Influence of defensible and indefensible pattern of food delivery upon the development of feeding anticipatory activity (FAA) and growth performance in rainbow trout (Oncorhynchus mykiss)

Abstract

Using two methods of food delivery, defensible (D) and indefensible (ID), the effect of restricted feeding (RF) on the development of feeding anticipatory activity (FAA) and growth performance of rainbow trout (Oncorhynchus mykiss) was investigated. Six glass aquaria (120 × 30 × 80 cm), divided equally into 3 sections of morning, afternoon and evening of location of food delivery each with eight fish were selected for D and ID methods. The fish were subjected to a time-RF schedule for 70 days. Food delivery was restricted to three feeding periods; one hour per feeding session: morning (0800-0900 h), afternoon (1300-1400 h) and evening (1800-1900 h). Food was withheld on days 28, 42, 56 and 70 (test days) to assess FAA by the fish and fish growth parameters were determined at the end of the experiment. The present results clearly indicate that only using an indefensible (ID) pattern of food delivery, rainbow trout can simultaneously anticipate three daily meals and synchronise their feeding activity before the period of food availability and that the best FCR and SGR were achieved when an ID pattern of food delivery was offered. The lack of development of FAA for fish in the D method could be due to development of dominant hierarchies. This led to reduction of most growth parameters in the D method compared to the ID one.