Ridgetop
Herd Master
Like Mini Horses says: Absolutely 1#:1# ratio milk to grain. You need to weigh the milk, not measure it by liquid volume, then feed a good dairy grain mix in the correct ratio per doe. If you feed the grsin to all the does at once, some will get pushed aside and you won't be able to ensure that each one gets her correct measure. Only feed grain to the milkers on the stanchion during milking. That way you can regulate how much each one gets. Cattle grain will work fine for dairy goats. Until you know how much your goats are giving you might want to pull the kids and bottle feed. Remember that milk volumes will change during lactation unless you are milking twice a day since the doe will adjust her milk production to what is being taken by kids. If you milk twice a day, she will continue to produce at a fairly even level for 8-9 months depending on her breeding. As the kids begin eating more browse, hay, etc. the lactation yield will drop off. Free feed good quality hay in addition to any grazing or browsing they are doing.My girls get more feed, give more milk but, full sized goats and heavy producers. I'd say close to 1# feed for 1# milk....plus hay, heavy on alfalfa.
An 18 month old buckling is still growing. Definitely increase his hay and you can give him some of the cattle grain too, but since he is not rutting now, be careful not to feed an excess of grain. During rut some bucks will drop weight since they will be more interested in breeding than in eating. But they can pick up body condition when the does are settled and no longer cycling. Removing the does once they are bred will give him full access to all the feed in his pen.