The effect of various additives on the level of antibacterial protection of juvenile sterlet

An important task for the successful development of aquaculture is to increase the resistance of fish to infections in the early stages of ontogenesis, when the immune system has not yet formed. The main protective function is performed by physical barriers: cuticle and mucous membrane, which include antimicrobial peptides and immunoglobulins. The main role in neutralizing harmful microflora is played by the enzyme lysozyme, which has bacteriolytic activity. The purpose of the study is to study the effect of various drugs on the level of antibacterial protection of young sterlet. The study was conducted for 27 days on young sterlet. The fish were divided into 7 groups: control and 6 experimental, receiving various drugs ("Antibak-100", "Sub-Pro", "Ecoflor", "Aquatan", "Roncoleukin" and "Polyphepan"). The drugs were added to the feed according to the instructions. Samples for bacterial contamination analysis were collected on the 7th, 14th, 21st and 27th days. Four individuals from each group were selected for the study. Water was removed from the fish using filter paper and an imprint was made on a solid medium (nutrient fish-peptone agar) in an individual sector. Petri dishes were placed in a thermostat at 26°C for 1 day. Then the number of bacterial colonies in each sector was visually counted. During the study, fluctuations in bacterial contamination were recorded in all the studied groups. The maximum decrease in bacterial contamination was observed on the 14th – 21st days. The lowest number of bacterial colonies on the body of young sterlet was found in the groups receiving the probiotic "Sub-Pro" and the immunomodulator "Roncoleukin". An increase in bacterial contamination was recorded at the end of the experiment. In the last 2 weeks of the experiment, a significantly lower number of colonies was found in all experimental groups compared to the control. The data obtained indicate different duration and effectiveness of the antibacterial action of the drugs used.

1. Magnadottir, B. Innate immunity of fish (overview) / B. Magnadottir // Fish Shellfish Immunol.2006:20;2:137-151. DOI: 10.1016/ j.fsi.2004.09.006.

2. Pietrzak, E. Innate Immune Responses of Skin Mucosa in Common Carp (Cyprinus Carpio) Fed a Diet Supplemented with Galactooligosaccharides / E. Pietrzak, J. Mazurkiewicz, A. Slawinska // Animals (Basel).2020:10;3:438. DOI: 10.3390/ ani10030438.

3. Zhang, Y. A. IgT, a primitive immunoglobulin class specialized in mucosal immunity / Y. A. Zhang, I. Salinas, J. Li, D. Parra, S. Bjork, Z. Xu, S. E. LaPatra, J. Bartholomew, J.O. Sunyer // Nat Immunol.2010:11;9:827-835. DOI: 10.1038/ ni.1913.

4. Parfenova, S. R. Lysozyme activity of fish mucus / S. R. Parfenova // StudNet.2020:12:1034-1040. URL:https://cyberleninka.ru/article/n/lizotsimnayaaktivnost-slizi-ryb (In Russ.)

5. Subramanian, S. Comparison of antimicrobial activity in the epidermal mucus extracts of fish / S. Subramanian, N. W. Ross, S. L. MacKinnon // Comp Biochem Physiol B Biochem Mol Biol.2008:150;1:85-92. DOI: 10.1016/j.cbpb.2008.01.011.

6. Poloz, S. V. Evaluation of fish resistance to parasite infestation under stress and determination of resistance indicators (experimental study) / S. V. Poloz, S. M. Degtyaryk, G. V. Slobodnitskaya, I. I. Strelchenya // Ecology and Animal World.2024:1:28-33. URL: https://animal.belal.by/jour/article/view/153 (In Russ.)

7. Irkitova, A. N. Optimization of the method for determining the antagonistic activity of probiotic bacteria / A. N. Irkitova, E. S. Yatsenko // Technologies of the food and processing industry of the agro-industrial complex - healthy food products.2017:5;19:113-117. URL: https://www.elibrary.ru/item.asp?id=32607459 (In Russ.)

8. Yukhimenko, L. N. Therapeutic and preventive measures against bacterial diseases in fish farming / L. N. Yukhimenko, S. B. Tokareva, M. S. Kukin, L. I. Bychkova // Veterinary medicine and feeding.2021:6:67- 69. DOI: 10.30917/ATT-VK-1814-9588-2021-6-18. URL: https://www.elibrary.ru/item.asp?id=47419316 (In Russ.)

9. Zekov, D. D. Determination of effective rates of introduction of the feed additive Aquatan into the diet of rainbow trout with a biological assessment of the effect on fishery indicators / D. D. Zekov, M. V. Ulyanov, D. V. Mikryakov, T. A. Suvorova // Fish farming and fish farming.2021:11:66- 77. DOI: 10.33920/sel09211106. URL: https://www.elibrary.ru/item.asp?id=47327779 (In Russ.)

10. Use of ellagitannins in aquaculture diets. 2020. URL: https://apknews.su/ article/213/2594/ (date of access 12.05.2025).

