It is pretty common knowledge that too much starch in a horse’s diet can increase the risk of colic or laminitis, and may contribute to the development of insulin resistance. Many owners also blame sweet feeds or other high starch and sugar feeds for negative behavioural issues.
Researchers in the UK shared work on “The effects of a high-starch or high-fibre diet on equine reactivity and handling behavior” in the journal, Applied Animal Behavior Science (the article is currently in press). The authors, Bulmer, McBride, Williams and Murray sought out to determine how dietary starch content (high starch at 0.7g starch/kg body weight/meal and low starch at 0.3g starch/kg body weight per meal) affected the horses’ behaviour during reactivity tests, in addition to monitoring the horse’s heart rate. The reactivity tests included a novel stimuli test, where time and behaviour to approach a feed bowl in the presence of a novel sound (white noise), and a handling test, where a feed bowl was situated beside a plastic red and white curtain and the horse was allowed an initial approach on its own, followed by with a handler.
The findings showed that reactivity and handling behaviour, as well as heart rate, was elevated in horses fed the higher starch diet.