Efeito dos ácidos graxos da série n3 e n6 no reparo de lesões cutâneas em Oreochromis niloticus

Abstract

In the intensive production system, fish are more susceptible to various injuries and these serve as an entry point for pathogens, causing economic loss. Extremely important to reduce negative impacts, tissue repair must be fast and effective for the return to homeostasis. The supply of polyunsaturated fatty acids can modulate the wound repair process in many species. In this context, the objective was to evaluate the effect of supplementation of different sources of fatty acids on performance, chemical composition, biochemical parameters and on the regeneration of skin lesions in Oreochromis niloticus. 144 fish were used, housed in 36 aquariums 16L, in a completely randomized design. The animals were fed twice a day with three experimental diets, varying only the lipid sources (fish oil, corn oil and flaxseed oil). Wound induction was performed 30 days after feeding the diets, using a 5mm Punch scalpel. Samples were collected 12 hours, 1 day, 7 days and 14 days after injury. Biometric and feed intake data were used to calculate performance parameters. The following zootechnical indices were evaluated: hepatosomatic (IHS), viscerosomatic (IVS), intestine somatic (IIS) and visceral fat (IGVS). The lipid profile of diet and fish was analyzed by gas chromatography. The proximate composition of diets and fish was performed. Blood was collected to assess plasma protein, hematocrit, glucose, total erythrocyte count and leukocyte differential. Cranial kidney, spleen and plasma samples were used for analysis of interleukins 1β, 6 and 10 (IL-1β, IL-6, IL-10), tumor necrosis factor α (TNF-α) and cyclooxygenase 2 (COX-2), by enzyme-linked immunosorbent assay. The tissue repair process was followed by histopathological analysis and through the imaging software, AxioVision. Data were evaluated by Two-Way ANOVA (p<0.05). No significant differences were observed in weight gain, feed conversion, IHS, IVS, IIS, IGVS and in the proximate composition of fish for the variables, dry matter, crude protein and ash. Overall, muscle fatty acids reflected the fatty acid composition of the diet. The corn oil group had a higher blood concentration of neutrophils after 12 hours and 7 days. The groups supplemented with fish oil and flaxseed had a smaller wound area on the 7th day after injury induction, with a reduction of 69% and 56%, compared to corn oil. Histopathological analysis revealed enhancement of epidermis and dermis repair, stimulation of fibroblast and collagen synthesis, and immunomodulation of cytokines and inflammatory cells in treatments with fish oil and flaxseed. Based on the results obtained, it is suggested that the n3 series fatty acids accelerate the process of regeneration of lesions in Oreochromis niloticus.