Who are the NRC?
In the USA, the National Academy of Sciences have a group of scientists involved in the National Research Council (NRC). This committee has spent many years researching the nutrient requirements for horses.
Not just horses, there are guides for other animals such as dogs and cats, cattle and small ruminants which includes sheep and goats. They are “a private, nonprofit, self-prepetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare” for the purpose of furthering knowledge and advising the US federal government.
The NRC provides the known nutrient requirements for horses by weight, age, workload and reproductive status. Tables are given which set out the minimum requirements to prevent deficiency state symptoms, discussions of each of the nutrients listed, and maximum tolerance levels. The requirements “…indicate the minimum amounts needed to sustain normal health, production, and performance of horses” based on available research. The NRC Committee on Animal Nutrition produced the current 6th revised edition of 2007 Nutrient Requirements of Horses. This is the equine nutrition reference used to find out how much energy, nutrients and minerals should be fed and in what ratios or proportions they should be fed. A horse in America is the same in Australia and elsewhere when it comes to nutritional requirements.
The National Academy of Sciences has provided a useful NRC online program for horses that is freely available and can be downloaded to your computer. This program was developed from equations and other data presented in the 2007 Nutrient Requirements of Horses. It complements the information provided by the NRC by performing some of the procedures needed to calculate requirements. This program requires you to enter specific information such as current body weight, expected mature body weight, month of gestation (for pregnant mares), months of age (growing horses) and months of lactation (lactating mares). For horses at maintenance, you have to choose from the low, average or high categories. Similarly, for exercising horses, you choose from four levels of work load.
For example, the NRC have set the requirements per day for a 500 kg mature horse in light work at 100 mg for copper and 400 mg for zinc. Is your horse getting his daily requirements?
What it can’t do is calculate amounts needed so that the minerals are in the correct ratios or proportions to each other. This is typical of ration ‘balancing’ programs that are online or offered as a service for free by feed companies. To see why this is just as important, if not more important than simply satisfying daily needs, read the page on mineral interactions.
Links to the current editions are below.
Q. The problem with NRC recommendations is that it is based on American soil profiles which are very different to Australian soil profiles. The mineral supplements recommended for American conditions just dont fit Australian ones and can lead to big problems. How can the NRC help us in Australia?
A. The NRC recommendations are not based on soil profiles, they are based on what horses need per day to avoid nutrient deficiency symptoms. In regards to soils, America and Australia are no different in the variation in nutrients that horses get, there is variation in soil and pasture across both countries. Some soils are saline, some are selenium rich, most are copper, zinc and selenium deficient both in America and Australia and elsewhere. If you want to compare soils then look at the top few cm’s that plants derive their nutrients from ,that is, how far down the roots can grow. More importantly it is the pasture/hay that counts as horses eat pasture or the hay that pasture produces. The pasture/hay results that I’ve seen show that the problems they face in America with mineral deficiencies and inbalances are the same in Australia and elsewhere. Horses are horses whether they be in America or Australia. If your horse’s diet is deficient for any nutrients then it is doesn’t make any difference whether the horse is in America or Australia, same principles apply.
Mineral supplements in America and Australia don’t balance any soils as the companies do not know your specific pasture or hay profile. For example, many supplements in Australia have a lot of calcium to deal with the coastal oxalate grass problem, eg. Kikuyu. However, not all horse owners have to deal with oxalate grasses and if you have a lot of Kikuyu or Seteria then the standard dose usually recommended will not provide enough calcium. With oxalate grasses like Kikuyu, Setaria, Buffel and Humidicola it’s best to assume a worst case scenario of 100% blocked calcium.