I brought home milk from a neighboring cow that had just freshened. It had a pH of 6.4 which is what alerted that something was wrong. I checked on line and that pH is normal for colostrum. Colostrum also has much higher total solids, how much was unknown. Mostly likely, 18% or greater total solids. This meant that I had to guess at how much salt to use, and I wouldn't know by yield if I had met my target moisture. Surfing the net I found an article on feeding calves that gave a method for determining total solids in waste milk so you could ensure they were enough nourishment. The article said to take a measurement on the brix scale and add 2%. They were using a refractometer as it is more convenient that a hydrometer. I decided to verify this for myself.
I bought some whole cow milk and warmed it to 60 degrees, which is the temp my hydrometer is calibrated for. It read 9 on the brix scale. Add a 2% adjustment and you get 11% Total solids. So likely this will give you an idea of total solids in your milk so you can estimate your yield. Of course some of the solids are lost in the whey, but I suppose you would just get a brix reading on the whey... I think this should be helpful to know so you can better estimate the salt needed and whether or not you've hit your moisture target, when working with a milk of an unknown composition.
