both mine moved to cows milk at 1 year. There is no need for formula after 1 year. If you want to give them extra vitamins then give a supplement alongside full fat cows milk or add in extra fruit/veg.
as far as I am aware there is no need to give a baby over a year old formula - they should be getting the additional nutrients they need from food. DD2 (14 months) never had formula (not for want of trying, just wouldn't drink it!), so went from breastmilk to cow's. She likes full fat, creamy milk (Jersey milk form M&S ), and we warm it for her...
We just weaned DS at 19mo by gradually reducing the amount of formula in his last bedtime bottle & making up the difference with cows milk, 6oz f + 1oz cows, 5+2 etc over the course of a couple of weeks until he was sinking a whole bottle of cows milk.
We then moved to a cup and he definitely has a much smaller volume of milk now than from a bottle, maybe 2oz per night on average but I am trying to remain relaxed given his diet is otherwise pretty good.
I can see the benefits in the odd cup of formula as a sort of wet vitamin boost if he's teething or not v hungry but I've given them enough of my cash over the past 20months tbh. I am putting on my sceptical head and making assumptions but would imagine most of the available public information is produced or funded by the formula manufacturers to keep you buying their product. But others may have something more useful here.
is there anything to be aware of / concerned about? / Do you just do it, or should you reduce the formula and introduce the cowsmilk? Is there any reason to leave him on formula rather than make the move to cowsmilk? What are the advantages / disadvantages to either ? If there are links to this information, I'd be grateful to be pointed in the right direction. Thanks!