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Effects of the feeding strategy on productive performance in rainbow trout (oncorhynchus mykiss)

Abstract:

An experiment was conducted in the Trujillo State, Venezuela, to evaluate the productive response of two different fed strategies in rainbow trout fingerlings (Oncorhynchus mykiss) affected by social restrictions due to size differences. During 90 days (d), two groups of fish were fed with a commercial balanced feed as follow: T1, five d feeding and two d fasting (5A-2NA) and T2, two d feeding and one d fasting (2A-1NA). Every 15 d the fish weight and length, and the total biomass (kg) were registered. As response variables were considered the feed conversion efficiency (CA), daily growth rate (GDP), specific growth rate (TCE) and survival rate (S). The CA was similar between treatments (T1: 1.28 ± 0.05; T2: 1.37 ± 0.05), although GDP and TCE were greater in T1 than in T2 (GDP: 1,93 ± 0.07 versus 1.68 ± 0.07 for T1 y T2, respectively; P<0.03; TCE: 2.28 ± 0.04 versus 2.14 ± 0.03 for T1 y T2, respectively; P<0,02). In another hand, greater proportion of fish survived in T2 compared to T1 (92.8 versus 94.2 % respectively; P<0.01). The weight-size relationship in both treatments indicated a minorant allometric growth (T1: P=0.046 L2.573; r=0.928; T2: P=0.028 L2.722; r=0.933). In conclusion, the combination of five d feeding with two d fasting (T1) determined the better productive performance.