Efforts to optimize plant-based diets continue to be a key area in aquaculture nutrition research. Among traditional and novel protein feedstuffs with potential for use in aquafeeds is industrial hemp. H empseed meal (HSM) is rich in protein and lipids and might complement other protein sources in feeds for farmed aquatic animals. Yet, information on the nutritional value of HSM for aquatic animals remains limited.
A 7 -week feeding trial was conducted to assess the nutriti onal value of two HSMs (P30 and P50) in practical diets for Pacific white shrimp grown in a recirculating aquaculture system. A conventional soybean meal-based diet (CSBM-C) was formulated to contain 35% crude protein and 10% lipid and was used as the control for HSM inclusion. Five additional diets were formulated to include P30 and P50 at 10% and 20% partially replacing CSBM digestible protein, with one extra P50 diet being formulated without supplemental methionine and lysine. An additional diet (FM-35) formulated to contain 35% fish meal was used as a standard reference for the plant-based formulations. Fifteen hand-sorted shrimp (~ 1.0 g/ shrimp) were stocked into each of 35, 110-L glass aquaria and randomly assigned one experimental diet (n=5 ). Shrimp in each aquarium were fed four times daily based on an expected growth rate of 1.5g/shrimp/week . Water quality parameters were maintained within acceptable ranges for the species . At the conclusion of the feeding trial, data on production performance and whole-body composition was gathered.
After seven weeks of feeding , shrimp survival ranged from 60 to 96.7%, with the lowest survival being observed in the CSBM treatment. Shrimp fed FM-35, P30, and P50_10 diets grew at a rate of 1.6-1.7 g/week, and displayed the lowest FCRs among all groups (P<0.05). Based on the responses of groups fed the P50_20 diets, supplementation of methionine and lysine was unnecessary in these formulations. Additional results on nutrient retention efficiency, whole-body fatty acid, and cannabinoid contents will be presented. Our findings in this study indicate that both HSM products evaluated are good complementary sources of nutrients and energy in plant-based diets for Pacific white shrimp.