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The effect of dietary inclusion of soy protein concentrate (SPC) and simultaneous supplementation with taurine on the growth, hematology, blood biochemistry, and liver histology of totoaba (Totoaba macdonaldi) juveniles was assessed. Four isoproteic and isolipidic diets were formulated containing either 30 or 60% of SPC (diets S30 and S60), supplemented or not with 1% of taurine (diets S30T and S60T). A fishmeal-based diet formulated for totoaba nutritional requirements, without SPC and taurine supplementation, was used as a reference diet. Triplicate groups of 32 totoaba juveniles (average body weight 7.5 ± 0.6 g) were fed these diets for 45 days. Results showed that growth performance in fish fed S30, S30T, and S60T was similar to fish fed the reference diet. Red blood cells and hematocrit in fish fed with supplemented taurine in both levels of SPC (S30T and S60T) were similar to the fish fed the RD; the addition of taurine improved the state of hydration of totoaba. Plasmatic hemoglobin in fish fed the lower SPC level was similar to fish fed the RD. The mean corpuscular hemoglobin concentration in fish fed S30T was similar to fish fed the RD, taurine supplementation prevented the development of hypochromic anemia in this group of fish. Plasmatic albumin in fish fed S30 was similar to fish fed the RD. Plasmatic total protein and globulin concentration increased and AL:GLB (albumin:globulin ratio) decreased in fish fed the SPC-based diets despite taurine supplementation. The protein profile showed that taurine supplementation did not prevent a possible inflammatory process (increased globulins, decreased AL:GLB) in juvenile totoaba fed both levels of SPC. Glucose concentration was similar in fish fed S30, S30T, and S60T. The histological hepatic index was highest in fish fed S60. These results suggest that with an appropriate nutritional level, taurine may play an important modulatory role in the hematology and blood biochemistry status in totoaba fed SPC-based diets, contributing to the enhancement of an overall healthy growth performance.

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