Just be aware that soaking can also leach 20% of the protein out too..
Currently struggling with mine.. I was also advised not to add oat straw either in more than 25% straw to hay/haylage ratio as its affecting his protein levels whether soaked or not.. And is on a couple kg of un molassed alfalfa chop with beet and balancer in addition to 12kg haylage in a net per day..
He needs blood tests for urea and creatinine levels now to check on his protein metabolism.. I've spoken to several experienced and/or high profile nutritionists after being given their names from the BHS..