Feeding frequency affects growth of juvenile cobia Rachycentron canadum cultured in near-shore cages

Abstract

Growth performance of juvenile cobia Rachycentron canadum (15.7 ± 0.4 g; mean ± SD) reared in 1 m³ near-shore cages, 24.0 ± 2.1°C, fed a Brazilian commercial feed (45% crude protein and 16% lipid) until apparent satiation, in a single feeding (F1), two (F2) or three (F3) feedings per day, for 30 days was assessed. The initial stocking density was 0.6 kg m^-3. Production performance of juvenile cobia was affected significantly by feeding frequency. Groups fed two and three equal feedings per day presented greater and more efficient growth than F1 groups. There was no difference between F2 and F3 treatments for weight gain (15.6 ± 1.5 g and 16.3 ± 2.0 g, respectively), specific growth rate (SGR: 2.3 ± 0.3% and 2.5 ± 0.4% of body weight per day, respectively) and feed conversion ratio (FCR: 2.3 ± 0.2 and 2.5 ± 0.3, respectively). However, these parameters were reduced in F1 treatment (weight gain of 8.4 ± 1.1 g; SGR = 1.4 ± 0.2% and FCR = 3.2 ± 0.6) (P<0.05). The coefficient of variation was inversely proportional to the increase in feeding frequency. There was no significant difference in terms of survival rates, being superior to 90% in all treatments. We suggest that growth performance of juvenile cobia cultured in near-shore cages can be optimized at a feeding frequency of two times a day, facilitating husbandry procedures and minimizing costs  related to labor and vessel utilization.