Size-related feeding and gastric evacuation measurements for the Southern brown shrimp Penaeus subtilis

Abstract

Studies attempting to optimise feeding methods in penaeid aquaculture have often relied on results of growth, survival performance and food conversion ratios. At present, data relating to maximum ration, ingestion rates (IRs), faecal production rates (FPs), foregut evacuation and appetite revival are lacking for Penaeus spp. despite their relevance to the development of models aimed at maximising food use in shrimp culture systems. Size-related feeding and gastric evacuation (GE) measurements were determined for Penaeus subtilis by conducting laboratory-based feeding trials on individual animals. A total of 3482 samples of feed and (or) faeces were collected for quantitative analysis derived from 307 shrimp. Food ingestion was a function of shrimp body weight (BW). Feeding intensity increased progressively with shrimp size, but inversely in percentage terms, resulting in a larger faecal production per BW for smaller shrimp. On average, P. subtilis food ingestion was equivalent to 2.3% of its BW per hour, but consumption in shrimp with empty stomachs reached 4.9% BW/h. Foregut clearance rates (13%) peaked 3 h after food recovery, with the bulk of faeces being produced within 1 h. Food load occurred progressively as more feed was given and evacuated from shrimp stomachs, while feeding continued at reduced levels. Data indicated that control of feeding intensity and resumption of food intake by P. subtilis were not markedly affected by the level of their stomach fullness or by longer food administration intervals. The daily administration of food in shorter feeding intervals, although at continually reduced amounts, may be advantageous in the culture of P. subtilis.