Influence of substitution of sunflower oil by different oils on the growth, survival rate and fatty acid composition of Jamaican field cricket (Gryllus assimilis)

Abstract

This study was performed to investigate the influence of linseed, fish, pumpkin seed and sunflower oil on the Jamaican field cricket’s survival rate, growth and fatty acid profile. Fatty acids were analysed by gas chromatography mass spectrometry as fatty acid methyl esters in the homogenates of whole crickets. Survival rate was influenced by oil type and oil content. With an increase in the pumpkin seed and linseed oil percentage survival rate decreased (from 45.3 to 34.0% for the pumpkin and from 36.7 to 24.12% for linseed), while with an increase in fish oil, the survival rate increased (from 30.7 to 45.4%). Oleic acid and total monounsaturated fatty acids had the strongest positive effect on cricket survival and polyunsaturated/monounsaturated fatty acids ratio had the highest negative correlation with cricket survival. The most abundant fatty acids in all groups were linoleic, oleic and palmitic. The levels of individual fatty acids varied considerably between different treatments. Linseed oil significantly increased the content of linolenic acid (7.32% for 3% supplementation to 11.27% for 5% supplementation) and strongly decreased the n6/n3 ratio, but the EPA and DHA content was not detectable. In the fish oil fed crickets EPA and DHA content was detectable ranging for EPA from 0.78 to 1.35% and for DHA from 0.16 to 0.29% and the n6/n3 ratio was decreased. In the pumpkin seed and sunflower oil treated insects the n6/n3 ratio was very high due to the high content of linoleic acid. In conclusion, dietary linseed and fish oil could be an interesting strategy to manipulate cricket fatty acid profile to make them more interesting from a nutritional standpoint. Monounsaturated fatty acids have a positive influence on cricket survival, and therefore, they should not be neglected in feed formulation for large scale cricket production.