Insects can be bred on brewers’ spent grain and leftover bread. Cockroaches and soldier flies are suitable livestock feed.
We’ve got used to the idea of crickets and mealworms on the menu. Now we hear that insects can also make good animal feed.
Dennis Oonincx studied how you can breed them on waste products from the food industry. His choice doesn’t sound too appetizing: soldier flies and cockroaches. ‘They taste bad, yes,’ says Oonincx. But both insect species are very efficient at turning plantbased feed into animal protein, whereas they are not fussy eaters. What is more, they produce little CO2 per kilo of protein and can be produced in a small space. This makes then strong candidates for addressing the projected future shortage of animal protein. Oonincx offered the insects a range of industrial byproducts: a mixture of brewer’s yeast, brewer’s spent grain, leftover bread, cookie waste and potato peel. These byproducts from the food industry are normally processed into livestock feed. A control group was given standard feed used in breeding insects, such as chickenfeed.
The feed conversion efficiency of crickets and mealworms is similar to that of pigs and chickens. That they are more sustainable is down to the fact that they produce smaller amounts of greenhouse gases. The feed conversion efficiency of cockroaches and solder flies is even greater, Oonincx concluded. ‘The pig uses about 20 percent of the plant protein in the feed, the soldier fly about 60 percent. That efficient protein storage makes them an interesting potential link in the chain for livestock feed.’ Oonincx also investigated whether he could breed soldier flies and cockroaches on manure. That could be extremely interesting, because manure has a negative economic value in the Netherlands. But much more research is needed on this. What is more, it is currently illegal in Europe to use insects bred on manure in livestock feeds. Outside Europe, however, Oonincx sees opportunities for breeding insects on manure.
Dennis Oonincx graduated with a PhD on 6 January; his supervisors were professors of Entomology Arnold Huis and Joop van Loon.