Catfish processing generates large volumes of heads, skin, frames, and viscera that are often underutilized. Valorizing these by-products into a protein-rich ingredient supports aquaculture sustainability. Fermented silage is a practical method that preserves raw materials through lactic acid fermentation while promoting protein hydrolysis, yielding a by-product hydrolysate. This hydrolysate can be further processed into ingredients or additives for aquafeeds. This study evaluated the catfish by-product hydrolysate (CFPH) as a palatability enhancer in a feed preference trial with Pacific white shrimp (Litopenaeus vannamei).
Two feed preference trials were conducted following a crossover, repeated measures design. Fifty Pacific white shrimp (~10 g/shrimp) stocked into five tanks (10 shrimp/tank). In both trials, shrimp were offered five isonitrogenous (35% crude protein) and isolipidic (10%) diets: a fish-meal control containing 35% fishmeal (FM-35), a soybean meal-based negative control (NCTL), and test diets with 5% ingredient inclusion: krill meal (KM), hydrolyzed fish protein concentrate (HFPC), catfish by-product hydrolysate (CFPH), and hydrolyzed tuna by-product (TPH). Pre-weighed diets were offered on two submerged trays per tank, one with the reference diet and the other with a test diet. In Trial 1, the NCTL served as the reference, and in Trial 2, the FM-35 was used as the reference. Shrimp were fed twice daily for 10 days, with diets provided in excess during 1-h feeding periods. To avoid positional influence, the tray placement was alternated between a.m. and p.m. feedings. After 1 h, trays were removed, uneaten feed was collected, dried for 3 h at 120°C, and weighed. Feed preference was evaluated based on the Apparent Feed Intake (AFI, %) and Relative Consumption (RC, %). Data were analyzed by a two-way repeated measures ANOVA using Student’s t-test and Tukey’s HSD test. In Trial 1, shrimp fed the CFPH diet showed the highest AFI (~88%), significantly higher than those on all other diets. The FM-35, KM, HFPC and TPH diets also resulted in higher intake than the NCTL but did not differ from each other (Figure 1). Similarly, shrimp fed the CFPH diet showed the highest RC (~300%), followed by those fed with TPH (~250%). In Trial 2, shrimp fed the CFPH diet also showed the highest AFI (~87%), significantly higher than the FM-35. Shrimp fed TPH showed similar intake to FM-35, whereas those fed KM and HFPC exhibited significantly lower AFI. Overall, shrimp fed the CFPH diet showed higher feed intake and relative consumption in both trials, suggesting good acceptance and preference for the hydrolyzed catfish by-product.