Densidade de estocagem e parâmetros eritrocitários de pacus criados em tanques-rede

Abstract

RESUMO -O objetivo neste trabalho foi avaliar o manejo, as características eritrocitárias e o nível de glicose sanguínea de pacus (Piaractus mesopotamicus) estocados em diferentes densidades em tanques-rede. Foram utilizados 2.700 peixes com peso inicial de 142,11 ± 10,54 g, distribuídos em nove tanques-rede de 5 m 3 de volume útil durante 240 dias. O delineamento utilizado foi o inteiramente casualizado, com três densidades (200, 300 e 400 peixes por tanque), cada uma com três repetições. Densities of farming did not influence carcass yield, but they affected total length, which was higher in fish raised in low density, which did not differ from those raised in intermediate density. Fish raised in lower density showed the greatest lipid deposition, but they did not significantly differ from those stocked in intermediate density. Erythrocyte variables like total erythrocytes, hemoglobin, hematocrit, average corpuscular volume, average corpuscular hemoglobin concentrations and average corpuscular hemoglobin did not present statistical differences among the used densities and they remain in the normal range for the species. Levels of glucose in the blood did not differ significantly among the analyzed densities. Stocking densities do not influence erythrocyte parameters, glucose level neither carcass yields of pacu fish. Density 200 fish/cage results in higher final weight and weight gain; however, it reduces productivity per area and increases lipid deposition of the fish. IntroduçãoO Brasil possui inúmeras espécies de peixes autóctones com potencial zootécnico para a criação em tanques-rede. Entre elas, destaca-se o pacu, Piaractus mesopotamicus (Holmberg, 1887 inserir nas referências), que é representante da superordem Ostariophysi, cujos peixes são os de maior valor comercial na pesca e na piscicultura brasileira (Urbinati & Gonçalves, 2005).Muitos fatores podem interferir no período de criação desses peixes. Entre esses fatores, destaca-se a densidade de estocagem, que pode afetar diretamente o crescimento.

Feeding rate for pacu reared in net cages

“…On the other hand, the values of visceral fat found in this experiment showed to be inferior to those found by Bombardelli et al (2007), who achieved 6.55% VSFI for pacu (P. mesopotamicus) in net cages.…”

“…The hyperglycemia found in the present study can be related to the management of animal capture and to their transportation to the place of conduction of blood sampling procedures, where net cages were taken to the border of the reservoir and fish were collected with a hand net. However, they are close to the values found by Bittencourt et al (2010), who achieved 99.95 to 106.55 mg/dL in pacu with different densities; these authors utilized the same methodology of capturing animals.…”

“…Bittencourt et al (2010) found similar values for pacu fishes of approximately one kilogram, for the eviscerated fish (87 to 88%). However, for clean trunk (60%) and filets (45 to 47%), they were superior to the observations in the present study.…”

“…This species is of great importance to aquaculture, for it presents quick growth, rusticity to handling, easy adaptation to artificial feeding and great acceptance by the consumer market (Urbinati & Gonçalves, 2005). Its adaptability to the system of net-cage rearing was proven by Signor et al (2010), who studied the relation between protein and energy and by Bittencourt et al (2010), who verified the best stocking density for the pacu reared in net cages.…”

Individual, spatial and inter-sex variation in somatic growth: a study of Piaractus mesopotamicus (Characiformes: Serrasalmidae), a long-distance freshwater Neotropical migratory fish

“…However, it is notable that studies of same age of the P. mesopotamicus in cultivation cages have shown inter-individual variation in somatic growth when stocking density is altered (Bittencourt et al, 2010). In the current study, variation in growth was explained by individual variation and sex, with the analyzed individuals showing different growth potential.…”