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    The effects of dietary organic or inorganic selenium in rainbow trout (Oncorhynchus mykiss) under crowding conditions
    (Wiley, 2009) Kucukbay, F. Z.; Yazlak, H.; Karaca, I.; Sahin, N.; Tuzcu, M.; Cakmak, M. N.; Sahin, K.
    In the present study, the effects of different sources of selenium (Se; sodium selenite or selenomethionine) supplementation on the growth and serum concentrations of oxidative stress markers [malondialdehyde (MDA), 8-isoprostane, glutathione peroxidase (GSH-Px) activity] and muscle Se, MDA and heat shock protein 70 (Hsp70) levels in rainbow trouts were evaluated. The fish (n = 360; 0 + years old) with initial average weight of 20 +/- 0.8 g were randomly assigned to 12 treatment groups consisting of 3 replicates of 10 fish each in a 2 x 2 x 3 factorial arrangement of treatments (stocking densities, Se sources, Se levels). The fish were kept at low (25 kg m-3) or high (100 kg m-3) stocking densities and fed a basal (control) diet or the basal diet supplemented with either 0.15 or 0.30 mg of Se kg-1 of diet from two different forms: sodium selenite or selenomethionine. High stocking density decreased weight gain, feed intake and feed conversion ratio (FCR) when basal diet was fed (P = 0.001). A linear increase in feed intake and weight gain and improvement in FCR were found in sodium selenite (P = 0.01)- or selenomethionine (P = 0.001)-supplemented fish reared under crowding conditions. Serum and muscle Se levels and serum GSH-Px activity increased (P = 0.001) linearly, whereas serum and muscle MDA concentrations and serum 8-isoprostane decreased linearly as dietary sodium selenite (P = 0.01) or selenomethionine (P = 0.001) supplementation increased. Selenomethionine and sodium selenite supplementation decreased Hsp70 in the muscle of fish reared under crowding conditions (P < 0.05). Supplementation with Se improved growth and antioxidant status of fish and the effects of selenomethionine were relatively greater than sodium selenite in the crowded groups. Results suggest that crowding conditions cause significant detrimental effects in rainbow trout indicated by increased oxidative stress, reduced feed intake and body weight gain. It also indicates that dietary Se supplementation offers a feasible way of reducing the losses in performance of rainbow trout reared under crowding conditions. Selenomethionine seems to be more effective than sodium selenite and the higer dose in the present study also seems to be more effective than the lower dose.
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    Effects of the supplemental chromium form on performance and oxidative stress in broilers exposed to heat stress
    (Elsevier, 2017) Sahin, N.; Hayirli, A.; Orhan, C.; Tuzcu, M.; Akdemir, F.; Komorowski, J. R.; Sahin, K.
    This experiment was conducted to investigate effects of the organic complex form of supplemental chromium (Cr) on performance, oxidative stress markers, and serum profile in broilers exposed to heat stress (HS). A total of 1,200 10-day-old boilers (Ross-308) was divided into one of the 6 treatments (2 environmental temperatures x 3 diets with different Cr forms). The birds were kept in temperature-controlled rooms at either 22 +/- 2A degrees C 24 h/d (thermoneutral, TN group) or 34 +/- 2A degrees C for 8 h/d, 08:00 to 17:00 h, followed by 22A degrees C for 16 h (HS group) and fed either a basal diet (C) or the basal diet supplemented with Cr (200 mu g/kg) through 1.600 mg of CrPic (12.43% Cr) and 0.788 mg of CrHis (25.22% Cr). Feed intake and body weight were recorded weekly. After cervical dislocation, liver samples were harvested to analyze Cr concentration and glucose transporter-2,4 (GLUT-2,4) expression. The breast meat also was sampled for the concentration of Cr and expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor kappa B (NF-kappa B). Data were analyzed by 2-way ANOVA. Heat stress caused depressions in feed intake (12.1%) and weight gain (21.1%) as well as elevations in feed conversion (11.2%) and abdominal fat (32.8%). It was also associated with depletion of Cr reserves and increases in serum concentrations of glucose, cholesterol, creatine, and enzymes. Exposure to HS was accompanied by suppression of the expressions of Nrf2 and GLUT-2 in muscle and GLUT-4 in the liver and amplification of the expression of NF-kappa B in muscle. Both Cr sources partially alleviated detrimental effects of HS on performance and metabolic profile. The efficacy of Cr as CrHis was more notable than Cr as CrPic, which could be attributed to higher bioavailability. In conclusion, CrHis can be added into the diet of broilers during hot seasons to overcome deteriorations in performance and wellbeing related to oxidative stress.