Replacement of soybean meal with sesame oil-cake in the rainbow trout (Oncorhynchus mykiss) diet and its effects on growth indices, nutrition, fillet biochemical compositions, and liver enzymes

In the present study, the effects of the different levels soybean meal replacement with sesame oil-cake in rainbow trout diet on growth performance, body biochemical composition and liver enzymes were evaluated. An 8-week feeding period were performed by Four experimental diets with different levels of sesame oil-cake 0% (S0), 5% (S5), 10% (S10) and 15% (S15), respectively, in a completely randomized design in triplicate. Growth and nutrition indices including final weight (FW), specific growth rate (SGR), weight gain (WG), feed conversion ratio (FCR), lipid efficiency rate (LER) and feed intake (FI) did not show significant differences between different treatments (p<0.05). However, there was a significant difference between S10 (0.23) and S15 (0.21) treatments in protein efficiency rate (PER). In contrast, hepato somatic index (HSI), visceral somatic index (VSI) and condition factor (CF), showed significant difference (p<0.05) between experimental treatments, so that most of them were related to the treatments (S10= 1.07), (S10= 6.29) and (S15= 1.05, respectively, and the lowest of them were observed in the treatments (S15= 0.98), (S15= 5.78) and (S0= 1.02), respectively. There was a significant difference in fillet protein, lipid and moisture (p<0.05) but the amount of ash did not show any significant difference. In addition, the activity of alanine amino transferase and aspartate amino transferase showed a significant decrease with increasing sesame meal and conversely, the activity level of alkaline phosphatase increased significantly with increasing replacement level (p<0.05). According to the results, it can be stated that not only the use of sesame meal instead of soybean meal up to 15% did not have a significant effect on rainbow trout growth and nutritional indices and also improved the health status and quality of the fillet biochemical composition.