The present research studied the effect of a dietary inclusion with Hermetia illucens larvae meal (Hi) on rainbow trout’s fillets chemical composition. The effect of Hi inclusion in diets on rainbow trout chemical characteristics was evaluated. Trout were fed three different diets: control (C, no Hi inclusion), 25% and 50% of substitution of fish meal with Hi (Hi25 and Hi50, respectively). Fillets were analysed to quantify proximate composition, carbohydrates percentage, colour parameters, nucleotides concentration, fatty acids profile, volatile organic compounds (VOCs) and myofibrillar and sarcoplasmic concentrations. Diets did not affect proximate composition. Contrariwise, Hi50 diet decreased fillet yellowness and both substitution percentages affected negatively adenosine monophosphate concentration. Saturated fatty acids, mostly C12 : 0, increased their contents in relation with Hi inclusion at the expense of monounsaturated and polyunsaturated (both n-3 and n-6) fatty acids. Less modifications were reported in VOCs as only heptanal and octanal concentrations were affected, no new compounds appeared in relation with Hi inclusion. No modifications in proteins patterns were shown even if myofibrillar content decreased in trout fed Hi50. The results highlighted that chemical modifications occurred in fillets were related to the chemical composition of the H. illucens meal and to the percentage of inclusion in the diet. Substitution of fish meal with a precisely percentage of H. illucens meal could be a potential future solution in order to decrease the quantity of fish meal used in aquafeeds.

The effect of the stage of lactation, the number of foals and age of the mare on changes in the fat content and fatty acid composition of colostrum and milk of primitive Konik horses was investigated. Colostrum and milk samples from 12 lactating mares were collected at the beginning of lactation, on the days 1 and 2 after foaling and then, starting from the first month of lactation, at 4-week intervals up to the sixth month of lactation. Significant differences were observed in fat content as well as the composition of some analysed fatty acids between colostrum and milk of mares of the Konik breed. The number of foalings and the age of mares did not have a statistically significant effect on the fat content in milk and had only a slight effect on the fatty acid composition. Milk produced by mares of the Konik breed is characterized by a considerable content of polyene fatty acids with 18 carbon atoms, a low ratio of n-6 fatty acids to n-3 fatty acids as well as low, highly advantageous values of atherogenic and thrombogenic indices.