Feed Lot Magazine Online, Phosphorus Levels

With respect to phosphorous (P), for many years those of us who practice range nutrition were out of step with what is considered the "gold standard" in nutrition, the National Research Council (NRC). Worldwide the NRC is considered the leading authority on nutrition, and virtually all nutrition software programs use NRC data.

With respect to range cow nutrition, for over 30 years NRC recommended roughly 18 grams of P for maintaining beef cows. Simple observation however, indicated that 85 percent of that recommendation was plenty. That is, even within my own practice there are legions of clients experiencing 90 percent-plus calf crops in herds that received no more than 15 grams of P. In 1996 the NRC recognized the problem and adjusted the maintenance recommendation down to 14 grams.

Recently there has been some work at the University of Nebraska indicating that P recommendations for feedlot rations are likewise excessive. As a practical matter, this is of greater importance than the range recommendation. The reason is that with self-fed minerals it was exceedingly difficult to get cows to eat enough P to meet the previous NRC recommendations. Feedlot rations obviously are a totally different matter. We can put whatever level of P we want into a supplement package to force feed through the ration.

Likewise, while consulting nutritionists were not particularly concerned about the previous NRC cow recommendations and in fact, formulated only to meet the lower levels, that is not true for feedlot work. Due to liability concerns, virtually every consulting nutritionist formulates to meet or exceed NRC. The reason is that should a feedlot experience poor performance, anyone looking over our shoulder would judge the formulation "deficient" by the NRC standard.

It makes no difference whether "low" P was the problem or not, to a layman that would be a fundamental error. Likewise, as mentioned, virtually every computer nutrition program uses NRC data. Therefore any computer "analysis" of your formulation would be deemed deficient.

Call for Research

Phosphorous is usually the most expensive component of mineral supplements, and that alone should behoove us to determine exactly what the requirements are. For research to delineate the exact levels, and the NRC officially adopt them, would give the practicing nutritionist the foundation to lower formulation levels. But there is an even more important reason than cost.

Phosphorous is one of the most critical minerals in terms of potential environmental problems. In many cases the P level in manure is the limiting factor in terms of how much can be applied to farmland, and/or is the most detrimental minerals in terms of fish kills, should run-off occur. For the record it should be pointed out that the beef cattle industry has an excellent record in terms of retaining run-off.

The swine industry, however, has had some catastrophic spills which have focused attention on animal agriculture in general. For this reason, we need to become proactive. For example, the Florida dairy industry has adopted a mission statement requiring that rations be formulated with the minimum of P in keeping with good animal health and production.

Certainly a similar mission statement by our own industry would be good, but we need some unimpeachable research to delineate what the minimum levels are. This would protect professional nutritionists in terms of liability, and let us in-fact formulate to minimum levels.

If we don't become proactive, government regulation might be a consequence. In Australia, for example, it is illegal to add phosphorous to animal feeds. This is strange considering P is an element essential to life.

As a way around such a regulation, we can formulate with feedstuffs naturally high in P, for example wheat midds, brewer's grains, brewer's yeast, etc. Hopefully we can avoid a ban with serious academic research, followed by calculated professional consulting.

Dr. Price has several books and a subscription newsletter available. For more information, call Feed*Lot magazine at 800-798-9515.