GnRH injection is administered followed by insemination of all cows 16 hours after the GnRH injection.  Although this program has proven to work well as the SWC and other dairies as well, it takes 35 days to “set the cows up” prior to breeding and requires advanced planning for the program to work successfully.

In contrast, the CoSynch method only requires 10 days and requires less planning. This synchronization protocol requires the insertion of a CIDR for only 7 days along with a GnRH injection. After the CIDR is removed, prostaglandin F2α is administered followed by GnRH 56 hours later and timed insemination of all cows 16 hours after the GnRH injection.

In the table below results of the pregnancy results for each treatment are found. In both treatments over 60% of the cows were found pregnant to timed AI at day 25 post breeding using the IDEXX blood pregnancy test.  This demonstrates both programs worked equally well in getting cows pregnant in a timed mating situation.


# cows
Timed AI

# cows

% cows





Show Me Synch




In addition to the normal synchronization protocols, half of the cows in each treatment were placed on a re-synchronization protocol to determine if cows could be “re-synched” quickly if they failed to become pregnant to the original TAI. This could result if successful, in only breeding cows twice in 28 days without the need for heat detection. Results of this “re-synch” are pending and will be reported after the ultrasound pregnancy diagnosis checks in July.

For producers, dairy and beef alike, who wish to group calve in very tight windows an opportunity to increase the amount of pounds milk or weaned beef by increasing the days cows are milked in seasonal operations or age of calves in beef production systems.

For example, we project we will have 85% of our milk cows and heifers freshen within 7 days at the beginning of the calving season next year. This could add as much as 1,000 pounds of milk per cow on average for the milking season making the costs and time for the synchronization protocols well worth the investment.

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