Originally Posted by Wallaby
About flax - I just buy the whole seeds in bulk at my local grocery store ($.60/lb) and they get digested just fine. It's MUCH cheaper to do it that way and, ime, nutritional value is absorbed whether they're whole, ground, or oil.
I agree with this. I feed 1/4 cup of whole flax seed to my horse daily, and don't see it coming out whole on the other side
Given how quickly flax seed loses its nutrients when ground (and how much more expensive stabilized ground flax seed is) I'd pick whole over ground.
I think the choice between whole seeds and oil really depends on your end goal, however. The oil provides about 4x as many calories by volume, but doesn't have anything other than (healthy, high omega-3) fat. So, if your goal is to help with weight gain or otherwise increase fat content of the diet, oil is the way to go. If your goal is more to get the good effects of flax for a horse that is already getting enough calories, then flax seed is a better choice.
Of course, depending on the cost of the oil and whole seeds, it still might be more economical to feed whole flax seed, even if you're looking to increase fat content. 1/2 cup of oil at $20/gallon is $0.63. It would take a little over half a pound (~1 2/3 cup) of whole flax to provide the same amount of fat. If the seeds are $0.80/lb in your area (that's how much I pay for mine), that's only ~$0.45.