Histological and fatty acids changes in Caspian salmon (SalmotruttacaspiusKessler, 1877) fed diets with different levels of vitamins E and highly unsaturated fatty acids (HUFA)

In this study, the combined effect of different levels of dietary n-3 HUFAs with α-Tocopherol on changes in the structure of intestine and pyloric caeca and fatty acids profile of Caspian salmon, Salmotrutta caspius, fry (initial weight of 600 ± 25 mg for 10 weeks) were investigated. Six experimental diets containing three different dietary levels of n-3 HUFAs (Low: 1 0.5, DHA EPA, Medium: 2 1, DHA EPA, High: 4 2, DHA EPA g/100g diet) with two different levels of α-Tocopherol (Low: 300 and High: 1000 mg/kg diet) were prepared and named: LL, LH, ML, MH, HL, HH (HUFA/α-Tocopherol), respectively. The results showed that increase in dietary vitamin E increased HUFA levels in polar lipids, particularly when dietary HUFA were higher. Histological analysis showed the mean length of enterocytes had not significant difference in anterior intestine and pyloric caeca segments. However, in fish fed moderate and high HUFA diets enterocytes were slightly higher. Feeding Caspian salmon fry with moderate and high levels of omega 3 HUFA increased the villi area of mucus layer in anterior intestinal. The results of this study showed a concomitant increase in dietary omega 3 HUFA and vitamin E increased long chain fatty acids, especially in moderate and high levels of HUFA fatty acids, which these fatty acids have beneficial effects on the growth and health of fish.