Effects of dietary soy isoflavones on estrogenic activity, cortisol level, health and growth in rainbow trout, Oncorhynchus mykiss

Abstract

Soy isoflavones (the phytoestrogens genistein, daidzein and glycitein) may act as estrogen receptor agonists or antagonists. The aim of this study was to examine the effect of dietary isoflavones on growth, reproduction and health in rainbow trout (Oncorhynchus mykiss). Rainbow trout fed three experimental diets containing different concentrations of isoflavones (0, 500 and 1,500 ppm). Growth, estrogenic activity, plasma estradiol levels, gonadal development, state of stress and histological changes in selected tissues were evaluated at the end of 70 days. Neither growth performance nor the relative mRNA levels of Insulin Growth Factor I (igf‐I) in the liver were influenced by different levels of dietary isoflavones. Plasma and liver vitellogenin (VTG) protein levels and plasma 17‐β‐estradiol (E2) were unaffected by treatments, although the correlation between plasma levels of E2 and VTG densitometry values was significant (p < .05). The fish gonadosomatic index (GSI) did not significantly differ among the three experimental groups but correlated with plasma VTG densitometry values (p < .05). Plasma, muscle and fin cortisol concentrations fell within the normal welfare range and were not correlated with isoflavone levels. Histologically, the distal intestine showed a normal morphology with well‐differentiated enterocytes and in the liver hepatocytes were also normal. A supranuclear accumulation of lipid droplets in enterocytes and some lipid droplets in hepatocytes were observed in all tested groups, suggesting an impact of basal dietary lipid on transport/metabolism of fat in the fish. Overall, the present results suggest that the doses of isoflavones tested do not compromise rainbow trout reproduction, growth and health.

Effects of resveratrol and genistein on growth, nutrient utilization and fatty acid composition of rainbow trout

“…Though the feed intake in G-fed fish was reduced, the utilization of protein (PER and PPV) was significantly enhanced, leading to growth rates comparable to the control-fed groups (Table 3). Estrogen-like secondary plant compounds can affect growth and other physiological parameters in fish depending on the species or developmental stage investigated (Cleveland and Manor, 2015;Pastore et al, 2018). Possibly, the estrogenic properties of G might have caused the slight alterations in nutrient utilization and growth as observed within this study.…”

Effects of dietary soy isoflavone and soy saponin on growth performance, intestinal structure, intestinal immunity and gut microbiota community on rice field eel (Monopterus albus)

“…This phenomenon was similar to study that high level of soy saponin decreased growth performance on juvenile Japanese ounder (Paralichthys olivaceus) [7] . While dietary soy iso avone has the negatively affect growth performance on Atlantic salmon (Salmo salar L.) [12] , dietary soy iso avone not signi cantly in uence growth performance on rainbow trout (Oncorhynchus mykiss) [8] . However, dietary higher soy iso avone showed better growth than without supplemented soy iso avone on juvenile golden pompano (Trachinotus ovatus) [31] and juvenile grass carp (Ctenopharyngodon idella) [11] .…”

“…7 VSI: Viscerosomatic index (%) = 100 × (viscera weight) / (whole-body weight). 8 CF: Condition factor (%) = 100 × (body weight) / (body length) 3 .…”

“…(Table 4). 1 ACP: Acid phosphatase (King's unit/L) 2 AKP: Alkaline phosphatase (King's unit/L) 3 GPT: Glutamic pyruvic transaminase (U/L) 4 GOT: Glutamic oxalacetic transaminase (U/L) 5 CAT: Catalase (U/mL) 6 SOD: Superoxide Dismutase (U/mg prot) 7 T-AOC: Total antioxidant capacity (U/mL) 8 IgM: Immunoglobulin M (g/L) 9 C3: Complement 3 (g/L)…”

“…The process of extruding for soybean is acknowledged to be very useful to remove heat labile ANFs, however, there are thermal stability ANFs in extruded soybean meal has been reported that not only has the negative effect on growth performance, but also damage the intestinal function [6,7] . Soy iso avone are heat-stable glycosides present in soybean meal, also widely known to exert oestrogen like biological effects on animals because of the similarity of their structure to the natural oestrogen structure [8] . There has many physiological function about soy iso avone, especially for immune system regulation [9] , include effects of antioxidant, anti-in ammatory on white shrimp (Litopenaeus vannamei) [10] , and improve the immune response and against Aeromonas hydrophila challenge on juvenile grass carp (Ctenopharyngodon idella) [11] .…”