Measuring the Physiologic Response to Nutrition

Whether for weight gain or loss, speed or shine, nearly everything we offer our horses is given to bring about a desired effect. Stacie Appleton, PhD, and Mike Jerina, BS, presented a demonstration on "Measuring the Physiologic Response to Nutrition" to show how the lab goes about measuring the effect of their feeds, at the Purina Equine Veterinary Conference in St. Louis, Mo., Oct 17-19, 2008.

Every horse at the Purina Mills Equine Research Facility is involved in one of three categories of research: palatability studies, growth and development studies, or exercise physiology.

Current growth and development research at Purina monitors 12 foals to measure skeletal growth, spontaneous activity levels, and body condition scores. Most of the foals are Quarter Horses from similar working cow horse genetic lines. Each foal receives full radiographic studies within three days of birth, with radiographs repeated every six weeks for two years. Scientists place GPS units on each foal to monitor when they move around, are most active, and when they rest. This is used to evaluate how diet affects behavior and activity level. Rump fat thickness is measured with ultrasound to determine a body condition score. Other parameters include weight, skeletal development, insulin and glucose sensitivity, and various blood parameters.

For mature horses, Jerina described an exercise physiology study on unfit, obese horses (body condition score of 8) and response to a weight loss dietary formulation. Each of three groups had eight horses: one group of controls, another was on a diet, and the third group on a diet with exercise.

First, the exercised group was accustomed to a treadmill and associated equipment for two months. Then, they performed a stress test on the treadmill, and were exercised three times weekly for four months. Finally, the stress test was repeated on the treadmill to evaluate how much performance gain was achieved.

The treadmill room at the lab is 70�F year-round to negate effects of climate and weather. Once the researchers are satisfied with the analysis and before a product is brought to market, feeding trials are done at universities, farms, and ranches across the country to ensure the product works in different climates and with different breeds.

This information facilitates fine-tuning, while also yielding insight on whether horse owners will comply with feeding instructions for each product.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her recent book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care (available at or by calling 800/582-5604). She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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