Interest continues to grow in the use of insects in poultry and other diets, and while studies continue apace into their nutritional value as a feed ingredient, less attention has been given to the qualities of meat derived from insect-fed broilers.

A couple of studies from Italy, however, have sought to address this lack of knowledge.

A study published this year looked at black solider fly (Hermetia illucens - HI) defatted meal as a dietary protein source for broiler chickens and its effect on carcass traits, breast meat quality and safety, and concluded that slaughtering performance was improved and that there were no detrimental effects on meat quality parameters or heavy metal residues in meat.

Along with a control diet, birds were fed diets corresponding to 50, 100 and 150 grams per kilogram of feed, or 16.56%, 33.01% and 49.63% of required crude protein and slaughtered at 35 days. Their carcasses were then weighed, and the breast meat excised from 16 birds per feeding group for quality evaluation.

Linear and quadratic responses were recorded for increasing meal levels in live bird and carcass weights.

Where breast color was concerned, redness showed a linear response, while yellowness linearly decreased as meal levels increased.

Inclusion of more HI meal in diets resulted in the moisture content linearly decreasing, while the protein content increased. The total saturated fatty acid and total monounsaturated fatty acid proportion rose to the detriment of the polyunsaturated fatty acid fraction.

The researchers concluded that the meal would appear to offer a valuable protein source for broiler chickens when included up to 100g/kg in their diets, leading to improved slaughter performance without detrimental effects on meat quality parameters or heavy metal residues.

The value of fat

Defatted protein meal may be the most appealing feed ingredient, but it is only one of the products that can be obtained from black soldier fly larvae.

Defatting the meal during production will lead to a fat co-product, which could be used in poultry diets as a substitute for commonly used lipid sources, such as rendered fat and vegetable oils, in particular that from soybean.

In a separate study, the effects of 0%, 50% and 100% dietary replacement of soybean oil with HI fat on the quality and sensory characteristics of chicken meat was examined, with supplementation limited to the finisher phase.

The study showed that the replacement of soybean oil with larvae fat is technically feasible, up to 100% substitution levels. Overall results were comparable among the three dietary groups suggesting that HI fat can be considered a promising sustainable ingredient. However, the fat composition of HI larvae is suboptimal for providing healthy meat for humans and, for this reason, further research is needed to solve this drawback.

Meat quality was satisfactory from a nutritional and sensory point of view, suggesting that HI larvae could be considered a possible ingredient for commercial broilers. However, the fatty acid profile of the meat was negatively enriched in saturated fatty acids, mainly to the detriment of the polyunsaturated fatty acid fraction.

However, the researchers noted this could be addressed either through improving the fat composition of the larvae through substrate modulation or equilibrating the lipid quality of the poultry diet through inclusion of ingredients rich in polyunsaturated fatty acids.