CaliBol® trial: Faster calcium uptake and more stable serum levels after calving

Trial name: Comparative calcium bolus trials for dairy cows (CaliBol® vs alternative bolus) 
Year: 2006 (Jan: Kansas farm trial • Nov: Fresno State University trial) 
Country / partners: USA: Cimarron Dairy Farm, Kansas (farm trial) and Fresno State Dairy Department, California State University (university trial) 

 
Around calving, calcium demand rises fast and that’s when the risk of milk fever and subclinical hypocalcaemia peaks. These two comparative trials were set up to document how quickly and how steadily calcium becomes available in the bloodstream when cows receive CaliBol® versus another commercial bolus (Product X). 

Both trials used the same practical protocol: two boluses per cow - one immediately after calving, and a second 12 hours later followed by repeated blood sampling to track serum calcium over the first 24 hours. 

Results

• Faster early calcium rise (Kansas farm trial): At 6 hours after the first bolus, serum calcium increased 12.0% with CaliBol® versus 8.6% with Product X.
• Higher serum calcium at 6 hours (Kansas): Average calcium reached 9.3 mg/dL with CaliBol® versus 8.8 mg/dL with Product X.
• Stable support through the risk window (Kansas): The second bolus helped maintain serum calcium as milk production increased later post-calving.
• More even calcium curve (Fresno State University): Jerseys given CaliBol® showed a more even serum calcium level than cows receiving Product X.
• Sustained release effect (Fresno State University): The trial notes that calcium propionate in CaliBol® helped sustain serum calcium levels for several hours after administration.

Conclusion

Across a commercial farm trial and a university trial, CaliBol® delivered a clear pattern: a stronger early rise in serum calcium and a steadier calcium curve through the first 24 hours after calving. For herds managing milk fever risk (especially in older cows and Jerseys) this supports CaliBol® as a practical post-calving tool to stabilise calcium availability when demand is highest.

Download the full trial documents below to see the full protocol, sampling schedule, and serum calcium curves: