Hi Maggie - thanks so much for your very detailed reply!  This is so helpful.  I am very glad to hear that this hay looks good.  I will move forward with ordering this for my own horses.  As soon as my batch of hay arrives, I am planning to have it analyzed again (just to make sure it really is the same stuff!) and then I will reach out to one of the mineral balancing experts to work on customizing Finnur's minerals.  I had started using the Barn Bag in the spring since, at the time, I just naively knew I had to give him SOME minerals, but didn't know anything about how much/what kind.  Thanks so much for pointing out the high fat level - that's definitely not what I want!  I am stopping the use of the Barn Bag and will replace it with a customized mineral mix based on his new hay. 

Also, thanks for taking a look at my case history to give some personalized feedback!  Over the past few weeks since I discovered this group, I have been working on making some of the changes that you suggested (one baby step at a time - haha).  Finnur was getting free choice hay in slow feed nets for several years - I had bought into the idea that he should never go without hay to avoid cortisol spikes and help him self-regulate.  Well, as you can tell by his physique, he never learned to self-regulate :)  Last weekend, I built a new fence in the dry lot so I am now able to keep Finnur separated from his barn mate and feed him only his designated amount of hay each day.  Three days ago, I ended his free choice feeding and switched to weighing out his daily hay allotment.  I am basing it off an "ideal weight" of 800 lbs, so have started feeding 16 lbs of hay per day.  Does that seem appropriate for an Icelandic horse?  I am still using the slow feed hay nets to try to spread out the time he is eating, but think I may need to go to a smaller hole size now since he's going through it pretty quickly (he has a 1.5" net and can pull hay through quite easily with his nimble little lips!)  Actually seeing what a "correct" amount of hay looks like over the past few days makes me realize how much he was truly overeating before.  No wonder I haven't had any success with his weight loss!

Finally, I so appreciate the advice on managing his sweet itch!  Our bug season is winding down and he is doing a bit better now that I have him on a monthly dose of Ivermectin and regular topical applications of Equiderma (I'm not sure if his improvement is actually due to the Equiderma or just environmental conditions, but I am continuing to use it for now).  I am very hopeful that after a winter of correct hay/minerals, he won't struggle as much with it next year, but it is wonderful to have another product recommendation if I need it for the future.  I hadn't heard of Calm Coat and will definitely give it a try if we continue struggling with sweet itch. 

Once again, thank you so much for your time and advice!
--
-Jenna
August 2018, Cedar Rapids, Iowa
Finnur's Case History: https://ecir.groups.io/g/CaseHistory/files/Jenna%20and%20Finnur
Finnur's Photo Album: https://ecir.groups.io/g/CaseHistory/album?id=68833