A Year on a Dairy Farm

5. Chapter 05 The Morning

A double-six herringbone parlor has six places on each side, stepped up from the floor, with the cows facing in toward each other at a forty-five-degree angle. The pit is a trench down the middle, three feet below the cow platform, where the milker stands. From the pit you can see twelve cows at a time — six on your left, six on your right — and the row of twelve udders hanging at chest height. The light is on. The vacuum pump is humming. The first six cows are on the left side and the next six are coming in from the holding pen on the right.

It is four-fifty in the morning.

The first cow up on the left side this morning is a Holstein-Jersey cross with a white face and a small dark patch over her left eye. Her name is Mabel. The older Mabel — there is a younger one now too, in a hutch behind the heifer barn, and Tom keeps meaning to remember to give one of them a different name and keeps not doing it. The older Mabel is eight, and she has been in the milking string for six years, and she walks into her stanchion and lowers her head into the headlock without prompting and starts on her grain.

Tom approaches her from the right side. He is wearing rubber boots, rubber waterproof bib overalls, a long-sleeved shirt under a fleece, latex gloves. The first thing he does is take a small stainless-steel cup with a black plastic top — a strip cup — and squeeze a few squirts of milk from each of Mabel’s four teats into it, one teat at a time. He holds the cup up to the light. The black surface is there to make any abnormality visible: a clot, a streak of blood, a flake of pus. He is checking for mastitis. He is checking for it on every cow at every milking, every day, for his entire adult life. Mabel’s milk this morning is clean.

He sets the cup down. He picks up a foaming applicator of pre-dip — iodine, a deep purple — and dips each of the four teats in it, in turn. Then he turns to the next cow.

The pre-dip needs thirty seconds. While it is working, Tom moves down the line. Cow two: strip, dip, move. Cow three: strip, dip, move. Cow four: same. By the time he is at cow six the iodine on cow one has done its work, and he comes back. He pulls a clean white towel from a stack and wipes the iodine off all four of Mabel’s teats in long firm strokes — one towel per cow, never reused, never shared, into a hamper at the end of milking. The wiping is also stimulation: it tells the cow’s body that something is about to happen.

Then he runs his hand briefly over Mabel’s udder. The udder is warm and full and a little firm; this is what it should feel like. He gives it a light press with the heel of his hand. Inside the cow’s body, the press, the wipe, the iodine, the routine itself, the smell of the parlor, the sound of the pump — all of these tell her brain to release a hormone called oxytocin, which travels in her bloodstream from her brain to her udder and tells the cells of her udder to push milk down into the teat cisterns. This is called milk letdown. It happens within sixty seconds of stimulation. Without it, the milking unit cannot do its job. With it, the milk flows.

Tom takes the cluster — four short flexible cups joined by a manifold — lifts it up under Mabel’s belly, and one at a time places each cup over a teat. There is a small twist of the wrist for each. The vacuum grabs each cup onto each teat with a soft pressing pull. Cow one is now on the machine.

He is at cow two before the unit on cow one has begun pulsing.

What is the machine, exactly?

A milking machine imitates a calf. This is worth saying clearly: every part of the machine has its origin in something a nursing calf does to its mother, and the engineers who designed the first machines in the late nineteenth century studied calves nursing in order to figure out how to do it.

A calf does not just suck. A calf works the teat between its tongue and the roof of its mouth, in a wave that moves down the length of the teat from base to tip, drawing milk out by squeezing it down rather than just pulling on it. The squeeze is the key. A pure vacuum, applied to a teat without rhythm, would not move milk efficiently and would damage the tissue. The squeeze releases pressure on the teat between pulls, and lets blood flow back through the small veins of the teat skin. Without the release, the teat would bruise.

A milking machine does this with two systems. The first is a continuous vacuum, set at about twelve inches of mercury, which is what you would feel as a steady pull on your finger if you put it in one of the inflations. The second is a pulsator, which is a small valve that switches the air pressure between the inflation liner — the rubber sleeve that touches the teat — and the surrounding shell, sixty times a minute. When the pulsator opens to vacuum, the liner collapses around the teat and squeezes it. When the pulsator opens to atmospheric pressure, the liner relaxes and the vacuum on the teat draws milk down. Squeeze. Release. Squeeze. Release. Sixty times a minute. The milk flows through tubing to a receiving jar and from there, through a glass pipeline, into the bulk tank in the next room.

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