PROBIOTIC SUPPLEMENTATION AS A STRATEGY FOR IMPROVEMENT IN BODY COMPOSITION, GROWTH, AND SURVIVAL OF PATHOGEN CHALLENGED LABEO ROHITA FINGERLINGS

Abstract

The effectiveness of probiotic-enriched diets on the growth, survival, and body composition of Labeo rohita fingerlings challenged with Pseudomonas fluorescens was assessed in this study. The feed contained two probiotic strains viz Bacillus aerius AsCh-A7 and Sphingomonas sp. AsCh-P3 with antagonistic activity against fish pathogens. All experimental groups and the positive control (C2) received intraperitoneal injections of pathogen suspensions (O.D-0.5), whereas the negative control was fed a sterile diet and was not exposed to any pathogen. Fish were divided into six experimental groups: G2a, G2b, and G2c (for B. aerius AsCh-A7) and G1a, G1b, and G1c (for Sphingomonas sp. AsCh-P3). Probiotic supplementation regimes involved: 30 days feeding after exposure (G1a, G2a); 15 days pre-feeding followed by 30 days after-exposure (G1b, G2b); 15 days pre-exposure feeding (G1c, G2c). Muscle tissue samples were used to assess growth performance and biochemical composition after 45 days. All experimental groups showed improved average weight, weight gain, and specific growth rate (SGR) by both probiotics whereas the pre- and post-treated groups (G1b, G2b) had the highest survival rates (80–90%). The pathogen-exposed control (C2) showed a significant decrease in all biochemical components. With the exception of total protein, ash content, and RNA, Sphingomonas sp. AsCh-P3 supplementation had a substantial impact on the majority of biochemical contents. On the other hand, B. aerius AsCh-A7 supplementation markedly raised total lipids, carbs, RNA, and DNA in all treated groups whereas total protein dropped in G2a and G2b but not in G2c. Sphingomonas sp. AsCh-P3 and Bacillus aerius AsCh-A7 are excellent probiotic candidates for improving the health and resilience of freshwater fish under pathogenic stress.