Millions of chickens in Delaware have been on a diet with aim of reducing their impact on the environment and improving the health of the state’s waterways.
Research led by William Saylor, a professor of animal and food sciences at the University of Delaware, has confirmed that the chickens in the area are now digesting more of the phosphorus, an essential nutrient, in their feed, due to the addition of phytase, a natural enzyme. This has resulted in 23% less phosphorous in chicken manure.
Poultry litter is often used to fertilise farm fields. But now, much less phosphorous is present in the litter and therefore much less phosphorous is being absorbed into the ground.
This is good news for the waterways. Overloads of nutrients, particularly phosphorus and nitrogen, have contributed to serious water-quality problems, such as massive blooms of algae and fish kills.
In 2006, Delaware farmers produced over 269 million broiler chickens, according to the Delmarva Poultry Industry. This translates into 280,000 tonnes of waste. And, according to recent analyses by David Hansen, a UD assistant professor of soil and environmental quality, there is now about 19 pounds of phosphorus in a tonne of Delaware poultry litter. This compares with 25-30 pounds of phosphorus per tonne of litter just five years ago. The 30-40% reduction is credited to phytase-modified diets and other nutrient management practices adopted by poultry farmers under Delaware’s Nutrient Management Law of 1999. That reduction means that the phosphorus load to the environment has been reduced by some 2-3 million pounds per year.