I am milking my does and do not drink much milk and havent had time to figure out how to make cheese. My dogs get milk every few days and so does the farm cats but is it ok for my hens.
I am mixing it in there feed once a week but would like to feed more. They still eat oyster shells like crazy and some have extra calcium spots on the eggs but others are thinner. Will the milk mess up anything? I buy the feed semi-locally its a corn-soy and gmo free that i really like but it has powder in it so i always add a bit of water to it daily. I have 18 birds and feed 3-4 quarts of feed a day plus free ranging 4 days a week.
		
		
	 
I have read of chickens being offered milk free-choice in a dish (source: a book published about a century ago.)
Maybe mix milk into some feed, and water into other feed, and give the chickens a choice? If you do it half each way, you can watch which one they eat first or most, and adjust the amount on later days. If they all choose to eat the feed with milk, it is probably fine to keep doing it, unless you see some kind of problem.
	
		
	
	
		
		
			I am mixing it in there feed once a week but would like to feed more. They still eat oyster shells like crazy and some have extra calcium spots on the eggs but others are thinner. Will the milk mess up anything?
		
		
	 
Milk is a good source of calcium for people, but it has nowhere near the calcium level that a laying hen needs. It is good that your hens still have access to the oyster shell, and they obviously do know to eat it when they need it.
Milk is a pretty good source of protein, although of course that protein is spread out in a large amount of liquid.
When people worry about feeding milk to chickens, they are usually concerned about the lactose.
Scientific studies have found that lactose can cause diarrhea and other problems in chickens, when it goes above a certain level per day.
I believe they could not get the hens to eat that level of lactose if the hens were given any choice about what to eat, but I am having trouble finding the study I remember. Instead, I keep finding ones that show hens can benefit from lactose up to (some percent) of their feed.
I would say, giving the hens an option (feed with milk vs. feed with water) would be a fairly easy safeguard, at least until you learn whether they can eat just the feed with milk and not have problems.
If you do not see any problems, then it is probably fine. If you do see problems (especially diarrhea), reduce the amount of milk (less often, or less at a time, or more options for other feeds.)