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-The study evaluated the replacement of bovine heart by gelatin in the feed training of carnivorous fish, using giant trahira (Hoplias lacerdae) as an experimental model. A completely randomized design with four treatments and five repetitions was employed. The treatments were composed of wet ingredients beef heart (control), gelatin diluted in water, gelatin diluted in beef heart broth, and gelatin diluted in water mixed with fish meal. The fish (3.22±0.03 cm and 0.57±0.01 g) were conditioned to accept industrialized diets by the technique of gradual feed ingredients transition in the diet. Gains in weight and length, efficiency of feed training, specific growth rate, cannibalism, mortality and survival rates were evaluated. There was significant difference in weight and length gains and specific growth rate, whereby the use of bovine heart gave the best results. Greater efficiency of feed training was observed for fish fed diets containing beef heart and gelatin diluted in water mixed with fish meal. The high survival rates and the absence of significant differences among treatments for rates of cannibalism, mortality and survival indicate the feasibility of using gelatin as a moist ingredient in the feed training of carnivorous fish.

This study aimed to evaluate the effect of different levels of conjugated linoleic acid (CLA) on growth performance, carcass chemical composition and fatty acid profile of lambari (Astyanax altiparanae). A completely randomized experimental design with six treatments, diets with graded levels of CLA (0.0, 5.0, 10.0, 15.0, 20.0 and 25.0 g kg À1 ) and five repetitions. Fish (n = 570; weight: 1.58 AE 0.23 g) were distributed into 30 (70-L) aquaria and fed the experimental diets during 90 days. No effects of dietary supplementation with CLA on fish performance and carcass chemical composition were observed. CLA influenced carcass fatty acid profile, a positive relationship was found for 16:1 n-9, 18:1 n-9, 18:2(cis-9, trans-11), 18:2(trans-10, cis-12) and 20:1 n-9, and a negative relationship was found for 15:1 n-7, 16:0, 16:1 n-5, 18:2 n-6, 18:3 n-3, 20:5 n-3 and 22:4 n-6. Total CLA and monounsaturated fatty acids (MUFA) linearly increased with the increase in dietary CLA, while saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) of n-6 and n-3 series linearly decreased. Dietary CLA can be incorporated into the lambari (A. altiparanae) muscle, and the fish can be used as functional foods, because CLA is related to the prevention of various diseases in humans.

Two trials were conducted to evaluate the effects of soybean meal replacement by corn distiller’s dried grains with soluble (DDGS) in diets for pacu juveniles. Five diets were formulated with 0, 100, 200, 300, and 400 g of DDGS/kg diet replacing up to total dietary soybean meal. In trial 1, the experimental diets were fed to five groups of fish to evaluate the apparent digestibility coefficients (ADC). In trial 2, four groups of fish were fed each experimental diet for 100 days to evaluate the effects of these diets on digestive enzymes activity, intestine oxidative stress, and intestine morphology. The ADCs of dry matter and energy was reduced with dietary DDGS inclusion, while the ADC of lipids was increased, and no differences were observed for the ADC of protein. Independently of dietary treatment, pH increased from anterior to the distal intestine with dietary DDGS inclusion. Digestive enzymes’ activities were higher on anterior than the distal intestine. Dietary DDGS decreased lipase, amylase, chymotrypsin, and trypsin activities, while no differences were observed for total proteases activity. Intestine glucose-6-phosphate dehydrogenase was reduced in fish fed the DDGS diets while catalase activity increased. Lipid peroxidation was lower in fish fed DDGS diets than the control. Intestine histomorphology improved with dietary DDGS inclusion. Overall, soybean meal negative effects could be decreased by dietary replacement with corn DDGS which may have a prebiotic effect, improving intestine health.