Soluble fraction of sardine protein hydrolysates in the feeding of the South American catfish

Abstract

The objective of this study was to evaluate the effect of the inclusion of the soluble fraction of sardine protein hydrolysate on the stability of diets and the excretion of ammonia in South American catfish. Seven experimental diets were prepared with soluble fractions of sardine muscle and viscera hydrolysates. The stability of the pellets in the water was determined at different time intervals (5 min, 10 min, 20 min, 30 min, 1 h and 1.5 h). Total ammonia was determined every five hours. Significant difference was detected for the stability only at 5 minutes, which, the feed containing 20% muscle soluble hydrolysate demonstrated a higher leaching rate when compared to the control diet. Starting at 10 hours of observation, the ammonia concentration was higher in the control when compared to the other treatments. The sardine waste protein hydrolysate demonstrated to be a promising alternative protein source for South American catfish feeds and decreased the environmental impact from the diets. The inclusion of up to 10% of the soluble fraction of the sardine muscle and viscera hydrolysates had no effect on the stability of diets, however, the ammonia excretion was reduced.