Science VS tradition:concentrates and forages

Lucky you guys getting two of these in two posts back to back.

First of all stemming off my last post about the one week boarding issue and grain. I've had quite the few questions asked.
First of all people wondered why it is such a big deal that Indigo missed a couple meals, it's not like the BO forgot to feed her hay right?

Well see horses are relatively simple, yet extremely complicated animals. Wile they are strictly vegetarians, eating forage as the basis of their diet. When forage is available, and I am not talking a couple times a day I am talking ALL THE TIME, horses have relatively little trouble with digestive issues. However in todays horse world there is normally less land than grass can be suitably sustained upon by a herd of horses. If there is grass in a pasture it is often low quality. Just because it's green and "weed free" does not mean it is nutritionally adequate, especially if it is grazed on for a few years and never re-seeded and you don't know the nutritional content of it. Forage should make up 50% or more of the horses diet, preferably 100% but that is not always available or practical. This should be about 1.5% to 3% of their bodyweight each day.

This is where grain comes into the picture.
I want to drill this into your head again GET A HAY ANALYSIS! Every year, every new cut of hay. The soil can change each year, the hay changes. Hay analysis is especially important for horses that fit into the following: Insulin resistant (or may possibly become), cushings, old, young, laminitic/foundered or nurtitionally compromised (cancer, starvation, other diseases). If your horse does not fit into one of those it does not mean you don't need a hay analysis.
Without a hay analysis grain is useless, useless, useless! You may be feeding less or even more than what you need which can harm a horses system in the long run, create toxicities and cause nutritional diseases.
Of course when looking at anything (other than treats of course) you are feeding a horse you should always feed by WEIGHT not VOLUME. After all you weigh your horse, not volumize him. If you have a few normal 50 pound square bales of hay the flakes are not going to be the same size through every bale, and thus do not weigh the same. Find what your horse weighs and adjust according to it's weight and the nutritional content of your hay.
The hay is bad you say? Why not feed more of it to make up?
No, no, no, no, no. Don't ever do this. See a bad quality hay is going to have to sit in a horses digestive system longer to get the nutrients out of it. A lot of the time this is what gives a horse the "hay belly" look. So it's always a good idea to feed a little of good hay that will have quality nutrients in it than a lot of bad hay.

Ok so we talked a little on hay on to grain.
You know the nutritional analysis of your hay, you know what your horse weighs and needs in his daily diet for his workload because not all energy contained in a feed is accessible to a horse. A lot of this energy is lost in the digestion process, so we determine the amount of usable energy in hay/grain a horse consumes in DE or digestible energy. Think about what category your horse fits into to determine his maintenance needs (AKA staying a good weight without gain/loss):

Maintenance (AKA your average pasture puff maybe ridden once in a blue moon)
Light work (two or three or less times a week for an hour or less usually just walk or trot)
Moderate work (4 or more times a week an hour or more spending a larger amount of time in trot and canter)
Heavy work (6 or 7 days a week, rigorous workout, usually 1 1/2 hours or more pulling hard, running hard etc)

Of course these are just guidelines you should be able to fit your horse into one of the above.

I feed grain to make up for the nutrients, carbohydrates and my hay does not have. For instance vitamin E, for every 30 days hay is cut you can cut the vitamin E in the hay in half. After a few months you can imagine theres very little in the hay.
I feed my horses Buckeye grow n win alfa. We have alfalfa hay. It's whats grown on the farm, available to us and we adjust accordingly. Grow N win is a ration balancer. It balances what our hay does not have. Buckeye happened to score above most feed mills when we did comparisons in universityWe also mix it with oats. Our horses are on moderate to heavy work depending on the time of year. We need to balance out what they get in order to keep their weight and energy level.

Other ruminants such as cows are fare more efficient at digesting forages and concentrates than horses. When I mentioned I was upset about my horse not being fed her grain when at the boarding barn for a week it was for good reason.
A change of more than 10% of the horses diet at once can cause micro flora and other good bacteria to suddenly die as the PH becomes more alkaline in the hind gut. See horses ferment their feed in the hind gut unlike dogs, rabbits, cats and even humans where the digestion happens primarily in the stomach. With a sudden change come sudden consequences. The lining on the hindgut may become inflamed and painful, disrupting blood flow. This is what causes problems. Horses are creatures of habit. Not because they enjoy eating at the same time of day, but because their bodies dictate how they live. Horses eating naturally 16+ hours a day, walking around and not in a stall because movement is very much a crucial part of digestion, will rarely have these problems.

Also a question asked on supplements. Right now Indigo is the only one on a supplement. She occasionally when it's bad gets a cough supplement due to her allergic pharyngitis (Kind of like COPD just for dust and mold) she also gets all her hay soaked.

I can see this is probably going to be more than one part as I haven't even skimmed the surface. Any other feeding questions I will try and bring to the light. I did equine nutrition but I am not a nutritionist so I suggest finding a nutritionist that will work with your hay (because you will have got a HAY ANALYSIS!!!! Yes I will be burning that into your brains evermore) and your horses individual needs.