Blend de prebiótico, probiótico e ácidos orgânicos em dietas para tilápia-do-nilo

Abstract

The aquaculture in Mato Grosso of South is growing, for this reason, there has been a significant increase in research into alternative foods and food additives that improve the utilization of the nutrients ingested in the diet, allowing animals to perform better in zootechnical terms, as well as helping the immune system, with a higher survival rate. The use of a blend of organic acids increases and enhances antimicrobial activity, and consequently has positive effects on zootechnical performance and nutrient utilization by the animals. The use of a blend of probiotics and prebiotics prevents the loss of bacterial diversity in the gut and its mechanism of action prevents pathogenic bacteria from colonizing the fish gut. The aim of this study was to verify the dietary influence of a blend composed of prebiotics, probiotics and organic acids in Nile tilapia diets in the fry (experiment 1) and juvenile (experiment 2) stages, on zootechnical performance, digestive and liver enzymes, liver, intestine and muscle histology, bromatological composition and blood biochemical analyses (only for juveniles). Experiment 1: 160 animals with an initial weight of 2,22±0,06 grams were used, distributed in a completely randomized design, consisting of five treatments and four replications, totaling 20 experimental units (80 L water tanks), over a period of 31 days. The animals were fed four times a day (08:00, 11:00, 14:00 and 17:00 hours) until apparent satiety. A commercial ration with 46% crude protein was purchased, and a mixture of additives was added to the ration by means of an oil bath (2%), at the following dosages Control T1 (0,0 g kg-1), T2 (2,5 g kg-1), T3 (5,0 g kg-1) T4 (7,5 g kg-1) and T5 (10,0 g kg-1). After the experimental period, evaluations of performance variables, bromatological composition, enzymes and histology were carried out. The inclusion of additives in the diet of juvenile tilapia had no effect on zootechnical performance parameters (weight gain; feed conversion, specific growth rate, hepatosomatic index, visceral fat index and intestinal quotient (p>0.05). The inclusion of additives had a significant effect on the bromatological parameters moisture, protein and mineral matter (p<0.05). There were also significant differences (p<0.05) for the digestive enzymes protease, lipase and alkaline phosphatase, and for the liver enzymes SOD and CAT. The inclusion of additives had no effect on the diameter of hepatocyte, nuclei and hepatocyte area, but there was a significant effect on the area of hepatocyte nuclei. In the histology of the intestine, there was no significant effect on the height, width and area of the villi, nor was there any significant effect on the frequency of distribution of muscle fibers in the histology of the muscle of Nile tilapia fry. The inclusion of the blend of prebiotics, probiotics and organic acids resulted in changes in the activity of digestive enzymes and antioxidants, proving that its use has beneficial effects for the animal. Experiment 2: 150 animals with an average initial weight of 44,89 ± 0,82 g and an average initial length of 12,88±0,12 cm were used, distributed in a completely randomized design in 15 water tanks (2000 L), with three replicates per treatment, over a period of 30 days. The fish were fed a commercial diet with 35% crude protein and additives added by means of an oil bath (2%). The treatments consisted of the inclusion of a blend of additives made up of prebiotics, probiotics and organic acids, which were included in the feed and were determined as: Control T1 (0,0 g kg-1), T2 (2,5 g kg-1), T3 (5,0 g kg-1) T4 (7,5 g kg-1) and T5 (10,0 g kg-1). The inclusion of additives had no significant effect on performance parameters, initial weight, final weight, weight gain, final biomass, biomass gain, final length, feed consumption, feed conversion, daily weight gain, specific growth rate, visceral fat index, hepatosomatic index, intestinal quotient and survival (p >0.05). There were significant differences (p<0.05) for the enzymes lipase, alkaline phosphatase, ALT and SOD. In the biochemical analysis of the blood, significant differences were found for cholesterol, triglycerides, proteins, albumin, globulin and creatinine. The inclusion of the blend had no effect on hepatocyte diameter, hepatocyte nucleus diameter, hepatocyte area and hepatocyte nucleus area. In the histology of the intestine, there was no significant effect on the height, width and area of the villi, nor was there any significant effect on the frequency of distribution of muscle fibers in the histology of the muscle. The inclusion of 10 g kg-1 of the blend was the dose that gave the animals the best results in terms of the activity of the enzymes lipase, alkaline phosphatase CAT and SOD.