A recent Feed Management article highlighted the problems of including excess protein in broiler diets. Providing more protein than the required amount in feed has become a common practice that producers and nutritionists believe maintains costs low, but, actually, increases them, since this results in reduced broiler productivity and health.
Even though it’s overwhelmingly clear that broilers, and all animals, require amino acids (not protein), providing “safety margins” in many commercial formulas is still common. Often, nutritionists and producers formulate more than the required amount because of concerns with increasing days to market – adding a few more days before you ship the birds and clean out the barns means that fewer total birds each year will be marketed.
On the surface, it’s not illogical to think this way because differences in amino acid digestibility among and between ingredients exist and can hinder performance when the digestible supply of amino acids is reduced for some reason. In addition, changes in production practices, such as the reduction or elimination of antibiotics, are adding uncertainty to broiler performance. So, ultimately, it seems to make sense to put some extra protein (amino acids) in a formulation.
However, there are three main problems with this line of thinking. First, there is no way to store excess amino acids and getting rid of them truly represents a cost to the bird. Nitrogen in protein goes through an elimination process and must be excreted, costing energy. Energy, in absolute terms, is the most expensive portion of a diet, so overfeeding protein could, in fact, reduce the energy available for productive growth and increase your days to market, too.
Second, some excess protein passes though the digestive tract to the hindgut where it is fermented. Fermentation of proteins favors pathogenic bacteria that can cause disease outbreaks in the flock and combining this with reducing or eliminating antibiotics could spell trouble.
Third, incorporating excess protein results in increased water consumption by the birds. The article notes that for every 1 percent of excess dietary protein consumed, water intake increases by about 3 percent. Not only does this increase resource use for millions of birds, but will also result in “wet litter”, which has significant animal welfare effects.
Finally, like energy, protein is expensive and should be included only where cost-benefit analysis (i.e., more lysine equals more growth) indicates. In addition, as I’ve written about before, excessive nutrients in feed can be externalized into the surrounding environment. This can result in the water becoming contaminated with nitrogen from excessive dietary protein and leaving the farm, affecting others and resulting in conflict.
Overall, strategies that keep more amino acids in the animal will be good for both the bottom line and the environment. Using high-quality, highly-digestible amino acid sources, such as properly-processed extruded soy meal, will help accomplish this. In addition, lower-protein diets containing synthetic amino acids, like L-lysine, will be able to maintain performance with less protein. When utilizing the extrusion process to produce feed, the risk of feeding excess protein along with the chances of externalizing any chemicals into the environment can be reduced.