Feed advice please - protein and magnesium

[M&M&G]

On advice of the vet, my cob needs to lose weight and I need to do this over the winter to stand a chance next spring. Amongst other things (increased work, decreased rugs)I have started to soak her hay and she get a small scoop of chaff to carry her supplements. I feed Equiminns Advanced complete and a tablespoon of salt. She is out during the day (limited grazing).

I have read on a number of threads that it is advisable to feed additional magnesium if feeding Equiminns supplement - having looked, the choice is overwhelming, is there a particular type/compound of magnesium as that seems to vary?

I am also finding that she seems to be very hungry - more than normal! I am assuming it is down to soaking the hay taking out the nutrients as I am not feeding less. I have also read that soaking the hay takes out protein too which can cause them to be ravenous. Again, looking for advice on good proteins for a horse eating soaked forage, or whether it is a good idea.

Would really appreciate advice from those with more knowledge as I am finding the more I try and read up, the less I understand and I'm getting confused!

 

[P.forpony]

Quick questions,
how big is your cob? ie condition score
What’s her current workload?
Is she clipped?

 

[Littlewills]

I feed mag ox. People will say some are better than others, but mag ox works just fine for me. Protein wise I feed pink mash and high protein grass nuts, If you dont want to add to the feed there are supplements you can get, tri aminos and whey protein are the 2 I see people using