A chicken diet that partially consists of silkworm meal has no negative effects on production, and can be effectively used at any growth stage – adding further weight to calls for the insects to be more widely used in commercial livestock production.
Silkworm (Bombyx mori) pupae are currently considered a waste product of the silk industry. But with previous research showing that meal made from the pupae has higher protein content than soybean meal and fishmeal, with abundant omega-3 fatty acids, its use as an animal field has been mooted as a more sustainable approach.
New work by researchers in Hungary and Italy explored feeding a diet consisting of 4% silkworm meal, with the remainder soybean meal, to Ross broiler chickens at different stages of their growth. A soybean-only group of birds served as a control.
Although a number of studies have explored feeding silkworm to chickens, this was the first time the role of feeding stage on production outcomes had been analysed.
Performance unaffected by insect inclusion
They found that growth performance, as well as carcass and meat traits, were similar across the three groups. However, the nutritional quality of the birds’ meat was improved by its inclusion at the grower-finisher phase, when compared to its use as a starter diet.
“Results of the present study highlighted that carcass, breast, and leg yields were not affected by the dietary inclusion of 4% silkworm meal, which is in line with findings of other studies on silkworm meal as protein source for chickens,” they wrote in a report published in the journal Animals.
“The same was not always observed when different insect species (black soldier fly, mealworm, house fly) were tested, which might be attributable to different protein quality and/or efficiency of amino acid utilization.”
Questions remain on moisture, sensory aspects
The researchers also noted a greater moisture loss associated with birds fed the silkworm diets, from the breast meat during thawing and leg meat through dripping when suspended. The difference could be attributed to different fatty acid profiles, they suggested, while calling for further investigations to confirm this.
“To the best of our knowledge, this is the first study that reports the effects of silkworm meal dietary inclusion for chickens on the water holding capacity of meat,” they added.
Additional research could explore the impact of including silkworm in the diet of chickens on the meat’s fatty acid profile and the sensory response of consumers, said the scientists, to generate further evidence ahead of a possible move into the mainstream feeds market.
