Every cow is metered at the parlour and every collection is metered on the tanker. The two disagree by about ninety litres a day, in the tanker's favour, and the tanker is the one that gets paid.
I milk a hundred and forty cows twice a day and I have done for twenty six years.
There are two measurements and this whole thing lives in the gap between them.
The parlour meters. Every cow goes through the same unit twice a day and the unit measures what she gives, to the tenth of a litre, and it writes it against her ear tag number. That is not for the milk cheque, it is for management: you cull on it, you breed on it, you spot mastitis on it a day before you can see it.
The tanker meter. The creamery's lorry comes every other day, the driver dips or meters the bulk tank, takes a sample and pumps it out, and the docket he leaves is what I am paid on.
Over a year those should agree within about one per cent, which is what you lose to the plate cooler, the wash and the odd spillage. Always slightly in the parlour's favour, because milk gets lost between the cow and the tank and never the other way.
Mine is ninety litres a day the wrong way.
The tank gives up ninety litres more than the hundred and forty cows put in.
At the current price that is about thirty six pounds a day, which is thirteen thousand a year, and it has been going on since at least 2016 when I put the current parlour in and started getting proper cow level data.
Everything I have done, and the parlour company has done most of it.
The parlour meters calibrated. They are ICAR approved units and they get calibrated annually because the milk recording scheme requires it. Every unit, every year, ten years of certificates.
Then, because a systematic error across sixteen units would do exactly this, I had every one bucket tested. That is where you milk a cow into a weighed bucket and compare. Two days of work with two men.
They are right. Within a per cent, all sixteen.
The tank calibrated. The bulk tank has a calibration chart and it was recalibrated in 2019 by the manufacturer, and the creamery's tanker meters are legal for trade and sealed and calibrated by them.
Somebody adding milk. This is a real thing in this industry, in the other direction: people water milk down. Nobody adds milk to somebody else's tank.
And the creamery would know. Every collection is sampled and tested for butterfat, protein, cell count and bacteria, and a tank with somebody else's milk in it shows up as a change in the profile.
My profile is dead steady. It has been the same herd's milk, by every test the creamery does, for ten years.
The cows.
A hundred and forty milkers giving an average of twenty eight litres.
Ninety litres extra a day is three and a bit cows' worth.
I have counted them. Not once: I count them every day of my life, twice, because you count cows in and out of a parlour and if the number is wrong you go and look for one.
A hundred and forty. My herd register says a hundred and forty and the ministry's database says a hundred and forty, and the last inspection was in 2023 and they counted them too.
The parlour at night.
The tank is in the dairy off the end of the parlour and it is emptied every other day.
I have sat with it. Twice, all night, in a chair by the door with a flask, because there is a level probe in that tank and I wanted to see the level move.
Both times, nothing. The level was where it was at the end of the evening milking and it was in the same place at half four when I got up to start again.
So it does not come in at night. It comes in during a milking, and during a milking there are three of us in that parlour and a hundred and forty cows and you cannot hear yourself think.
The one time I got a number on it.
In 2022 I put a datalogger on the tank's level probe, recording every thirty seconds, for a fortnight.
Milking is about two and a half hours. On the trace you can see the level climb in steps as each batch's milk comes through the plate cooler.
There is one extra step in every evening milking.
It is between forty and fifty litres, it takes about ninety seconds, and it happens about two thirds of the way through, and it is exactly the same shape as the sixteen real ones either side of it.
Ninety seconds is how long a batch of sixteen cows takes to let down and be taken off.
What that means, and I have had three years to find another meaning.
Somewhere in the middle of the evening milking, sixteen units' worth of milk goes into my tank, cooled, through the plate cooler, from the parlour, and none of the sixteen meters in that parlour records it.
In the morning milking it does not happen. Only the evening.
What I do about it.
I get paid on the tanker docket, which is the industry standard and which every dairy farmer in this country is paid on, and I declare that income in full and my accounts are done by a firm in town.
Thirteen thousand pounds a year has kept this farm going through two bad years and I am not going to pretend I have agonised about it as much as I should have.
The one change I made was in 2021 and it is the only superstitious thing I have ever done in twenty six years.
The evening milking used to end with me washing down on my own after the lads had gone. Now the last man out is me and one of them, whoever it is, and we do it together and we go out together and I lock the parlour door.
I told them it was a health and safety thing about working alone with machinery, which is true, and which is also on a poster on the wall that has been there since 2009 and that nobody read until I pointed at it.