The following intakes are for a 500 kg/1100 pound horse at maintenance or intermittent light work, consuming 10 kg/22 lbs of hay.

Nutrient

Total Intake

Concentration Required in

Hay

Calories (average to elevated range under maintenance)

15.2 to 18.2 Mcal

1.52 to 1.82 Mcal/kg

0.69 to 0.87 Mcal/lb

Protein (Note: range is for average to light work)

630 to 699 grams

6.3 to 6.9% crude protein

Lysine

20 to 30 grams

0.2 to 0.3% lysine

Calcium (150% NRC)

30 grams

0.3%

Phosphorus (150% NRC)

21 grams

0.21%

Magnesium (2:1 Ca:Mg, which is over 150% NRC)

15 grams

0.15%

Potassium (NRC)

25 grams

0.25%

Sodium (NRC)

10 grams

0.1%

Chloride (NRC)

40 grams

0.4%

Sulfur (most sulfur in hay is as sulfur containing aminoacids)

15 to 20 grams

0.15% to 0.2%

Iron (NRC)

400 mg to 450 mg

40 to 45 ppm

Copper (150% NRC)

150 mg

15 ppm

Zinc (NRC)

450 mg

45 ppm

Manganese (NRC)

450 mg

45 ppm

Selenium (double NRC)

2 mg

0.2 ppm

 

Also iodine, 3.5 mg, not included on hay analyses, not likely to be adequate unless hays grown in coastal areas.

Notes:

 I double NRC for selenium since few horses maintain serum selenium even in the mid range on NRC intakes.

 Chloride will not be on the hay analysis but is included her to show that even early cuttings are likely to provide most, if not all, the chloride requirement

 Sodium, potassium and chloride should be at base NRC for horses not working much. In working horses, calculate needs by hours worked, not by the NRC tables.