Hidden cost of milk fever revealed

Milk fever and its less visible cousin, subclinical hypocalcaemia, can quietly strip thousands of dollars from even the best-managed herds through lost milk, extra labour, and preventable vet bills.

While most producers recognise milk fever’s tell-tale signs — downer cows, delayed recovery, or worse — it’s the hidden losses that do the most financial damage.

Research shows that for every clinical case, five cows may be subclinical.

These animals appear healthy, but often produce up to 30 per cent less milk, experience lower fertility, and are more prone to infection.

By the numbers: how milk fever drains profit

Let’s take a 100-cow herd as an example.

Most Australian herds will experience around five clinical milk fever cases per year.

At an average cost of $450 per case (including treatment, milk loss, and extended recovery), that’s roughly $2,250 in visible losses.

However, the greater impact comes from subclinical cases that go unnoticed.

Let’s look at how the longtail of milk fever affects a 100-head herd:

Step-by-step calculations

Clinical milk fever

5 cases × $450 = $2,250.00

Subclinical milk loss (per cow)

50 L/day × $0.75/L = $37.50/day (full production value)

30% of 50 L = 15 L/day lost → 15 L × $0.75 = $11.25/day lost

$11.25/day × 10 days = $112.50 lost per subclinical cow

Subclinical total (25 cows)

$112.50 × 25 = $2,813

Total impact per 100-cow herd

$2,250.00 (clinical) + $2,813 (subclinical) = $5,063

When you factor in lower fertility, retained membranes, and delayed recovery, the true financial toll easily exceeds $6,000 per 100 cows annually — and that’s before considering labour or stress.

Maintaining calcium balance in dairy cows

So, what’s driving these losses?

At calving, a cow’s demand for calcium skyrockets.

If her system can’t mobilise enough calcium from bone stores, blood calcium levels drop.

This leads not only to milk fever, but also slower calving, retained placenta, mastitis, and metritis.

Preventing calcium-related issues before calving is one of the most profitable management decisions a dairy farmer can make.

For family-run dairies, prevention is about peace of mind to reduce stress during one of the busiest times of year and freeing up time to focus on the herd as a whole.

For larger operations, it’s about consistency and efficiency: fewer interventions, smoother calvings, and a more predictable milk flow that supports contract supply.

Lachie Sutherland milks 400 Holstein cows in south-west Victoria.

“Since introducing Prelac, we had cows come into the dairy heavier and in better condition, we see them produce more, get in-calf earlier and we’ve also noticed hardly any retained foetal membranes.”

To reduce metabolic disease risk, smooth calving, and maintain consistent milk production year-round, a nutritional program that includes Prelac — designed to address calcium balance before calving — can help prevent long-term production losses.

How Prelac works

Unlike traditional dry cow mineral supplements, Prelac uses a targeted blend of ionic salts and hydrochloric acid to activate the cow’s natural calcium release mechanisms.

It works by slightly acidifying the blood (a process known as dietary cation-anion difference, or DCAD management), triggering a hormonal response that improves calcium absorption and mobilisation.

When calving begins and milk production starts, the cow’s body is already switched on to release calcium efficiently, reducing the risk of both clinical and subclinical hypocalcaemia.

Prelac also supplies key trace minerals to support post-calving recovery — helping the placenta separate cleanly, reducing infection risk, and supporting faster return to cycling and joining.

Another major advantage is 24-hour availability. Unlike powdered or bagged mixes that rely on hand feeding, Prelac’s liquid form ensures consistent intake even for shy feeders to help reduce labour and improve herd uniformity.

Building resilience in modern dairy systems

With rising costs, labour shortages and tighter production margins, Australian dairies can’t afford silent losses.

Proactive nutritional management is no longer just about preventing disease; it’s about protecting productivity and profit.

Producers using Prelac are seeing fewer metabolic issues, faster recovery, and stronger herd performance across the board.

It’s a simple, proven step that builds resilience in both the cow and the business.

Talk to your local nutrition specialist about Prelac — or request a free nutritional consult to understand how Prelac can protect fertility, milk flow and profit in your herd.