The Study of Relation of Chemical Blend, Diet Fatty Acids and Filet of Oncorhinchus mykiss in the Growth Period

In this survey, the influence of protein diminution and increscent of diet lipid on chemical blend and fatty acids of filet (in three weights, 10-25 gr, 25-75 gr and 130-300 gr) in Oncorhynchus mykiss was studied. Accordingly, between the total length, and standard length and the weight of three filets, there was a great difference (P >0. 05). The maximum amount of protein (18. 6%) found in 150-250 gr filets and its lipid was 2. 3%. The minimum amount of protein (17. 05%) was measured in 15-25 gr filets with 46. 2% lipid. The maximum amount of ash in 150-250 gr size was 1%, and its minimum amount was measured in 50-70 gr size as 0. 53%. As for the saturated fatty acids (MUFA), the maximum amounts were measured in the filet of 150-250 gr fishes, and its minimum amount was found in the filet of 15-25 gr fishes (P>0. 05). In fatty acids (PUFA), the maximum amounts of these acids were measured in filet of 150-250 gr fishes, and its minimum amount was in filet of 15-25 gr as (0. 27%). This proportion (DHA/EPA) showed that the increase of size of fish is caused this proportion to be increased. The diminution of diet protein had no negative effect on the growth of fish, and as for the cost of protein, it can be decreased in diet and replaced with lipid. O. mykiss especially, 130-300 gr filets because of having valuable protein and fatty acids, in contrast to two another filets (15-25 gr and 50-70 gr) are very valuable in feeding.