DIGESTIBILITY OF DRY-EXTRUDED SEAFOOD PROCESSED WASTED BLENDED WITH PLANT PROTEINS FOR RED DRUM (Sciaenops ocellatus)

The increasing of fishmeal price has prompted researchers to seek sustainable alternative protein ingredients for aquafeeds. Seafood processing plants typically have to pay to dispose of their processing wastes (e.g., fish viscera, heads, skin and bones). Therefore, the aim of this study was to develop some alternative marine and plant protein blends by dry extrusion and assess their nutritional value. The products included six dried-extruded blends of soybean meal (SBM) and distillers dry grains with solubles (DGGS) with seafood waste (SFW) from filleting marine fish in three different ratios (50:50, 40:60 and 30:70, of plant proteins and SFW, respectively). A reference diet (REF) was formulated with 36% crude protein and yttrium oxide (Y₂O₃) was used as an inert marker. Test diets were obtained by replacing 30% of the reference diet by the various blends. Each diet was randomly assigned to two tanks and 45 red drum (~70 g) were stocked in 1000-L round fiberglass tanks and fed to apparent satiation once daily. For four weeks fecal material were collected by stripping from the lower intestine, pooled by tank, dried at 60˚C overnight and stored at -20˚C prior to analysis. Apparent digestibility coefficients were determined based on the percentage of the nutrient and Y₂O₃ in the diet and feces. Results of apparent digestibility coefficient values for protein in the diets and ingredients are presented on Table 1. Results for ADC of energy and amino acids are still pending. This results will be further used for a feeding trial in which fishmeal will be replaced by the blends with diets formulated on a digestible protein and energy basis.