Hi Mike,
OK, you know I had to grab the nutrition question. According to NRC,
the digestible energy required per day by a working horse is expressed
by the formula:
Mcal/day = 5.97 + 0.021W + 5.03X - (0.48X squared), where W equals the
horse's body weight in kilograms, X = Z x kilometers x (10 to the
negative third power) and Z = the weight of horse, rider and tack in
kilograms.
Even this is really an estimate, since terrain, weather, skill of the
rider, the individual horse, etc. can all have an effect.
However, for those that just want an answer, not a #$%&*! lecture in
mathematics (except for Truman, who's probably eating this up), the
general guidelines for a 400 kg (880 pound horse) are:
Maintenance: 13.4 Mcal
Light work: 16.8 Mcal
Moderate work 20.1 Mcal
Intense work 26.8 Mcal
Hope this helps.
Susan Evans