It’s a discussion that keeps resurfacing. Should you feed hay before grain, or vice versa. Should you even worry about it? What happens?
Some say you should feed grain first because the horse knows it’s coming, won’t eat the hay anyway and will be agitated and stressed waiting for the grain to show up.
The other camp says feeding hay after grain will push the grain through the stomach and small intestine too fast, producing a big insulin spike and overloading the hind gut with starch while hay before grain will reduce stomach acid because of more saliva and will hold the grain in the stomach longer.
What is the real evidence to support either of these?
The glucose and insulin response is a measure of how much starch (and sugar) is being presented to the small intestine. A 1999 KER study found if you feed oats only there is a higher glucose and insulin response if you wait 4 hours to feed any hay. The glucose and insulin responses were lower when hay was fed with grain or within 2 hours of grain.
A study by Dr. Vervuert et al in 2008 looked at insulin and glucose responses to feeding a diet of oats and alfalfa. They found no difference in levels when oats were fed first versus feeding alfalfa first but did note lower levels if they were fed together.
With a desire to really get to the bottom of these issues, Jessica Saul explored the problem in a thesis for Ohio State. She used a diet of 0.5% of bodweight as a pelleted concentrate and 2% of bodyweight in hay. She found no difference in glucose and insulin responses with pellets fed first or hay fed first. Fecal pH was also measured as an indicator of potential starch overload in the hind gut but this did not change with feeding order either.
The bottom line here seems to be that at least in terms of insulin meal responses and changes in the acidity of the hind gut it doesn’t make any difference whether you feed hay or grain first, at least if the hay is coming within 2 hours of feeding grain.
Eleanor Kellon, VMD