Evaluating Non-Antibiotic Therapeutic Strategies for Controlling Lactococcosis in Nile Tilapia: Investigating the Efficacy of Aloe Vera Extracts, Vitamin D and Selenium Supplement, and Probiotics in Experimental Infections

This study investigated non-antibiotic therapeutic strategies for controlling lactococcosis in Nile tilapia (Oreochromis niloticus). The efficacy of Aloe vera extract, Vitamin E/Selenium supplementation, and multi-strain probiotics was evaluated against Lactococcus garvieae infection in an experimental setting. Two hundred Nile tilapia were divided into four groups: control, Aloe vera, Vitamin E/Selenium, and probiotic. After a 42-day treatment period, fish were challenged with L. garvieae and monitored for 28 days. Clinical signs, mortality rates, and survival were assessed. The control group exhibited severe disease progression with 100% mortality by day 21 post-infection. Aloe vera treatment reduced mortality to 20%, showing moderate efficacy. Vitamin E/Selenium supplementation provided greater protection with only 5% mortality. The probiotic-treated group demonstrated the most remarkable results, with no clinical signs or mortalities throughout the study. Statistical analysis revealed significant differences between treatment groups and the control, with probiotics showing the largest effect size (Cohen's d = 0.98, p < 0.001), followed by Vitamin E/Selenium (Cohen's d = 0.9, p = 0.001) and Aloe vera (Cohen's d = 0.74, p = 0.003). These findings highlight the potential of non-antibiotic interventions in managing L. garvieae infections, with probiotics emerging as the most effective treatment. The study contributes to the development of sustainable aquaculture practices and reduced reliance on antibiotics, aligning with global efforts to mitigate antimicrobial resistance in aquaculture.