Aug. 12, 2013
Greening manure could yield fly larvae fit for a meal
Two negatives – cow manure and flies – can make a positive. Cornell animal scientists, entomologists and a business professor will examine the environmental impact and commercial potential of quickly processing dairy cow manure with fly larvae. And then using the dried larvae to feed other farm animals.
For dairy farms, manure waste presents an ongoing disposal challenge, while at the same time, the common housefly is considered a public health problem. With a 2013 grant from Cornell’s David R. Atkinson Center for a Sustainable Future, the professors hope to exploit the housefly’s life cycle and hasten manure’s decay process – to make it into a usable fertilizer in as little as eight days. The residual larvae may then be dried and made into meal – high-quality protein supplements for aquaculture and livestock.
“Manure is a natural substrate for fly larvae. We can decrease manure volume, control for nutritional content and decrease its potential for eutrophication (leached, heavy doses of nutrients in water bodies),” said Vimal Selvaraj, assistant professor of animal science and the principal investigator on the grant. Co-researchers are Patricia Johnson, professor and chair of animal science; Jan Nyrop, professor of entomology and senior associate dean of the College of Agriculture and Life Sciences; and Mark Milstein, clinical professor of management at the Samuel Curtis Johnson Graduate School of Management and director of the school’s Center for Sustainable Global Enterprise.
Nyrop will examine larval-growing density; Johnson will study how the larval proteins affect the diets of broiler chickens; and Milstein will examine the larvae meal’s market potential and the costs of scaling up commercial operations.
Looking toward 2050, the Food and Agriculture Organization of the United Nations says the world must double its food output over the next 30 years – by reserving more grain for humans, exploiting insect proteins and supplementing animal feed without dipping into humans’ food.
Flies and manure have long enjoyed harmony. Female flies can ovulate up to 700 eggs during a life cycle, and the larvae thrive on decaying waste. An army of flies can reduce manure mass by half, concurrently lowering manure’s nitrogen and phosphorus content. Meanwhile, the residual larvae can be harvested as farm feed teeming in protein and essential amino acids.
While collected larvae will be dried and ground into meal to replace soybeans or fishmeal in animal feed, additional toxicological safety testing for heavy metals, residual drugs and antibiotics will be examined.