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Why Minimum Inhibitory Concentrations (MICs) Matter  

When a cow has mastitis, you want the treatment that’s most likely to work, first time. MIC data helps you do exactly that. It shows which antibiotic is the most effective against the specific bacteria causing the infection in your cow, in your herd. Not a textbook average, not a guess, but real evidence from that cow’s sample. That means faster cures, fewer wasted treatments, and better protection of antibiotic effectiveness for the future. 

What MIC Actually Means 

The Minimum Inhibitory Concentration (MIC) is the lowest concentration of an antibiotic needed to effectively inhibit bacteria from growing.  

Think of it as a “potency” or “strength test”: 

• Low MIC value = the bacteria are easier to stop with that antibiotic 

• High MIC value = the bacteria are harder to stop with that antibiotic 

This data helps you pick the antibiotic most likely to be effective, first-time, every-time. 

How can I get MIC data? 

Laboratories routinely conduct MIC tests, and your vet might request this data on a problematic mastitis sample that is sent to the laboratory for analysis. Typically these results will take 48-72 hours to return a result to you.  

Mastatest puts this knowledge in your hands, on farm, no lab required, and within 24 hours. The unique Mastatest cartridge system enables us to identify the bacteria causing the infection, and in parallel, measures the MIC value for 3-6 common mastitis antibiotics.  

In your Mastatest results, you’ll get a list of the MIC values for those antibiotics tested in your cartridge. This list is ranked from the lowest MIC value (i.e. best chance of treatment success) to highest MIC value (lowest chance of treatment success). 

How to Interpret an MIC Value 

A lower MIC means the antibiotic is more potent against that specific bug. So if Antibiotic A has a much lower MIC than Antibiotic B, Antibiotic A is the better bet. 

You don’t need to memorise numbers – your Mastatest results rank the test results for you. But understanding the principle helps you make confident, evidence‑based decisions. 

Why don’t other mastitis diagnostics include MIC values? 

MIC data typically requires a laboratory to run multiple serial dilution experiments simultaneously on a milk sample. This is complex, and requires laboratory-level expertise.  

With Mastatest, the unique cartridge system automatically does all this work, with no added effort, at the same time as identifying the bacteria type in the sample. No lab skills are required – just pour the sample in, close the lid, and start the test. Results arrive in your inbox within 24 hours. 

Why MIC Data Is Valuable on Farm? 

1. Tailored to your herd 

MIC results are determined for the actual bacteria in your cows, not assumptions based on academic data. You get a picture of what’s happening in each individual case and across the herd. 

2. Better treatment outcomes 

Using the antibiotic with the lowest MIC increases the chance of a quick, clean cure. That means fewer repeat treatments, fewer chronic cases, and less milk loss. 

2. Saves money 

Choosing the right treatment the first time avoids wasted tubes, wasted labour, and wasted days in the sick mob. 

3. Protects antibiotic effectiveness 

Using the most effective antibiotic - and avoiding ones that won’t work - reduces selection pressure and supports responsible antimicrobial use. That’s good for your herd, good for consumers, and good for the industry. 

5. Supports better long‑term herd health decisions 

Over time, MIC patterns help you and your veterinarian spot trends, refine treatment protocols, and strengthen mastitis prevention strategies. 

The Bottom Line 

MIC data turns mastitis treatment from guesswork into precision. For farmers using Mastatest, it can mean faster cures, fewer losses, and smarter antibiotic choices — all backed by real science from your own herd. Find out more about how it works here.