Why Calcium Actually Matters (And Why Most Boluses Fall Short)
Here's the thing with calcium boluses - most of them are designed to dissolve fast and hit the cow with a calcium spike. That's why they all tell you to "give another bolus at 12 hours" - because that's about as long as their calcium delivery lasts. The trials prove it.
Cow Start Complete works differently. The bolus matrix dissolves in two phases and carries a much higher calcium payload than standard boluses. Between the right calcium specification, the controlled dissolve rate, and how the calcium sources actually get absorbed, you get calcium delivery for a full 48 hours. That's why you only need one dose (2 boluses) straight after calving - job done.
THE DATA THAT BACKS THIS UP:
The first (published November 2024) from Anchor Life Sciences and vets at University College Dublin tested Cow Start Complete on 26 cows from a 280-cow pasture-fed Irish herd producing around 6,600kg per season (21L/cow/day). The results were clear: one dose of Cow Start keeps supplying calcium long after a short-acting bolus has packed it in. Another in 2025 (manuscript in preparation) confirmed what they saw in 2024.
THERE’S 2 PARTS TO THE PROBLEM. 1) THE ONE EVERY FARMER KNOWS: MILK FEVER
You know the routine. Your cow calves overnight or early morning. You collect her after the morning milking around 9AM, remove the calf, milk her, give her a bolus, and she goes into the colostrum mob. Job done. You head off to do the rest of the day's work.
But here's what's happening while you're not there - have a look at the graphic above, particularly those two blue shaded zones marked "Night 1" and "Night 2" (10PM-7AM).
The Real Timing Problem:
Most calcium boluses give you about 8-12 hours of protection. So if you dose her at say 9AM:
By later that evening, that calcium boost is wearing off
That first night (10PM-7AM) she's well below safe levels while you're asleep
Then she’s into the second night (10PM-7AM) with no extra support coming in.
And that second night? That's sitting smack in the middle of when 67% of milk fever cases actually happen
What the lines tell you:
Red line (1 bolus at 9AM): Watch what happens through both nights. Night 1 she's already dropping below the safe threshold. Night 2 (the darker red "PEAK RISK" zone) she's got nothing left and that's exactly when most cows go down. This is why you find down cows on that second or third morning.
Orange line (2 boluses): Even with a second dose at evening milking, the protection runs out well before that critical second night when 67% of cases occur.
Teal line (Cow Start Complete at 9AM): Stays well above the safe level through both Night 1 AND Night 2. One dose at morning milking on Wednesday keeps her protected through to Friday morning and beyond.
Why This Second Night Matters So Much:
The research is crystal clear: 31% of cases in the first 24 hours, but 67% on day two. Count it out from a 9AM bolus:
Day 1: Wednesday 9AM to Thursday 9AM (31% of cases)
Day 2: Thursday 9AM to Friday 9AM (67% of cases - Night 2 is right in the middle of this)
That second night is when you're most likely to have them go down so you need your calcium supplementation to still be working.
AND 2) THE ONE MANY FARMERS DON’T KNOW - SUBCLINICAL HYPOCALCAEMIA.
We know low calcium in those critical first days post-calving is linked to disease risk, poor immune function, energy problems, reduced rumination, and lower milk production. A short period of low calcium is normal and typically not an issue for a cow. However a few days of low calcium can affect the cow's entire season.
The numbers don't lie:
Subclinical hypocalcaemia causes a production loss (estimates vary from between 4 - 7%)
Clinical milk fever hits you with a 14% loss
A recent NZ study showed that between 60-80% of multiparous cows have low calcium immediately after calving, and around 30% are still low at day 3. It's these persistent subclinical cows that have the most issues down the track and they are the ones we need to target. The simple fact is this: for most farms in NZ subclinical hypocalcaemia is actually the bigger financial burden, because it affects many cows in the herd. However you don’t see it, and so you accept the trajectory your herd is on as “normal”. Our data shows what happens when you address the issue.
References:
Wilms, J. et al. Journal of Dairy Research 2022, Vol. 89, (1), pp 29-36
Verhoef, W. et al. Veterinary Medicine: Research & Reports 2021, 12, pp 23-32
Martinez, N. et al. J. Dairy Sci. 2016, Vol. 99, (10) pp 8397 - 8416
Lawlor, J. et al. Animal & Veterinary Sciences 2024 Vol. 12, (6), pp 154-160.
Fahey, A., Lawlor. J., Cow Start Research Meta-analysis, 2022
Goff, J P. et al J. Dairy Sci. 2020, Vol. 103: 2591 - 2601
Dairy NZ/Milk-Fever
Roberts, K I., et al. New Zealand Vet Journal 2018