Functional benefits of soy lecithin supplementation in feeds for channel catfish (Ictalurus punctatus) juveniles: Impacts on production performance, intestinal health, and disease resistance

Soy lecithin (SL), a phospholipid-rich by-product of soybean oil (SBO), has been commonly supplemented aquafeeds. This study evaluated SL as a feed additive to enhance growth, stress resilience, and disease resistance in juvenile channel catfish ( Ictalurus punctatus ). In Trial 1, feeds were formulated with plant-based ingredients, with SL included at 0, 0.5, 1.0, 1.5, and 2.0%, replacing SBO. Catfish fed diets with 1.5% SL had greater feed efficiency, while those supplemented with 0.5% SL had greater protein conversion efficiency. Following an acute air exposure challenge, stress markers increased from 0 to 2 h, then decreased by 6 h. Survival after the bacterial challenge increased with graded inclusion of SL. In Trial 2, three diets were tested: control (SBO), 1% SL, and catfish oil (CFO). Fish fed the SL diet had greater feed efficiency than those fed the SBO diet. However, there were no differences between treatments in terms of survival, condition indices, intestinal microbiota, or blood parameters, except for hemoglobin, which was greater in the CFO group compared to the SBO group. Gene expression of tnf-α was significantly higher for fish fed diets supplemented with SL, while no differences were observed for other cytokines. Fish fed SL exhibited greater survival when compared to the SBO group after bacterial challenge. In conclusion, data obtained suggest SL supplementation can improve channel catfish growth performance and disease resistance, with survival after the bacterial challenge responding in a dose-dependent manner. • Dietary soy lecithin supplementation improved feed efficiency. • Higher expression of TNF-α in the intestine of fish fed soy lecithin. • The addition of soy lecithin did not affect the intestinal microbiota. • Soy lecithin supplementation improved survival after bacterial challenge.