One of the things they say, jaykay, to avoid problems in tups and wethers eating the ewes' ration, is to make sure there's always plenty of water available. Not a problem at your place!
Especially if you have a salt lick too, so he can lick on at that and get a good thirst up, then drink plenty of water to flush everything through.
I just went searching for the good info that has been posted on this subject before. Heygates have a really good info page
here.
From the Heygates sheet, one of the key things is that the cake should have a calcium:phosphorous ratio of at least 2:1 and should have no added magnesium. If the ingredients list includes Ammonium Chloride, it's probably fine for tups and wethers.
It's worth reiterating that this problem is actually even more likely to occur in castrated males than in entire ones.
I'm sure I remember someone talking about something simple that could be added to the tup's ration to make sure he had no problems, and I couldn't find that one. Anyone remember?