11. Tkachenko, H. The antibacterial activity of the ethanolic leaf extract of Ficus pumila l. (moraceae) against fish bacterial pathogens / H. Tkachenko, L. Buyun, O. Kasiyan, E. Terech-Majewska, Z. Osadowski // Scientific works of Dalrybvtuz.2018:45;2:20-30. URL: https://elibrary.ru/item.asp?id=35176457

12. Mohammadian, T. Administrations of autochthonous probiotics altered juvenile rainbow trout Oncorhynchus mykiss health status, growth performance and resistance to Lactococcus garvieae, an experimental infection / T. Mohammadian, M. Nasirpour, M. R. Tabandeh, A. A. Heidary, R. GhaneiMotlagh, S. S. Hosseini // Fish Shellfish Immunol.2019:86:269-279. DOI: 10.1016/j.fsi.2018.11.052.

13. Bychkova, L. I. Probiotic drug SUBPRO (subalin) - an alternative to antibiotics / L. I. Bychkova, L. N. Yukhimenko, A. G. Khodak, O. S. Skorobogatko // Fish farming.2008:2:48-49. URL: https://elibrary.ru/ author items.asp?authorid=1028699&pubrole=100&show refs=1&show option=0 (In Russ.)

14. Degtyarik, S. M. Study of plant extracts for pathogens of aeromonosis and pseudomonosis in fish / S. M. Degtyarik, E. I. Grebneva, G. V. Slobodnitskaya, N. A. Benetskaya, E. V. Maksimyuk, A. V. Bespaly // Issues of fisheries of Belarus.2016:32:249-261. URL: https://www.elibrary.ru/item.asp?id=28114134 (In Russ.)

15. Biller-Takahashi, J. D. Fish Immunology. The modification and manipulation of the innate immune system: Brazilian studies / J. D. Biller-Takahashi, E. C. Urbinati // An Acad Bras Cienc.2014:86;3:1484-506. DOI: 10.1590/0001-3765201420130159.

16. Immanuel, G. Dietary medicinal plant extracts improve growth, immune activity and survival of tilapia Oreochromis mossambicus / G. Immanuel, R. P. Uma, P. Iyapparaj, T. Citarasu, S. M. Punitha Peter, M. Michael Babu, A. Palavesam // J. Fish Biol.2009:74;7:1462-1475. DOI: 10.1111/j.1095-8649.2009.02212.x.

17. Nya, E. J The garlic component, allicin, prevents disease caused by Aeromonas hydrophila in rainbow trout, Oncorhynchus mykiss (Walbaum) / E. J Nya, Z. Dawood, B. Austin // J Fish Dis.2010:33;4:293-300. DOI: 10.1111/j.1365-2761.2009.01121.x.

18. Nechaeva, T. A. Efficiency of using recombinant interleukin-2 (Roncoleukin) in trout farming / T. A. Nechaeva, M. V. Ostrovsky // International Bulletin of Veterinary Science.2009:3:43-49. URL: https://elibrary.ru/llzgzv (In Russ.)

19. Zueva, M. S. Modern experience of including biologically active feed additives in the diet of fish / M. S. Zueva // Animal husbandry and forage production.2022:105;4:146-164. URL: http://gk.fncbst.ru/arhiv/new/vypuski-2022-goda/tom-105-№-4/teoriya-i-praktika-kormleniya/zueva-m-s (In Russ.)

20. Mehrabi, Z. Immunity and growth improvement of rainbow trout (Oncorhynchus mykiss) fed dietary nettle (Urtica dioica) against experimental challenge with Saprolegnia parasitica / Z. Mehrabi, F. Firouzbakhsh, G. Rahimi-Mianji, H. Paknejad // Fish Shellfish Immunol.2020:104:74 -82. DOI: 10.1016/j.fsi.2020.05.050.

21. Bulfon, C. Resistant and susceptible rainbow trout (Oncorhynchus mykiss) lines show distinctive immune response to Lactococcus garvieae / C. Bulfon, M. Prearo, D. Volpatti, O. Byadgi, M. Righetti, M. G. Maniaci, V. Campia, P. Pastorino, F. Pascoli, A. Toffan, C. Biolatti, P. L. Acutis, S. Colussi // Fish Shellfish Immunol.2020:105:457-468. DOI: 10.1016/j.fsi.2020.06.040.

22. Jinendiran, S. Modulation of innate immunity, expression of cytokine genes and disease resistance against Aeromonas hydrophila infection in goldfish (Carassius auratus) by dietary supplementation with Exiguobacterium acetylicum S01 / S. Jinendiran, A. A. Nathan, D. Ramesh, B. Vaseeharan, N. Sivakumar // Fish Shellfish Immunol.2019:84:458-469. DOI: 10.1016/j.fsi.2018.10.026.

23. Bu, X. Dietary yeast culture modulates immune response related to TLR2-MyD88- NF-kβ signaling pathway, antioxidant capability and disease resistance against Aeromonas hydrophila for Ussuri catfish (Pseudobagrus ussuriensis) / X. Bu, X. Lian, Y. Wang, C. Luo, S. Tao, Y. Liao, J. Yang, A. Chen, Y. Yang // Fish Shellfish Immunol.2019:84:711-718. DOI: 10.1016/j.fsi.2018.10.049.

24. Kar, B. Variation in susceptibility pattern of fish to Argulus siamensis: Do immune responses of host play a role? / B. Kar, C. Moussa, A. Mohapatra, J. Mohanty, P. Jayasankar, P. K. Sahoo // Vet Parasitol.2016:221:76-83. DOI: 10.1016/j.vetpar.2016.03.013.