The fortification of feed is known to be a useful tool to manipulate the nutritional value of insects. This study aimed to reveal the effect of carrot supplement duration on the basic nutrients, fatty acid profile, carotenes, and tocopherols. Jamaican crickets (Gryllus assimilis) were provided with chicken feed supplemented with carrots ad libitum for 0, 3, 7, 14 and 60 days prior to harvest. The supplementation increased the levels of α-carotene and β-carotene in the insects. The content of carotenoids did not significantly differ between groups fed carrot for 14 (α-carotene = 13.7 μg/g DM; β-carotene = 34.6 μg/g DM) and 60 days (α-carotene = 15.2 μg/g DM; β-carotene = 37.2 μg/g DM), suggesting that the capacity of the insects to store carotenes is limited. Some carotenoids (α-carotene = 5.4 μg/g DM; β-carotene = 12.8 μg/g DM) were found in crickets given carrot supplementation for only 3 days prior to harvest. Carrot supplementation affected the fatty acid profile of the insects. Crickets fed carrot for 60 and 14 days contained lower levels of SFA (32.00 and 32.74% of total fatty acids respectively) and higher levels of PUFA (33.06 and 32.49% of total fatty acids respectively) in comparison with insects fed for 0, 3 or 7 days. No influence of carrot supplementation was observed in feed conversion, tocopherols and basic nutrients (proteins, lipids, ash). Conclusively, the paper showed some beneficial effects of carrot supplementation, when the highest levels of carotenoids were reached by 14 and 60 days of carrot provision. Therefore, the whole life supplementation seems to be not necessary to reach the increased content of carotenoids in crickets.
An ex situ breeding programme for the endangered UK population of the field cricket Gryllus campestris
