Chemical composition and contents of amino acids and fatty acids in the planktonic cladoceran Daphnia magna were investigated, aiming to evaluate its value for feeding of young carp. Crude protein, crude fat, crude fibre, ash and moisture contents were analyzed according to standard laboratory procedures.
Amino acids content was determined by LKB 4101 automatic analyzer and that of fatty acids by Chrompack CP 9000 chromatograph, using a flame ionizing detector. Protein contents amounted to 1.18 and 39.24% of fresh and dry mass, respectively. These amounts of proteins completely meet nutritional requirements both of carp fry and its older categories and other omnivorous fishes. Raw fat and fibre contents in dry weight were 4.98 and 4.32%, respectively, which is suitable for the commercial carp breeding. Methionine and phenylalanine are partially in deficit, whereas other essential amino acids identified in dry mass of Daphnia magna were present in amounts adequate for all carp categories. The proportions of saturated and unsaturated fatty acids in lipids of Daphnia magna were 18.70 and 66.20%, respectively. Among the unsaturated fatty acids, the omega–3 group was present with 27.30%. The omega–3 : omega–6 fatty acids ratio was 5.68:1, which fully meets the carp nutrition requirements.Istraživanja kemijskog, aminokiselinskog i masnokiselinskog sastava planktonskog račića Daphnia magna obavljena su radi utvrđivanja pogodnosti za hranidbu šaranske mlađi. Sadržaj sirovih bjelančevina, masti, vlaknine, pepela i vlage utvrđeni su uobičajenim metodama. Sadržaj aminokiselina određen je LKB 4101 automatskim analizatorom, a sadržaj masnih kiselina Chropack CP 9000 kromatografom s pomoću plamenoga ionizirajućeg detektora. Sadržaj bjelančevina u svježoj tvari iznosio je 1,18 %, a u suhoj tvari 39,24 %. Navedene vrijednosti bjelančevina u potpunosti odgovaraju hranidbenim potrebama mlađi i starijim kategorijama šarana i drugih omnivornih riba. Količina sirove masti u suhoj tvari iznosila je 4,98 %, a vlaknine 4,32 %, što odgovara potrebama konzumnog šarana. Od esencijalnih aminokiselina u suhoj tvari Daphnia magna, fenilalanin je djelomično nedostatan dok su ostale esencijalne aminokiseline zastupljene u pogodnoj količini za sve kategorije šarana. Količina zasićenih masnih kiselina u masti Daphnia magnae iznosila je 18,70 %, a nezasićenih 66,20 %. Od nezasićenih masnih kiselina, omega–3 masne kiseline zastupljene su s 27,30 %. Odnos omega–3 i omega–6 masnih kiselina iznosio je 5,68:1, što u potpunosti odgovara hranidbenim potrebama šarana
