Global consumption of animal protein—milk, eggs, meat, and fish—is likely to rise 60 to 70 percent by mid-century. But producing food for animals already eats up three-quarters of all agricultural land and threatens to empty the seas for fishmeal. Meanwhile, pig and poultry operations have become notorious for polluting the surrounding countryside with manure.
What’s the answer? Eating fewer animals could help, especially in meat-gorged nations such as the United States, but it isn’t going to make these problems go away. Much of the increased demand will come from developing nations, because of population growth and growing wealth in places such as China and India.
Instead, insects may be the answer. We’re not talking about direct consumption as human food. The truth is that most people are never going to want to throw a housefly burger on the grill. But insects might just be the perfect feed for livestock.
A new article in the journal Animal Feed Science and Technology notes that insects literally breed like flies and are highly efficient (because they are cold-blooded) at converting their feed into body mass. Though it may need to be supplemented with calcium and other nutrients, that body mass is rich in the proteins and fats animals need. But the best part—questions of squeamishness aside—is that insects can thrive on manure and other waste.
The article reviews the state of research on livestock use of locusts, grasshoppers, crickets, black soldier fly larvae, housefly maggots, mealworms, and silkworms. Each has advantages and disadvantages in different habitats and for different species, but together they offer a battery of alternatives to conventional soybean and fishmeal feed.
For instance, black soldier fly larvae—not to be confused with the black flies that are a notorious summertime nuisance in some northern states—avoid human habitats and foods and carry no diseases. They can outcompete some other noxious insects, cutting housefly populations on pig and poultry manure by up to 100 percent. Meanwhile, they can reduce pig or poultry manure itself by 50 percent without requiring any extra energy, at least in warmer climates. They can also slash rotting fruits and vegetables, coffee bean pulp, distillers grains, fish offal, and other food wastes by up to 75 percent, according to the article.
Black soldier fly larvae are already commonly sold as pet food and fish bait. Studies suggest that pigs and poultry could do as well or better on a larvae-based feed as on soybean and fishmeal feeds. The larvae could also be a practical alternative on fish farms, particularly where customers object to feeding fish other fish. For some fish and for poultry, eating insects may also be a lot closer to their natural diet than are conventional livestock feeds.
But is it safe to feed manure-reared larvae to animals that we eat—not just pigs and chickens but catfish, tilapia, turbot, and shrimp?
Harinder Makkar of the Food and Agriculture Organization and his coauthors report that black soldier fly larvae “modify the microflora of manure, potentially reducing harmful bacteria such as Escherichia coli 0157:H7 and Salmonella enterica. It has been suggested that the larvae contain natural antibiotics.” More research will be needed, of course. But the demand for animal products, together with the sharply increasing cost of conventional feeds, means that livestock producers are likely to be interested.
Meanwhile, consumers should prepare themselves to put their forks into rainbow trout fed on a diet in which half the normal fishmeal is replaced by “dried ground black soldier fly prepupae reared on dairy cattle manure enriched with 25 to 50 percent trout offal.”
It may make the world a better place. But it will require the marketing genius of some future Don Draper to make it sound appetizing.