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Chapter 9

Investigating Grades

Handbook

Investigating Grades

Grades cost you money, milk, and reputation. But before you start replacing rubberware or blaming the vat, stop and think: grades aren't random. They're caused by something specific, and that "something" can usually be found and fixed fast... if you know where to look. Have a read here and check in with Max, our grade wizard.

What to Check First

When a grade lands, don't panic. Start smart and work systematically.

1. What kind of grade is it? 

- Coliform?

- Thermoduric?

- Bactoscan?

2. What changed recently? 

- New staff?

- New wash routine? 

- Different chemical supplier and/or new cleaning routine? ***It can affect.

- Skip-a-day collection?

3. When was your last good result?

- Compare milkings.

- Match changes in cleaning or milking practices.

4. What's your gut telling you?

 - Trust experience and then back it up with evidence.

Quick Wins vs Rabbit Holes

There's a difference between solving a problem and just doing stuff. Too many people throw time and money at the wrong target. Here’s how to avoid that:

Quick Wins

Rabbit Holes

Check filter, jetters, seals, and stirrer

Replacing all rubberware "just in case"

Inspect top of milkline & claw bases

Scrubbing the vat for the third time

Review wash water temps & contact time

Guessing chemicals aren't strong enough

Smell for coliforms at liner ends

Paying for outside help before you inspect

When It's Not Hygiene and When It Is

Not every bug in the vat came from a dirty plant.

It's probably hygiene if:

• There's a visible build-up (especially protein)

• Hot water is borderline or inconsistent

• You haven't done a full inspection in weeks

• Grades follow a pattern (e.g. same milking each time)

It's probably not hygiene if:

• The grade appeared suddenly with no changes

• The milkline and vat look spotless

• There's a spike in somatic cell count at the same time (pointing to mastitis)

• The lab identifies environmental bacteria or spores (often linked to silage)

Golden Rule: Start at the End

Most people begin inspections at the cow shed. Wrong.
Start at the vat and work backwards, it’s generally a quicker inspection as 1 in 4 hygiene grades can be traced to the vat. Starting here saves you spending hours looking elsewhere first. 

Summary Checklist: First 10 Things to Check

1. Vat interior (look for protein film)

2. Stirrer and valve seals

3. Filter tube (especially top lip)

4. Liner ends (feel and sniff!)

5. Milkline joints and high points

6. Claw bases and sight glasses

7. Jetters (check for blocked or faulty ones)

8. Receiver (especially upper surfaces)

9. Wash water temperature log (start/dump temps)

10. Last 7 days' cleaning routine (alkali/acid schedule)