Nutrient Digestibility and Growth Performance of Juvenile Penaeus vannamei Fed Diets Containing the Filamentous Fungus, Paecilomyces variotii, Produced From Corn Ethanol Thin Stillage.

Fungal proteins are emerging ingredients having high potential for use in aquafeeds, yet digestibility and practical inclusion limits remain unclear for marine shrimp. This study evaluated a filamentous fungus (Paecilomyces variotii [PV]) produced from corn ethanol thin stillage as a replacement for salmon by-product meal (SLM) and poultry by-product meal (PBM) in diets for juvenile Penaeus vannamei. Five diets were formulated by replacing SLM and PBM with PV (0%-100% replacement; PV from 0% to 22.60% of the diet). After 78 days, shrimp performance was similar across treatments. Survival remained high (95.6 ± 3.4%). Weekly growth averaged 1.04 ± 0.08 g/week, with a gained yield of 1168 ± 92 g/m2. Apparent feed intake (AFI) was 14.6 ± 0.6 g/shrimp, and feed conversion ratio (FCR) was 1.33 ± 0.09. Final body weight (BW) differed statistically among dietary treatments, with shrimp fed the diet containing 22.60% PV exhibiting a reduction (12.31 ± 1.89 g) compared with 0% PV (12.80 ± 2.02 g). In a digestibility assay (substitution method; 30% test ingredient), ingredient-level crude protein (CP) apparent digestibility coefficient (ADC) was higher for SLM (72.02 ± 1.96%) than for the PV (62.28 ± 0.48%). Amino acid (AA) digestibility was consistently lower for PV, with marked reductions in methionine (Met) (73.21 ± 1.72% vs. 85.71 ± 1.05%) and lysine (Lys) (86.23 ± 0.66% vs. 89.35 ± 1.10%) compared with SLM. Whole-body proximate composition at harvest was largely unaffected by dietary treatment, whereas nutrient and energy retention differed, with the highest protein retention observed at 75% replacement and reduced lipid and energy retention at 100% replacement. Overall, results indicated that PV can replace up to 75% of SLM and PBM, corresponding to 16.95% dietary inclusion, in diets for P. vannamei without impairing growth performance, whereas complete replacement (22.60% PV) reduces nutrient utilization efficiency and final BW.