Troubleshoot your milk grade with
Max the Grade Guru
Grades don’t fix themselves but Max helps you sort them before they cost you.
Answer a few straightforward questions and Max will help you explore likely causes of your milk grade and practical next steps. It’s another way we share our know-how, helping you understand your system and make informed decisions. If you need more support, contact the Agmax team.
Grade guide
What each grade means and what to do about it
Start with the type of grade you were given, read what it usually points to, then open the result that sounds like your shed.
Coliform
A coliform grade means milk soil is being missed somewhere in the plant, usually in one spot. Coliforms like warm, dirty places such as test hoses, seals and blocked jetters.
- Manure contamination You've got manure in the milk. That batch is no good, so you'll have to dump it and clean everything the manure touched.
- Wash water too cold Cold water cleans won't kill coliform bacteria. The wash needs to start at 85C and stay above 55C, or fat can re-stick to the surface.
- Cooling too slow Cooling too slow or refrigeration too warm. Warm milk is a coliform breeding ground.
- Soft soil deposit Soft milk film can be hiding in every and any surface, nook and cranny. Look for shine and get scrubbing.
- No obvious source You've ruled out the basics but still have a coliform grade. Odds are you've missed a soft soil patch somewhere, so it's time for a full strip down.
Bactoscan
Bactoscan measures total bacteria, whatever the kind. A high count means bugs are building up somewhere, and it usually comes down to plant hygiene, cooling or mastitis.
- No bactoscan grade You're in the clear. Fonterra and other processors don't treat A+, A or B as grades, so there are no demerits and no action required.
- Hygiene issue in plant or vat This one's on hygiene. You've got bugs somewhere in your system, and 'clean enough' is not clean.
- Cooling failure Slow or weak cooling gives bacteria time to multiply. And multiply they will.
- Mastitis Your bactoscan grade is due to cows with mastitis. Check with your milk company whether it is contagious or environmental mastitis, and talk to your vet.
- Missed something? If your grade is bactoscan hygiene (not mastitis) you have missed an issue with your hygiene or cooling. It's time to dig deeper and start from scratch.
Thermoduric
Thermodurics are tough bacteria that survive hot washes and even pasteurisation. A thermoduric grade usually means your clean is not reaching every spot, or a protein deposit has baked on.
- Protein deposit in the milk line You've got old milk soil (protein deposits) stuck in your milk line. It's a common cause of thermoduric grades.
- Protein deposit in the vat You've got old milk soil (protein deposits) stuck in your vat. The vat is the last stop before the tanker, so 'clean enough' is not good enough.
- Perished rubberware Old rubber cracks, breaks down and gives bacteria a place to hide. If it rubs off with black residue, it's time to replace it.
- Environmental thermoduric You've done the cleaning, ruled out everything else, and your milk company confirms the bugs are coming from the paddock. That makes them environmental.
- Missed something in your clean If your thermoduric is non-environmental you have likely overlooked a small but filthy spot such as the test bucket hose, a stubborn milk filter housing or a vat deposit.
Somatic cell count
Somatic cell count is about cow health rather than plant hygiene. A high count is a herd issue, so check your herd and talk to your vet to find the cause.
- Unknown mastitis source Don't guess, get professional advice. Call your vet and get samples cultured to identify the strain.
- Contagious mastitis These bugs spread like wildfire in the shed. Call your vet immediately.
- Environmental mastitis The bugs are coming from bedding, mud or poor pre-milking hygiene. Call your vet immediately.
- Still unsure? If it's not clearly contagious or environmental, your best move is to test, diagnose and act, and get your vet involved.