Dietary inclusion of agricultural by-products, algae, and probiotics in a dry feed: Effects on growth performance, survival, immune response, biochemical indices, and reproductive traits of Artemia parthenogenetica

The cultivation of Artemia , a vital live food for fish and shellfish larvae, is hindered by the inconsistent supply and high costs of fresh microalgae, limiting sustainable larviculture in aquaculture. The cultivation of Artemia , a vital live food for fish and shellfish larvae, is hindered by the inconsistent supply and high costs of fresh microalgae, limiting sustainable larviculture in aquaculture. To address these challenges related to high microalgal feed costs and supply inconsistency, we developed and tested formulated dry feeds incorporating agricultural by-products (rice bran, wheat bran, soybean meal), varying levels of algae (5 % or 10 %), and probiotic bacteria ( Bacillus coagulans and Bacillus subtilis at 0 %, 0.6 %, or 1.2 %) against a control diet (25 % algae + 75 % yeast). Artemia parthenogenetica cysts were hatched under standard conditions, and nauplii were reared for 23 days in three replicates per treatment (n = 3) to evaluate growth, survival, biochemical composition, reproductive characteristics, digestive and oxidative stress enzymes, and resistance to Vibrio anguillarum . Reproductive assessments continued up to 73 days until all female Artemia are dead. The optimized formulation (10 % algae + 1.25 % probiotics) significantly improved Artemia nauplii growth (body length +15.8 %), survival (+12.5 %), and digestive protease activity (21 % higher alkaline protease) compared to the control. Notably, antioxidant enzyme activities—superoxide dismutase (SOD) and glutathione peroxidase (GPx)—declined progressively in control-fed Artemia with extended culture duration; however, probiotic supplementation substantially attenuated this decline, indicating sustained antioxidant capacity. During pathogen challenge with Vibrio anguillarum , probiotic-supplemented Artemia exhibited superior survival across all life stages (nauplii: 92.24 % vs. 41.99 % in controls; adults: 70.09 % vs. 45.22 %), which was mechanistically linked to enhanced innate immune responses, including elevated alkaline protease activity and reduced oxidative stress biomarkers. • A dry diet with 10 % microalgae and 1.25 % probiotics (T6) markedly boosts +15.8 % length, +12.5 % survival, and 3.5× offspring. • Adding probiotics to the diet increases alkaline protease +21 %, prolongs reproduction to 46 days, and lifespan to 73 days. • Optimized T6 diet confers strong Vibrio protection (92.24 % survival) and lowers oxidative stress.