Nutrient requirements, feed formulation and environmental constraints: a new focus is needed in the equine industry

The main problem I have with the opinions expressed in this article is that they fail to take into account that the mineral and protein content of the feed/grain portion of the diet is minimal compared to the hay. You mention copper, which is a good example of why well formulated feeds have generous copper levels (but rarely as high as 50 unless it is a mare and weanling feed). A horse getting 5 lbs/day (usual moderate to high performance feeding level, will get 96 mg of copper from this source at 40 ppm. Copper levels in forage are very commonly deficient. If the hay has a copper level of 5 ppm, and the horse is getting 15 pounds, this is an additional 34 mg, for a total of 130 mg/day. NRC calls for consumption of between 2 to 2.5 of body weight/day at moderate work loads, which at 10 ppm copper works out to be 90.9 to 113.6. The 130 by comparison is not extreme, and since copper analysis may be off by as much as 30 it is more than justified in my opinion. A similar situation can be seen with complete feeds. The formulation must allow for adequate mineral intake even at the lower recommended feeding ranges. One premier brand for example suggests starting at 6 pounds/day, and has a 35 ppm copper content, for a daily intake of 95.5 mg of copper, actually a bit low. Personally, I do believe there are excesses in many commercial feeds but primarily because they fail to take into consideration the most common excesses in the forage, such as iron and manganese. The major problem with all of them is that while they can help guarantee that individual mineral requirements are met, they cannot possible truly balance each and every hay type with respect to correct mineral ratios. As for protein, I agree there may be many horses getting more crude protein than they actually need, but again not by much. As you pointed out, we simply dont have the research needed to identify exercise needs or, even more importantly, essential amino acid needs. Since there are many horses receiving the same type of hay for years on end, with a set amino acid profile, additional protein sources to provide a diversity of amino acids seems warranted. While many hays contain adequate crude protein, many are also deficient or barely adequate. A horse consuming 5 lbs/day of a 14 protein hay is receiving 318 grams of protein from this source, only about 30 of the suggested daily protein intake for a 1000 lb horse in moderate work. Eleanor M. Kellon, V.M.D. Equine Nutritional Solutions 58 Maple Farm Road Ephrata, PA 17522