Yes, I was aware of high phosphorus levels. If you're feeding temporarily for whatever reason, it should be OK, though.
I discovered that the calcium-to-phosphorus ratio is about the same with most cereals or grains, all being much higher in phosphorus. This includes whole oats and whole corn, which have similar ratios (averaging a 1 to 10 ratio), and maybe some of you even feed your horses those grains...there is one exception, though, but first...
There is, as it seems with all things that are not hay, a drawback on beat pulp: next to no vitamins. But, it's true the ratio of calcium/phosphorus is more proportionate. The calcium levels are at 2% and phosphorus is at 5%.
Surprisingly, corn bran may be better to offer your horses if you can find it. Although, it still has no real nutritional value, either, its calcium levels are at 3% and phosphorus is at 5%.
But everyone has a valid reason for avoiding bran. As for me, My daily feeding routine is just orchard grass hay and a mineral salt block. I'll ad something here and there, bran included, when appropriate. And, I still believe, HYDRATION is most important in the winter.
I don't mind if anyone disagrees, though!