Growth, body composition and hematology of juvenile pacu (Piaractus mesopotamicus) fed increasing levels of ractopamine / Crescimento, composição corporal e hematologia de juvenis de pacu (Piaractus mesopotamicus) alimentados com quantidades crescentes de ractopamina

The effects of four levels of dietary ractopamine (RAC) on growth, body composition and hematology of pacu, Piaractus mesopotamicus juveniles (103.6±3.3g) were studied. Fish were housed into 12 circular tanks of 1 m3 - 15 fish per tank - and fed for 60 days with practical diets supplemented with 0; 10; 20 or 40mg RAC per kg of diet, in a totally randomized design trial (n=3). Fish fed diets containing up to 40mg RAC/kg diet for 60 days did not have improved growth or body composition parameters. There were no significant differences in hematocrit, hemoglobin and mean corpuscular hemoglobin. Plasma glucose and triglycerides were significantly smaller in fish fed with RAC; however no significant differences between RAC levels were detected. The inclusion of up to 40mg RAC/kg of diet did not improve growth and body composition, but influenced some hematological and biochemical parameters of juvenile pacu.

Estudou-se o efeito de quatro quantidades de ractopamina dietética (RAC) sobre o crescimento, a composição corporal e a hematologia de juvenis de pacu, Piaractus mesopotamicus (103,6±3,3g). Os peixes foram distribuídos em 12 tanques circulares de 1m3 - 15 peixes por tanque - e alimentados por 60 dias com dietas práticas suplementadas com 0, 10, 20 ou 40mg RAC/kg de ração, em um delineamento inteiramente casualizado (n=3). Os peixes alimentados por 60 dias com dietas contendo até 40mg RAC/kg não apresentaram melhora no crescimento ou na composição corporal. Não houve diferença significativa nas concentrações de hematócrito, hemoglobina e hemoglobina corpuscular média. Glicose e triglicerídeos plasmáticos foram significativamente menores nos peixes alimentados com RAC, entretanto não houve diferença significativa entre os níveis de RAC. A inclusão de até 40mg RAC/kg de ração não melhorou o crescimento ou a composição corporal, mas influenciou alguns parâmetros hematológicos e bioquímicos de juvenis de pacu.

Depletion study and estimation of the withdrawal period for oxytetracycline in tilapia cultured in Brazil.

Defining pharmacokinetic parameters and depletion intervals for antimicrobials used in fish represents important guidelines for future regulation by Brazilian agencies of the use of these substances in fish farming. This article presents a depletion study for oxytetracycline (OTC) in tilapias (Orechromis niloticus) farmed under tropical conditions during the winter season. High performance liquid chromatography, with fluorescence detection for the quantitation of OTC in tilapia fillets and medicated feed, was developed and validated. The depletion study with fish was carried out under monitored environmental conditions. OTC was administered in the feed for five consecutive days at daily dosages of 80 mg/kg body weight. Groups of ten fish were slaughtered at 1, 2, 3, 4, 5, 8, 10, 15, 20, and 25 days after medication. After the 8th day posttreatment, OTC concentrations in the tilapia fillets were below the limit of quantitation (13 ng/g) of the method. Linear regression of the mathematical model of data analysis presented a coefficient of 0.9962. The elimination half-life for OTC in tilapia fillet and the withdrawal period were 1.65 and 6 days, respectively, considering a percentile of 99% with 95% of confidence and a maximum residue limit of 100 ng/g. Even though the study was carried out in the winter under practical conditions where water temperature varied, the results obtained are similar to others from studies conducted under controlled temperature.

Community ecology of metazoan parasites of the anchovy Anchoa tricolor (Osteichthyes: Engraulidae) from the coastal zone of the State of Rio de Janeiro, Brazil.

Between October 2001 and March 2002, 103 specimens of A. tricolor from Angra dos Reis (23 degrees 01' S, 44 degrees 19' W), in the coastal zone of the State of Rio de Janeiro, Brazil, were analyzed in order to study their metazoan parasite infracommunities. Ten species of metazoan parasites were collected: 4 digeneans, 1 cestode, 1 acantocephalan, 2 nematodes, 1 copepod, and 1 hirudinean; 77.7% of the fishes were parasitized by one or more metazoan, with a mean of 3.5 +/- 6.2 parasite/fish. Digenean was the most dominant with 4 species that accounted for 53.2% of the total parasites collected; Ergasilus sp. was the most abundant species. Abundance and prevalence of Parahemiurus merus (Linton, 1910) were positively correlated with the total length of host. Relationships between total body length of fish and both total parasite abundance and mean parasite species richness were observed. Mean parasite diversity of species was correlated to host's total length, with significant differences found between male and female fishes. Two pairs of larval species showed significant positive association and covariation. The metazoan parasite infracommunities of A. tricolor presented dominance of larval endoparasites; correlation of parasite abundance, diversity, and species richness with host total length; and low number of parasite interspecific relationships. The parasite community of A. tricolor showed some similarities with the parasite community of another South American Atlantic engraulid.

Community ecology of metazoan parasites of the anchovy Anchoa tricolor (Osteichthyes: Engraulidae) from the coastal zone of the State of Rio de Janeiro, Brazil

Entre outubro de 2001 e março de 2002, foram examinados 103 espécimes de A. tricolor provenientes de Angra dos Reis (23º01'S, 44º19'W), litoral do Estado do Rio de Janeiro, Brasil, para o estudo de suas infracomunidades de metazoários parasitos. Foram coletadas 10 espécies de metazoários parasitos: 4 digenéticos, 1 cestóide, 1 acantocéfalo, 2 nematóides, 1 copépode e 1 hirudíneo; e 77% dos peixes estavam parasitados por 1 ou mais metazoários, com média de 3,5 ± 6,2 parasitos/peixe. Os digenéticos foram dominantes, representando 53,2% do total de parasitos coletados, e Ergasilus sp., a espécie mais abundante. A abundância e a prevalência de Parahemiurus merus (Linton, 1910) foram positivamente correlacionadas ao comprimento total dos hospedeiros. Relações entre a abundância parasitária total e a riqueza parasitária média ao comprimento total dos hospedeiros foram observadas. A diversidade parasitária média foi corrrelacionada com o comprimento total dos hospedeiros, apresentando diferenças significativas entre os peixes machos e fêmeas. Dois pares de espécies de larvas apresentaram associação e covariação positiva significativas. As infracomunidades de metazoários parasitos de A. tricolor demonstraram dominância nas larvas de endoparasitos, correlação entre abundância parasitária, diversidade e riqueza de espécies e o comprimento total dos hospedeiros e o baixo número de associações interespecíficas parasitárias. A comunidade parasitária de A. tricolor apresentou algumas semelhanças com a comunidade parasitária de outros engraulídeos do Atlântico Sul-Americano.