72 A survey of North American horse diets: What are we missing?

Abstract

Balanced nutrition is critical for the health and well-being of horses. To date, there is limited information on the composition of North American equine diets. Here, we describe an analysis of 200 equine diets and how they compare with NRC requirements. Owners from the US and Canada submitted their diets for review by a nutritionist. They were asked to provide information on their horses’ age, weight, exercise level, diet composition, and health concerns. They were also asked to classify their horses' body condition as underweight (UW), slightly underweight (SU), normal weight (NW), slightly overweight (SO), overweight (OW), or obese (OB). Our sample population includes mature horses of various breeds and exercise levels. Diet nutrient composition was based on guaranteed analyses provided by manufacturers and an average hay analysis corrected for variations in regional soil mineral contents, or the hay analysis submitted by the horse owner where available. Nutrient intakes were compared with each horse's requirements based on their exercise level and body weight, obtained from the NRC, to calculate nutrient intake as a percentage of requirements. Wilcoxon Signed Rank Tests and descriptive statistics were used to analyze the data in Prism. Data are presented asmean intakes as a percentage of requirements ± SEM. Our results revealed that diets were providing an adequate amount of selenium (113 ± 8%) and vitamin E (106 ± 7%). Diets were slightly over-supplying energy (118 ± 1%; P < 0.0001), zinc (125 ± 5%; P = 0.0002), copper (151 ± 6%; P < 0.0001), manganese (132 ± 5%; P < 0.0001), and vitamin A (138 ± 8%; P = 0.001). Protein (191 ± 3%), lysine (203 ± 4%), iron (352 ± 6%), phosphorus (192 ± 4%), calcium (292 ± 7%), magnesium (264 ± 4%), and potassium (680 ± 9%) were appreciably over-supplied (P < 0.0001), and sodium was under-supplied (65 ± 5%; P < 0.0001). Interestingly, all horses except those classified as obese were over-consuming energy (P < 0.004), with average intakes for UW horses being the highest (145 ± 8%), followed by SU (127 ± 5%), OW (122 ± 4%), SO (118 ± 3%), and NW horses (116 ± 2%). Understanding the degree to which horses are meeting or exceeding their nutritional requirements is fundamental for formulating recommendations to support performance, longevity, and overall health. This may inform future avenues of research and outreach to improve the health and well-being of the North American equine population.