If a little is good, then more must be better, right? Not always, and especially not when it comes to feeding your animals. This article describes a basic concept of feed management, and why you might want to take a closer look at the practice on your dairy. Overfeeding nutrients results in higher feed costs and potentially negative consequences for your animals and the environment.

Phosphorus is a great example of “too much of a good thing.” During the 70s, 80s and early 90s, many researchers, nutritionists, veterinarians and producers were under the impression that increased phosphorus was necessary for reproduction, milk production, and animal health. As an example, the basic lactating cow diet without added mineral contains 0.40 percent phosphorus, well above the requirement for the highest-producing cow.

However, phosphorus was added to rations with total levels often exceeding 0.60 percent. Phosphorus fed above the requirement leaves the animal in feces and urine. In a survey conducted in the Northeast and Mid-Atlantic regions of the U.S. in 2002, on average, phosphorus in rations exceeded NRC guidelines by 34 percent. The extra phosphorus finds its way into the lagoon, then to the field, and in some situations to surface waters.

Surface waters are where excess phosphorus causes serious environmental problems. Algae growth is limited by a lack of phosphorus. When phosphorus is present in high concentrations, algae flourish and consume all the oxygen (thus killing oxygen-dependent life).

Regardless of milk price, everyone is concerned with maximizing the amount of milk produced while decreasing costs of production. In an attempt to achieve the greatest production, it is easy to fall into the trap of, “more must be better!” Take a step back, and keep the animal’s requirements in mind.


Here are some ways to make sure your animals are getting what they need in their diet, and you’re keeping costs down while minimizing impacts to the environment:

  1. Calculate feed efficiency (FCM per pounds of dry matter fed).
  2. Feed for stage of lactation and intake.
  3. Balance rations according to animal requirements and minimize the amount of nutrients leaving in the manure.
  4. Measure (and monitor) MUN (milk urea nitrogen) as an indicator of protein efficiency.

A word of caution – feeding excess of a nutrient decreases the nutrient utilization efficiency, thus increasing excretion of the nutrient into the environment and increasing cost of production. Because of the current economic conditions, many producers are trying to cheapen rations by dropping ingredients. However, simply cutting ingredients because they “cost too much” will not benefit you in the long term and may result in a scenario you cannot recover from.

Feeding cows based on their nutrient and energy requirements is the best approach. Every cost must be evaluated against its benefits, both short and long term. PD

Excerpts from University of California Dairy Newsletter, January 2010

Jennifer Heguy