Mike CT, you've provided the "micro-micro" milk operations details! 
Dare I ask how you came to know all of that? The small family farm was enough, with Father working for the Pittsburg and Shawmut Railroad, as a machinist, to put (5) of us through college. Fair amount of work, but a life long education. IMO. There were no college loans or debt, when we graduated. Four of us graduated from Clarion State (PA) college/university. Brother Robert, who works for USDA in Vermont, graduated from Penn State. Brother Dan attended a trade school and has been a machinist all his life.
When I lived on a farm, the farm mom would hand-milk Beulah first thing in the morning, pour the milk from the pail through a paper filter to remove bits of the cow's behind (if you catch my drift), then pop the milk in to the institutional-sized milk dispenser in the kitchen for us all to drink. Milking was done with stainless can type milkers (vacuum equipment), eventually after I graduated from college/one less farm hand, a pipe line milker was purchased. Brother Richard left the farm, an endless chain gutter cleaner was purchased.
No bacteria testing, no temperature monitoring, no weighing, and I've lived to tell the tale! As a boy scout, I did the Dairy merit badge, which was a pretty good education for a young man. Since I milked the cows, I was also responsible for cleaning the equipment. High bacteria counts, where quickly brought to my attention, and I was scrubbing/cleaning a bit harder.
We couldn't drink it fast enough, so farm mom decided to make cheese -- in the house. Yuck! curds and wheys stink. But that's an operations story for another time. Eventually the local creamery did not do Sunday milk. We were required to Separate the Saturday milk/Sunday delivery, Cream and Skim milk. The Cream was then shipped along with the Monday shipment. The tremendous amount of skim milk was used to feed the calves and us. Mother baked constantly, and used a lot of the skim milk to make puddings. Nothing ever got wasted.
Great morning discussion. Thanks to all who contributed.
Mike CT 
