Here's pics of ingredients an analysis from bag. Is it a good feed to use?
Run, don't walk, away from this.
The top ingredients list grains. Corn (highest NSC at about 70%), barley (second highest NSC at over 50%), and the grains they are not specifying is likely oats (lowest NSC of all grains at about 40-45%). NSC is to horses what fat is to humans. Some is needed, but very little. A horse's digestive systems is designed to normally deal with a bit less than 15% (but I use 15 since it's easy to remember LOL). Just as too much fat ultimately harms humans, too much NSC is the slow and silent killer of horses. Secretariat was put down at 19 as the result of laminitis (the number cause being to much NSC in their diet). He was feed a diet of oats and rich hay (death by NSC....can take a couple decades depending the situation and what the negative effect is, but it will shorten their life in some manner).
Anything with grain is something to avoid.
Use beet pulp (very nutritious, with miniscule NSC and all fiber which is good for their hindgut). Copra, which is very nutritious and super digestible (most, if not all, gets absorbed while in the foregut) and again negligible NSC. Just remember to keep the mineral ratios correct. In the case of beet pulp and copra, beet pulp is very high in Ca, but has virtually no P. While copra is high in P but lower in Ca (which the opposite ratio of what a horse needs....so if you mix them about 50/50 and you'll get the ratio of Ca to P around right). Just avoid anything with grain. Think of it as eating a pound of bacon with every meal and pound of fatback with Sunday dinner. Taste great and it won't kill you right off, but eventually the body will pay a price for it.