International Journal of Molecular Veterinary Research, 2025, Vol.15, No.1, 43-50 http://animalscipublisher.com/index.php/ijmvr 47 susceptible strains, with resistant strains being greatly enhanced for survival and decreased pathogen loads (Adamek et al., 2022; Taukhid et al., 2024). In addition, molecular marker-based strategies, such as the utilization of disease-resistance-related microsatellite markers, facilitate non-lethal resistance prediction, diminishing dependence on direct exposure to pathogens (Chen et al., 2021). Figure 2 Resistance map of the Manhattan-resistant tilapia virus (TILV) in breeding populations of Oreochromis niloticus (Adopted from Barría et al., 2021) Image caption: Manhattan plot of GWAS for host resistance, as binary survival, to TiLV. On the y axis is the -log10(P-value). The horizontal dashed red line shows the genome-wide significance threshold. Oni24 represent SNPs with unknown chromosome location (Adopted from Barría et al., 2021) 6.2 Growth performance and adaptability of disease-resistant tilapia strains Disease-resistant tilapia strains are not only selected for resistance but also for growth performance and tolerance to aquaculture conditions. Past experience has proven that disease-resistant varieties of selected disease-resistant tilapia, e.g., improved GIFT tilapia, grow similarly as non-selected ones but experience much lower mortality when the disease hits (Zhu et al., 2024). For instance, two cycles of selection led to disease-resistant GIFT tilapia with mortality levels of about 1% compared to 10% for the control without any observed loss in growth performance. This indicates that disease resistance can be achieved without productivity loss. 6.3 Case studies of disease-resistant tilapia applications in aquaculture practice and industry Practical application of disease-resistant GIFT strains has been reported in different regions of the world. Microsatellite marker-assisted selection for developing enhanced survival against Streptococcus infection in tilapia lines has encouraged acceptance in industry in Taiwan (Chen et al., 2021). The GIFT strain has been widely spread in China, as genomic selection and challenge testing has validated its increased resistance against S. agalactiae and TiLV, with lower losses and increased aquaculture returns (Barría et al., 2021). As with red tilapia breeding in Egypt, which focused on developing disease resistance, this highlights the applicability and long-term viability of genetic interventions in disease control in commercial aquaculture. Case studies are evidence of the success of genetic and phenotypic test applications in advancing and industry uptake of disease-resistant tilapia. 7 Integrating Disease-Resistant Breeding and Aquaculture Management 7.1 Synergistic effects of disease-resistant strains and optimized farming environments The integration of resistant tilapia stocks to better aquaculture environments optimizes overall fish health and production. Resistance selection optimizes survival and robustness of populations but are optimized when supplemented with optimal water quality, good nutrition, and good farm management. Precision farming systems, for example, real-time monitoring, and enhanced husbandry practices optimize the health and productivity of resistant stocks. This combined approach not only reduces disease occurrence but also enhances growth rates and resource utilization efficiencies to result in better aquaculture farms' health and climate resilience (Nguyen, 2024). 7.2 Role of disease prevention and biosecurity measures in resistant strain development Biosecurity and disease management are required complements to genetic enhancement. Good biosecurity by pathogen exclusion, regular health checks, and vaccination remains essential even in the case of disease-resistant
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