Common moist diet replacement to promote sustainable Cobia Rachycentron canadum (Linnaeus) near - shore farming in Brazil

Cobia is one of the most promising warm water aquaculture species. In Brazil, cobia farming began in 2008 in the state of Rio de Janeiro from experimental scale facilities to regular near-shore farms based on fresh/frozen fish diets composed mostly of Sardinella sp. Despite the encouraging results achieved in the promotion of sustainable cobia farming, we advocate the replacement of fresh/frozen fish by a practical formulated feed. This experiment evaluated the zootechnical performance and environmental efficiency of moist and practical formulated feeds in early grow-out phases in the cycle of cobia nearshore cage culture. Four hundred and twenty juvenile cobia (151 ± 7 g) were fed with moist feed and practical formulated feed for 56 days. Biometrics were taken every two weeks and diets were analyzed for proximate composition, fatty acid composition and pellet quality. Although growth performance was equivalent between treatments, feed consumption and feed conversion ratios (FCR) were different (p < 0.05) and varied according to water temperature. Cobia fed moist feed exhibited an FCR two times higher than those fed formulated feed. Elevated settling speed and low floatability contributed to higher heterogeneity and lower efficiency of fish fed moist diet. Nitrogen excretion rate was reduced (64 %) and protein efficiency ratio elevated (27 %) within formulated diet groups in comparison to those fed moist diet (79 % and 15 %, respectively). The fatty acid profile of cobia muscle was similar across the groups. With no negative effects of diet substitution on production performance and improvement of environmental efficiency, this approach can be applied and advocated globally and contribute to the responsible intensification of sustainable marine fish culture.

Common moist diet replacement to promote sustainable Cobia Rachycentron canadum (Linnaeus) near - shore farming in Brazil

Cobia is one of the most promising warm water aquaculture species. In Brazil, cobia farming began in 2008 in the state of Rio de Janeiro from experimental scale facilities to regular near-shore farms based on fresh/frozen fish diets composed mostly of Sardinella sp. Despite the encouraging results achieved in the promotion of sustainable cobia farming, we advocate the replacement of fresh/frozen fish by a practical formulated feed. This experiment evaluated the zootechnical performance and environmental efficiency of moist and practical formulated feeds in early grow-out phases in the cycle of cobia nearshore cage culture. Four hundred and twenty juvenile cobia (151 ± 7 g) were fed with moist feed and practical formulated feed for 56 days. Biometrics were taken every two weeks and diets were analyzed for proximate composition, fatty acid composition and pellet quality. Although growth performance was equivalent between treatments, feed consumption and feed conversion ratios (FCR) were different (p < 0.05) and varied according to water temperature. Cobia fed moist feed exhibited an FCR two times higher than those fed formulated feed. Elevated settling speed and low floatability contributed to higher heterogeneity and lower efficiency of fish fed moist diet. Nitrogen excretion rate was reduced (64 %) and protein efficiency ratio elevated (27 %) within formulated diet groups in comparison to those fed moist diet (79 % and 15 %, respectively). The fatty acid profile of cobia muscle was similar across the groups. With no negative effects of diet substitution on production performance and improvement of environmental efficiency, this approach can be applied and advocated globally and contribute to the responsible intensification of sustainable marine fish culture.(AU)

Feeding frequency affects growth of juvenile cobia Rachycentron canadum cultured in near-shore cages / Efeito da frequência alimentar no crescimento de juvenis de bijupirá Rachycentron canadum criados em tanques tipo near-shore

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 ºC, fed a Brazillian 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 significantly affected 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 suggestthat 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.(AU)

O desempenho de juvenis de bijupirá Rachycentron canadum (15,7 ± 0,4 g; média ± DP) criados em tanques-rede de 1 m³, em uma baía protegida, 24,0 ± 2,1 C, alimentados com uma ração comercial brasileira (45% de proteína bruta e 16% de gordura) até saciedade aparente, alimentados em uma (F1), duas (F2) e três (F3) refeições por dia, durante 30 dias, foi avaliado. A densidade de estocagem inicial foi de 0,6 kg m-3. O desempenho de produção de juvenis de bijupirá foi afetado significativamente pela frequência alimentar. Grupos alimentados duas e três vezes ao dia apresentaram um crescimento maior e mais eficiente do que os grupos F1. Não houve diferença entre os tratamentos F2 e F3 para o ganho em peso (15,6 ± 1,5 g e 16,3 ± 2,0 g, respectivamente), taxa de crescimento específica (TCE: 2,3 ± 0,3% e 2,5 ± 0,4% do peso corporal diário, respectivamente) e conversão alimentar aparente (CAA: 2,3 ± 0,2 e 2,5 ± 0,3, respectivamente). No entanto, os tratamentos F2 e F3 promoveram melhores resultados comparados ao tratamento F1 (ganho em peso: 8,4 ± 1,1 g; TCE = 1,4 ± 0,2%; CAA = 3,2 ± 0,6) (p 0,05). O coeficiente de variação foi inversamente proporcional ao aumento da frequência alimentar. Não houve diferença significativa para taxa de sobrevivência, sendo superior a 90% em todos os tratamentos. Este trabalho sugereque o desempenho do crescimento de juvenis de bijupirá criados em condições do presente estudo pode ser otimizado quando alimentados duas vezes ao dia, facilitando os procedimentos de criaçãoe minimizando os custos relacionados com mão-de-obra e embarcação.(AU)

Feeding frequency affects growth of juvenile cobia Rachycentron canadum cultured in near-shore cages / Efeito da frequência alimentar no crescimento de juvenis de bijupirá Rachycentron canadum criados em tanques tipo near-shore

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 ºC, fed a Brazillian 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 significantly affected 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 suggestthat 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.

O desempenho de juvenis de bijupirá Rachycentron canadum (15,7 ± 0,4 g; média ± DP) criados em tanques-rede de 1 m³, em uma baía protegida, 24,0 ± 2,1 C, alimentados com uma ração comercial brasileira (45% de proteína bruta e 16% de gordura) até saciedade aparente, alimentados em uma (F1), duas (F2) e três (F3) refeições por dia, durante 30 dias, foi avaliado. A densidade de estocagem inicial foi de 0,6 kg m-3. O desempenho de produção de juvenis de bijupirá foi afetado significativamente pela frequência alimentar. Grupos alimentados duas e três vezes ao dia apresentaram um crescimento maior e mais eficiente do que os grupos F1. Não houve diferença entre os tratamentos F2 e F3 para o ganho em peso (15,6 ± 1,5 g e 16,3 ± 2,0 g, respectivamente), taxa de crescimento específica (TCE: 2,3 ± 0,3% e 2,5 ± 0,4% do peso corporal diário, respectivamente) e conversão alimentar aparente (CAA: 2,3 ± 0,2 e 2,5 ± 0,3, respectivamente). No entanto, os tratamentos F2 e F3 promoveram melhores resultados comparados ao tratamento F1 (ganho em peso: 8,4 ± 1,1 g; TCE = 1,4 ± 0,2%; CAA = 3,2 ± 0,6) (p 0,05). O coeficiente de variação foi inversamente proporcional ao aumento da frequência alimentar. Não houve diferença significativa para taxa de sobrevivência, sendo superior a 90% em todos os tratamentos. Este trabalho sugereque o desempenho do crescimento de juvenis de bijupirá criados em condições do presente estudo pode ser otimizado quando alimentados duas vezes ao dia, facilitando os procedimentos de criaçãoe minimizando os custos relacionados com mão-de-obra e embarcação.