When choosing a supplement or fortified feed I generally consider the following (for an "average" 1000 lb horse at maintenance):
The amount fed in one day provides a minimum of - Copper - at least 125 mg
- Zinc - approximately 3 times the copper
- Iron - preferably the supplement or feed has no added iron (check ingredient list) and the total iron is no higher than 4 times the copperÂ
- Vitamin E - this should be supplemented to 2,000 IU total if not on pasture - most supplements and feeds contain much lower values.
Some supplements or fortified feeds can be safely fed at higher levels than the "usual" serving size but first check that this won't provide excessive vitamin A, vitamin D, selenium or iodine. I rarely use anything "formulated for grass" as many grass hays alreadyhave adequate calcium and using a product "formulated for grass" willfurther unbalance the calcium to phosphorus ratio.
If calcium and phosphorus are added, look for a ratio between 1:1 and 2:1.Â
Regional Supplements Regional Supplements include the three Arizona mixes I developed and which are manufactured and sold by HorseTech, as well as Sally Huggs' California Trace.
Omega-3 Includes a calculator plus a pdf "snapshot" so you can see how different feedstuffs affect Omega-3 ratios. This originally began life to calculate how to increase phosphorus levels - thus the "Net Phos..." title.Some new products have been added to the Omega-3 Sources chart.  [I haven't include any fish-based products.]
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