Oxenboll, 2011 – Use of a Protease in Poultry Feed Offers Promising Environmental Benefits

Enzymes are widely used in feed to improve utilization of nutrients and it is generally acknowledged that phytases, by improving phytate phosphorus utilization are an important tool to reduce phosphorus pollution and the environmental problems derived from this such as eutrophication. Lately, the use of proteases as feed enzymes has gained interest. Proteases are added to feed with the purpose of increasing dietary protein hydrolysis and thus enabling improved nitrogen utilization. When animals utilize nitrogen better, there is a possibility to decrease the diet protein content and in turn also reduce the content of nitrogenin manure. The environmental consequences of decreased dietary protein content and reduced nitrogen excretion were investigated in a Life Cycle Assessment (LCA), which considered all steps in broiler production from production of feed ingredients, to the broilers leaving the chicken house, including the use of manure. Wide ranges of environmental impacts were analyzed, covering emissions of nitrous compounds to both air and the aquatic environment. Significant benefits were obtained for all impacts considered. Most important were the benefits related to reduced emissions of ammonia, which help reduce both health risks and environmental impacts, such as acidification and eutrophication. The largest effects were obtained when protease was used as a tool to allow for lower diet protein content. However, even when used in a diet with normal protein level significant benefits were observed. It is illustrated that the use of protease can contribute significantly to current efforts to reduce nitrogen emissions from livestock production.