Some owners might be searching for the most cost-effective ways in which to feed their horses, especially as provision prices continue to rise. Recently, a team of German researchers took a different approach to evaluating the effectiveness of horse feeds by carrying out a study establishing which diet–hay and grain or solely forage–consisted of a more "physically effective fiber."

"Physically effective fiber is a term from cattle nutrition that describes the potential of a fiber to produce saliva and buffer a meal," explained Ingrid Vervuert, PD, DVM, professor of veterinary medicine at the University of Leipzig, Germany. "In equine nutrition there are some efforts to introduce this term."

To that end, using electromyography (EMG), Vervuert and colleagues measured equine masseter (jaw) muscle activity when the animals consumed a roughag-only diet (Diet A) versus a roughage and concentrate diet (Diet B).

In Diet A, four horses consumed fed free-choice meadow hay, meadow haylage, and straw alfalfa chaff (SAC), in that order, twice daily for 21 days. In Diet B, four different horses consumed 0.26% bodyweight (BW) cracked maize (CM) in addition to three different meadow hay allocations in a random order:

  • No hay for 12 hours, then 1.2 kilograms (kg) of hay per 100 kg BW, divided in two equal portions;
  • 0.6 kg hay/100 kg BW hay fed before CM, and the same amount of hay fed 10 hours later; and
  • Free-choice meadow hay fed for 12 hours before CM, with additional free-choice hay after CM.

For both diets, researchers measured feed intake time, chewing frequency, and masseter muscle activity.

Key findings included:

  • Hay/ haylage had the greatest feed intake time, followed by SAC, then CM;
  • Restricted hay fed prior to CM did not affect intake time of CM;
  • CM intake significantly increased when horses were fed free-choice hay before CM; and
  • Chewing force and duration of chewing cycle were lowest for CM and highest for hay/ haylage.

The team concluded that roughages were associated with "intensive masseter muscle activity," likely to stimulate salivary production and flow rate. This is key to helping maintain a health digestive tract, as saliva plays several important roles in food digestion including easing chewing and swallowing; starting the digestive process via enzymes, and acting as a buffering solution to help maintain proper gut pH.

Thus, to provide horses with the most physically effective fiber, ensure the majority of their diet is composed of forage, Vervuert also suggested limiting concentrate intake to a maximum of 1 kg per 100 kg BW, when possible.

The study, "Electromyographic evaluation of masseter muscle activity in horses fed (i) different types of roughages and (ii) maize after different hay allocations," appeared in the Journal of Animal Physiology and Animal Nutrition in March 2012. The abstract is available online.