When you milk the cow it will be a different color. I wish I had a picture to show you the difference between colostrum and the milk we consume. The colostrum won't really hurt us but it's more for the calf's immune system. The milk we consume is more of a white since they pasteurize it and remove the cream out of it compared to raw Jersey milk (TO DIE FOR!!!). Raw milk has a hint of yellow to it do to the cream but for the most part it's white while colostrum for the most part is yellow. I believe a cow only has it for the first day or so when the calf begins to nurse. I'm pretty sure but I could be missing a detail. With our Jersey cow we would leave some milk for her calf but we would milk a lot of colostrum on the first day and froze it incase we would have a calf that needed colostrum. Jersey can produce 3 to 4 gallons a day and a calf would probably only drink half of that or less that's why you need to milk a dairy cow or have another calf on them to prevent the cow getting a soar udder or can cause mastitis.
Oh wow, that's really interesting! Thanks for all the info. and wait i thought raw milk was dangerous.