Productivity, activity of digestive and antioxidant enzymes of carp (Cyprinus carpio Linnaeus, 1758) as a result of the use of inulin in low-nutrient feeds

Abstract

Purpose. To evaluate the effect and outline the prospects for adding inulin to the low-nutrient diet of carp in accordance with productive parameters, activity of digestive tract enzymes and the antioxidant defense system. Methodology. Experimental feeding of carp was carried out for 20 days at the laboratory complex of the fish farm «Karpatskyi Vodogray» LLC, Pustomyty, Lviv region. A control and two experimental groups of fish were created, which were kept in identical optimal conditions. Two 200 dm3 tanks were used, each of which contained 20 age-1+ carps with an average initial weight of 64.5 g. Carps of the control group (Control) were fed with a feed mixture with a protein content of 15%. Feed inulin in the amount of 0.2 (Experiment 1) and 0.4% (Experiment 2) was added to the feed of the experimental groups of fish. At the end of the experimental feeding, the selected fish were analyzed for productive parameters, antioxidant and digestive enzyme activity using methods generally accepted in aquaculture. Findings. The studies showed higher values of morphometric parameters of carps in the experimental groups compared to the control group, which is consistent with productive parameters. The average weight after rearing in Experiment 1 was 14.44% higher than in the control, in Experiment 2 – by 3.84%. The condition factor in the control group was 2.90, in the experimental 2.92 and 2.64, respectively. The relative weight gain of fish in the control group was 6.58%, and it was higher in the experimental group – 9.69 and 7.16%. A tendency to increase the activity of the enzyme link of the antioxidant defense system of superoxide dismutase by 6.06 (Experiment 1) and 7.13% (Experiment 2) was detected in the liver. At the same time, lower levels of lipid peroxidation products were found: diene conjugates – by 11.46 and 50.70%; TBA-active products – by 3.85 and 16.55%, respectively, that may indicate a decrease in oxidative stress. The addition of the prebiotic supplement to the diet of age-1+ carp did not cause pathological processes in the functioning of intestinal tract enzymes. An increase in the activity of alkaline phosphatase by 3.03% in Experiment 1 and twice (p < 0.01) in Experiment 2 relative to the control, as well as a slight decrease in the activity of α-amylase, was found, which may indicate adaptation to the new diet. Originality. Based on a comprehensive ana­lysis of the productive parameters and functional state of the carp body, the prospects for the use of the prebiotic inulin in low-nutrient feeds were investigated for the first time. Practical Value. The study is aimed at obtaining results to determine the effectiveness of the use of inulin in carp feeding as part of low-nutrient feeds. The practical use of the knowledge gained outlines the possibility of optimizing the production of fish when introducing resource-saving technologies in aquaculture.

Keywords

• carp
• feed additives
• prebiotic
• productive parameters
• functional state of the body
• resource-saving technologies in aquaculture