After returning home from a day away, my 12 year old gelding munched down on left-over soaked alfalfa cubes from the morning feed that were still in his food bowl.  I'm in Florida and it was a relatively hot/humid day.  An hour later (dinner time), he would not eat grain, pawed, and would try to lay down.  I Banamined and walked him.  A short time later he resumed eating wet hay and drank water--3 hours later I finally got a poop.  Is it possible the cubes fermented and caused the issues?He drank plenty and ate while away - I don't think this was a dehydration issue.

It's possible but not usually a problem from morning feed to afternoon but if it's really warm maybe . More than likely it was a little gas pocket someplace that just needed to move . With these things you just never know and it's frustrating . 

I would say yes. It doesn't take long for mold to start to grow when something is wet, in a pile/bucket, in the heat and humidity of Florida. I'm in Louisiana so I understand. If you're in the same shape we are, everything is stinky and rotten already because of all the rain and standing water. The flies have been horrendous the past week, also. 

Yes, they will spoil in that time frame here in GA/FL.  They also develop a smell.  It's that time of year.    

Yes 100% can happen when it's hot and humid. I'm in Texas and I won't let things soak outside overnight or during the day in the late spring into summer. It'll be in my house if it needs prolonged soaking. If it's not eaten a within a few hours (which pretty much never happens) I'll toss it out. Between humidity and flies .. gross.. i have some in laws that soak their cubes outside year round and the other day I saw a layer of foam sitting on top the soaking cubes in the barn. It really doesn't take long for things to ferment when it's especially humid. 

What cubes do you feed? is there anything other then alfalfa in them? 

I always clean out any leftovers but I am a freak lol