DIET ANALYSIS AND THE NATIONAL RESEARCH COUNCIL (NRC)
National Research Council Ponders Nutrients Requirements for Horses Update…………Scientists are working to decide whether to update the National Research Council’s Nutrients Requirements for Horses and, if they go ahead with a revision, you might be able to help…… https://thehorse.com/162976/national-research-council-ponders-nutrients-requirements-for-horses-update/
The sixth revision of the National Research Council (NRC) Nutrient Requirements of Horses is now over 10 years old and it continues to provide the basics for ensuring that nutrient requirements of most categories of horses are generally met and not exceeded to the point of toxicity or reduced to the point of deficiency.
As the most widely used reference standard for horses, NRC guidelines enable calculation of feed requirements according to weight and activity level. They are based on the minimum amounts of nutrients needed to prevent illness, lesions or growth retardation in 50% of horses. What this means from a practical point of view is that minimum requirements aim to avoid deficiencies in 50% of horses. Failure to recognise and account for the other 50% of horses, and those requiring precise and fine-tuned nutrition can lead to improper use of the NRC minimum requirements.
In addition, optimal health, tissue, cell and organ function – not to mention performance and growth – are affected long before clinical signs of deficiency appear. NRC has few recommendations for optimum nutritional management of horses with impaired health or veterinary conditions. Fine-tuned, specific nutritional management is necessary for horses affected with hepatic diseases, renal diseases, metabolic (equine metabolic syndrome, laminitis, pituitary pars intermedia dysfunction) and digestive system problems, particularly colic.
In other species, to ensure the diet at least reaches the lowest optimum level, feeding levels are about 1.3 to 2 times NRC values. And in humans, the recommended daily intakes are two standard deviations above the average minimum requirements – making them appropriate for 98% of people. Applying these adjustments to the horse, the recommended daily intakes would be around 1.2 times the NRC for maintenance and 1 ½ times for growing horses. Ongoing research suggests that horses should be fed 2—5 times the NRC vitamin A levels for growth and reproduction and 2—3 times the NRC-recommended copper intake.
Estimates of the horse’s nutrient requirement and the intake and nutrient content of all the feeds in the diet are found in textbooks. The mathematical drudgery of ration evaluation, equations and calculations has been relieved by development of diet analysis software. There are many programs available which calculate the total diet and or daily intakes, then compare these sets of values with nutritional goals, such as the nutrient requirements of horses. Each program has its own inherent strengths and weakness.
Caution and care are required with mathematical evaluations alone. They do not account for what can be safely fed under different feeding systems. To be as accurate as possible, complete and individualised for each horse, an understanding of equine physiology, feedstuffs and feeding plans is important. For example, the appropriateness of energy intake is commonly assessed by the body condition score which was developed in America to quantify fat cover in pregnant quarter horse mares. It is a blunt instrument when applied to non-pregnant, non-quarterhorse, non-mares.
Nutritional science is often used to determine minimum nutrient requirements — whereas practical nutrition meets optimum ranges for specified purposes. Most diet analysis software for horses uses average values for requirements, compositions of ingredients, and intakes of forages and feeds to produce a single solution, i.e. one diet or one supplement. When diet analyses are performed at Jenquine, we work with your veterinarian as required, and our ranges are based partly on the literature and partly on our own experiences with all manner of horses – i.e. basically anything that whinnies – from all over the world. Factors we consider include geographic location, medical history, exercise, genetics, epigenetics, exercise and discipline, individual metabolism, bodyweight, body composition and body condition.
Fortunately and thankfully, with scientific rigour, the NRC continues to establish optimal ranges. As well as science, practical experience, contributes to the craft, the art, the science and the technology. Our overarching aim every day is to bring this to horses and their owners.
EQUINE CLINICAL NUTRITION
Dr Jennifer Stewart
