ISSUE FOCUS 34 FEED & ADDITIVE MAGAZINE August 2025 crucial under heat stress conditions. Alltech’s mannan-rich fraction (MRF), a refined form of mannan oligosaccharides from a select strain of Saccharomyces cerevisiae, has been widely investigated as a functional additive in diets of aquaculture species. Alltech’s MRF, when supplemented in diets of the gilthead seabream during thermal stress (34°C), enhanced the immune health status of the animal (Figure 3), as shown by higher lysozyme content, lower levels of cortisol, and expression levels of il-1β, ghr-1, igf-1 and tnf-α in the gut compared to the control (Khosravi‐Katuli et al., 2021). Ultimately, global warming poses multifaceted challenges to aquaculture, affecting marine and freshwater environments, multiple regions and diverse species. These changes necessitate adaptive nutritional strategies to ensure the sustainability and resilience of aquaculture practices in a changing climate. References are available upon request. About Dr. Vivi Koletsi As a Global Technical Support Specialist within Alltech’s Technology Group, Dr. Vivi Koletsie collaborates with the company’s global aqua team regarding all technologies on the aquatic species side. Dr. Koletsi, a native of Ioannina, Greece, first became interested in aquaculture while completing her undergraduate studies in biology at the Aristotle University of Thessaloniki. She began focusing on fish nutrition in earnest while pursuing her master’s degree in aquaculture and marine resource management at Wageningen University & Research in the Netherlands. This interest led her to complete an internship with Alltech Coppens, during which she established a protocol to help prevent mycotoxin contamination in aqua feeds. Upon earning her master’s degree, Dr. Koletsi continued her mycotoxin research at the doctoral level with support from Alltech in collaboration with the Aquaculture and Fisheries Group at Wageningen University & Research. While completing her doctoral studies, Dr. Koletsi conducted trials at Alltech Coppens’ facilities while continuing laboratory work at Wageningen. Her focus was on mycotoxins’ impact on rainbow trout. Dr. Koletsi joined Alltech as a team member upon completion of her Ph.D. in 2023. Control Seabream 50 45 40 35 30 25 20 15 10 5 0 Cortisol (mg/dl) Lysozyme (ng/l) Relative il-1β gene expression Relative ghr-1 gene expression Relative igf-1 gene expression Relative tnf-α gene expression b a a a a c c b b b b b 900 800 700 600 500 400 300 200 100 0 8 7 6 5 4 3 2 1 0 3 2.5 2 1.5 1 0.5 0 3.5 3 2.5 2 1.5 1 0.5 0 4 3.5 3 2.5 2 1.5 1 0.5 0 MRF Control MRF Control MRF Control MRF Control MRF Control MRF Figure 3. Plasma cortisol and serum lysozyme levels, relative gene expression of il-1β, tnf-α ghr-1, igf-1 in intestine of seabream fed a control and MRF-supplemented diet after 10 days of heat stress at 34°C (Khosravi‐Katuli et al., 2021)
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