Larvae: Healthy for the Environment, Healthy for You!

Dr. Ali Khan, an entomologist (bug guy) with Alberta Agriculture, Food and Rural Development has developed a technique for recycling oat hulls (a by-product of the milling industry) into a potential feed supplement for poultry. Oat hulls, which have almost no nutritive value when fed to livestock, are used to grow housefly (Musca domestica) larvae. The larvae require no extra feed and can be fed to poultry as a protein supplement.

So why feed flies to poultry?
The larvae growing process has potential as a sustainable agricultural practice - it converts a waste product of the feed milling industry into a highly nutritious product. But how does fly larvae stack up against more conventional poultry feeds? Birds commonly eat insects in the wild, so one would expect that a diet containing insects could be readily used by poultry. That's exactly what a recent University of Alberta study aimed to discover. Previous research indicated that housefly larvae contain 4291 kcal/kg of energy and 59% crude protein. This is quite impressive when you consider that wheat contains 3000 kCal/kg of energy and 13% crude protein. Soybean meal contains 3500 kcal/kg energy and 47% crude protein. Turkey poults (toms) were chosen for the project because their high requirements for protein (28-30%) meant that they were most likely to be fed larvae commercially. The high protein requirement of the turkeys also made it easier to design a balanced feed ration using such a concentrated feed ingredient. A standard corn-based diet was compared to a diet containing 7% dried and ground larvae by weight. Both diets were formulated to include 30% crude protein and 3000 kcal/kg of energy. The toms were raised from hatch to 35 days of age in groups of two, fed ad libitum on their separate diets. During the study there was no significant difference in body weight between the low and the control group birds. The control group, which was fed no larvae, had a body weight of 978.6g at slaughter (35 days) whereas; larvae bird group had a body weight of 949.5g at slaughter (35 days). After the trial, the toms were slaughtered and dissected. Feed conversion efficiency (calculated as kg feed required for a kg of gain) was measured along with growth rate and carcass composition (relative weights of body components). There was no difference between the groups in any of the measurements that were assessed. This suggests that turkeys fed larvae as a protein source will perform just as well as turkeys fed a conventional diet.

Is fly larvae safe?
Since producers are paid based on the total weight of birds shipped it is important that the greatest number of birds possible are shipped to the slaughter plant so that producer returns are maximized. In our study there was no difference in mortality between the control group (1 dead) and the larvae fed turkeys (1 dead). This demonstrates that mortality should not increase as a result of supplementing a turkey diet with fly larvae.

So should I feed flies to my birds?
So does this mean that you should start feeding larvae right now? Not quite. The cost to grow larvae in this manner is extremely high but further development of the process will hopefully decrease the price of larvae in the future.

Who will want turkey that ate fly larvae?
What about the consumer? Research conducted at the University of Alberta investigated the best way to market turkeys fed insects. The study included a taste panel where consumers could comment on the characteristics of meat from turkeys that had been feed larvae.

Take home message
Insect larvae is a feed ingredient that will meet the high energy and protein requirements of turkeys. There was no difference observed between the group of turkeys fed a corn based diet and those fed a diet containing larvae. If the cost of larvae can be decreased, larvae will provide a useful alternative to conventional protein sources while enhancing the sustainability of agriculture.

M.S. Kohle, K. Lewchuk and N. J. Wolanski

Poultry Research Centre News Vol 10 No 2, October 2001