Larvae of the black soldier fly (Hermetia illucens), pictured here in its adult stage, can make for an effective source of protein in animal feed. A new study in Kenya finds an improved cost-benefit ratio and return on investment for chicken farmers using fly meal compared to soybean- or fish-based feed. (Photo credit: Johnny N. Dell, Bugwood.org)

By Meredith Swett Walker

Chickens of yore foraged for most of their own food, hunting and pecking around the farm and eating plenty of insects—which provided protein—as well as spilled grain and kitchen scraps. Now that most chickens are raised on larger, specialized farms, insects are not a big part of their diet. They are fed commercial chicken feed, which typically contains protein derived from soybeans or fish. These days, the only chickens that get to eat insects are pricey free-range birds or pampered backyard hens.

Meredith Swett Walker

But that could change. In a study published in May in the Journal of Economic Entomology, Victor Ogeto Onsongo and colleagues examine whether fly larvae could replace soybeans or fish meal as a protein source in commercial poultry feed. This research was conducted at the Poultry Research Unit of the Kenya Agricultural and Livestock Research Organization, with colleagues from the University of Nairobi, the International Centre of Insect Physiology and Ecology in Nairobi, Kenyatta University, as well as Makerere University.

As human populations increase, so does our demand for meat, including poultry. This increases demand for soybeans and fish meal to produce poultry feed. But many countries, including Kenya, do not produce enough soybeans and must import them. And demand for fish meal has led to overfishing in Lake Victoria and other areas. Poultry feed is costly to farmers as well as the environment. Feed accounts for about 60-70 percent of production costs for some poultry producers.

Black soldier fly larvae (Hermetia illucens) could provide a solution. The larvae are a more environmentally friendly source of protein, as they can be raised on various organic waste materials and require less water than soybeans. The larvae’s waste, or frass, can be used as an organic fertilizer. And black soldier flies don’t bite or transmit disease.

They’re good for chickens and farmers, too. Insects have a more nutritious amino acid composition than soybeans, and the chitin in their exoskeletons may help support the immune system. And, using insect meal in poultry feed may help reduce its cost.

Black soldier fly larvae (Hermetia illucens) can be raised on various organic waste materials and require less water than soybeans. The larvae’s waste, or frass, can be used as an organic fertilizer. And black soldier flies don’t bite or transmit disease.
And, when used for animal feed, insects have a more nutritious amino acid composition than soybeans. (Public domain image)

Onsongo and colleagues raised chicks from one day old to butchering age on conventional starter and finisher feeds as well as feeds containing three different amounts of meal made from black soldier fly prepupae. Nutritional composition of the fly meal was analyzed. Birds’ body weight and feed intake was monitored to calculate the feed conversion ratio, a measure of how efficiently feed is converted into meat.

At the end of the experiment, chickens were humanely butchered and cuts of meat and internal organs were weighed and measured. Samples of the meat were cooked and tasted by volunteers to determine if consuming fly meal affected flavor of the chicken. Researchers also performed a cost-benefit analysis and calculated return on investment to compare conventional feed with feed containing fly meal.

The researchers found that replacing soy or fish meal in poultry feed with fly meal (up to 42 percent in the starter diet and 55 percent in the finisher diet) did not have any adverse effects on weight gain, body composition, or flavor of chickens. But it did reduce the cost of feed and improved the cost-benefit ratio by 16 percent and the return on investment by 25 percent.

Incorporating black soldier fly larvae into feed has the potential to reduce the environmental costs of poultry production as well as help farmers by reducing feed prices. Unfortunately, there is very little fly meal commercially available in East Africa. This research could help convince poultry feed manufacturers to use black soldier fly meal as a protein source. If a market for the insects opens up, commercial production of black soldier flies could create jobs as well as environmental benefits in Kenya and other countries.

Meredith Swett Walker is a former avian endocrinologist and wannabe entomologist. She now studies the development and behavior of two juvenile humans in the high desert of western Colorado. When she is not handling her research subjects, she writes about science and nature. Find a sampling of her work at www.magpiescicomm.com.