For the sake of your horses' health, PLEASE find a way to feed a decent amount of decent quality hay daily! As others, even those who routinely feed hay pellets as a major part of their horses'daily feed regimen, have said, horses have evolved and are designed to take in small amounts of forage that requires thorough chewing, and thus SHOULD HAVE hay in some reasonable form daily. I am an STRONG believer that it is vital to horses' health that they get to eat long-stem fiber in sufficient quantities. It is not ONLY about nutrition; it is also about the 'experience' of grazing,or the simulation of grazing that comes by feeding HAY, which at LEAST requires the horse to chew, chew, chew! Not getting that time-consuming and evolution-dictated experience can and so often does lead to other health issues for the horse; that is a huge part of the serious drawbacks of not feeding SOME form of quality hay! Ulcers from stress, destructive habits, whether self or surroundings-destructive, like wood chewing,cribbing, and the like, are MUCH more likely to develop in horses that finish their feed in 10 minutes(as HG so correctly noted!)...when they are in a dry lot, they are almost certain to try to find something to satisfy that 'foraging need' after that...often something detrimental to them or their surroundings!
Yes, it may help to soak hay pellets; it is most likely safer for the horse, and probably slows down the consumption rate. Another option might be to feed some well-soaked and WET beet pulp every day; you can research the maximum percentage of their total feed intake that would be safe to feed, as beet pulp should not be TOO HIGH a percentage of their daily fare...and I would personally recommend beet pulp PELLETS instead of shreds; pellets make take longer to soak, but the 'bits' they break down into are smaller and less likely to theyselves lead to a choke or impaction. That said, I strongly advocate that horses STILL should get a decent amount of hay every day! Several very good suggestions have been made (I like the slow-feeders--they are a great idea and really help slow down the hay consumption RATE when used correctly); surely you can choose from among those, and come up with a way to provide your mares with a way of feeding that will satisfy their genuine nutritional needs in every way possible.
I want to add...I have a 28 YO mare who now gets only a 'complete' senior feed(TC Senior, which *could be* the only thing she eats, according to the mfg.),1/4" alfalfa pellets, and once daily, good WET soaked beet pulp pellets. She has had regular tooth maintenance for many years. She is at high risk for choke from trying to eat hay in any quantity sufficient to maintain her; hence the pellets. She will not TOUCH soaked hay pellets, or even, soaked hay, so that's not an option. For now, she is maintaining good condition, and at her age, she doesn't 'stress' as much as a younger/more 'sensitive' horse might over the fact that she is finished with HER 'hay' long before everyone else(she is fed separately, as are all but two of mine), but she can SEE them still eating! I try to help her all I can by feeding three times daily, giving her a small handful of alfalfa LEAVES a couple of times daily, splitting her hay pellets AND her Senior between two feeders, and sometimes giving her half, then the other half a while later,and putting large rounded rocks in her(ground-level, w/ mats underneath)feeder to'slow down' her consumption rate.I feed her pellets as her major 'forage' source ONLY because it is my ONLY choice for her; I would NOT do so for any of my other horses.
Margo
