Replacement of Wheat With Barley With or Without Exogenous Carbohydrases in Pacific White Shrimp ( Litopenaeus vannamei ): Effects on Growth, Digestibility, and Gene Expression

Barley can potentially replace wheat in aquaculture feed. However, barley contains relatively higher fiber and β‐glucans levels, which may reduce digesta viscosity, and hinder endogenous enzyme activities. Supplementation of exogenous enzymes in barley‐based diets could aid in hydrolyzing the non‐starch polysaccharides (NSP). To investigate the effects of enzyme supplements in barley‐based diets replacing wheat, a 5‐week growth trial was conducted on Pacific white shrimp ( Litopenaeus vannamei ). Six isonitrogenous (~35%) and isolipidic (~8%) diets were formulated, namely, whole wheat‐based (17.42%) basal diet (BW); barley‐based basal diet (BB); and four enzyme‐supplemented diets were BB supplemented with either xylanase (XYL) or a multienzymatic solution (MES) which contains pectinase, protease, phytase, β‐glucanase, XYL, cellulase, and amylase. XYL and MES amount was determined based on manufacturers’ recommended dose (low, L) (0.01 and 0.05 g/100 g diet, respectively) and double the recommended dose (high, H) (0.02 and 0.10 g/100 g diet, respectively) and denoted as BB:XYL‐L, BB:XYL‐H, BB:MES‐L, and BB:MES‐H. Shrimp (0.72 ± 0.03 g) were stocked in 108‐L aquaria. Diets were randomly assigned, with six tanks per treatment. At the completion of the trial, growth performance, apparent digestibility coefficients (ADCs), and physiological gene expression in hepatopancreas were analyzed. Growth parameters showed no significant differences ( p   > 0.05). However, significant differences in ADC of energy ( p = 0.010) and dry matter ( p = 0.001) were observed. The BB:XYL‐L diet significantly increased energy digestibility compared to BB group. No significant differences in hepatopancreatic gene ( tor , tghsr1l , cat , tgfβ , propo , lgbp , and hsp70 ) expression were detected among treatments ( p   > 0.05), although clustering patterns suggested similarity between multienzyme and wheat‐based diets. Overall, barley can replace wheat in Pacific white shrimp diets without impairing growth, while XYL supplementation may improve energy utilization.