Desempenho de juvenis de pregado (Scophthalmus maximus) em função da densidade de estocagem e de níveis dietéticos de L-carnitina

A aquicultura de pregado (Scophthalmus maximus) utilizando elevadas densidades pode reduzir o crescimento e aumentar os custos de produção. Elevados níveis de metabolitos gerados nestes sistemas intensivos provocam rápida deterioração da qualidade da água, podendo também comprometer a performance da produção. A L-carnitina atua como potenciadora do crescimento parecendo ser promissora por atenuar alguns desses efeitos. Os efeitos de densidades (4, 8, 11 e 14 kg m²) no desempenho do crescimento, composição corporal foram avaliados em pregados (75,6 ± 2,8 g) alimentados durante 75 dias a dois níveis dietéticos de L-carnitina (40 ou 240 mg kg¹). Após esse período, determinou-se a excreção de amônia pós-prandial durante 24 horas. Os peixes cultivados na menor densidade, 4 kg m², apresentaram melhores taxas de crescimento e ganho de peso (94-96 g) em comparação aos mantidos em altas densidades (80-87 g). A taxa de eficiência proteica foi mais elevada a 4 kg m² (1,33-1,36), do que a densidades de 8 kg m² (0,98) ou 14 kg m² (0,45). A ingestão voluntária de alimento decresceu de 0,70 para 0,56% do peso corporal com o incremento da densidade. A suplementação de carnitina não afetou o crescimento e a composição corporal, com exceção do conteúdo de carnitine da carcaça que passou de 75 a 128 mg kg¹. Peixes alimentados com suplementos de 240 mg L-carnitina apresentam excreção de amônia mais baixa comparativamente aos alimentados com 40 mg L-carnitina (p < 0,05).Commercial farming of turbot (Scophthalmus maximus) at high stocking densities may lead to growth depression and increasing production costs. Moreover, the high levels of accumulated waste in an intensive system may cause rapid deterioration of water quality, which may undermine the production. L-carnitine is known as a growth-enhancer which shows promise as mitigator of crowding effects. The effects of stocking densities (4, 8, 11 and 14 kg m²) on growth performance, feed utilization and body composition were evaluated during 75 days on turbot (75.6 ± 2.8 g) fed two dietary L-carnitine levels (40 or 240 mg kg¹). At the end of the feeding trial, total ammonia excretion (TAN) was measured postprandially for 24h. Specific growth rate and weight gain decreased with increasing stocking density. Fish held at 4 kg m² had higher final body weight (94-96 g) than fish held at higher densities (80-87 g). Protein efficiency ratio was higher in fish held at 4 kg m² (1.33-1.36), in comparison to fish stocked at 8 kg m² (0.98) or 14 kg m² (0.45). Voluntary feed intake decreased from 0.70 to 0.56% BW with increasing stocking density. Dietary L-carnitine supplementation did not affect growth performance and body composition, except for body L-carnitine content which increased from 75 to 128 mg kg¹ BW with supplementation. Fish fed 240 mg L-carnitine supplements had lower TAN that the ones fed 40 mg L-carnitine (p < 0.05)

Performance of juvenile turbot (Scophthalmus maximus) fed varying dietary L-carnitine levels at different stocking densities

Commercial farming of turbot (Scophthalmus maximus) at high stocking densities may lead to growth depression and increasing production costs. Moreover, the high levels of accumulated waste in an intensive system may cause rapid deterioration of water quality, which may undermine the production. L-carnitine is known as a growth-enhancer which shows promise as mitigator of crowding effects. The effects of stocking densities (4, 8, 11 and 14 kg m²) on growth performance, feed utilization and body composition were evaluated during 75 days on turbot (75.6 ± 2.8 g) fed two dietary L-carnitine levels (40 or 240 mg kg¹). At the end of the feeding trial, total ammonia excretion (TAN) was measured postprandially for 24h. Specific growth rate and weight gain decreased with increasing stocking density. Fish held at 4 kg m² had higher final body weight (94-96 g) than fish held at higher densities (80-87 g). Protein efficiency ratio was higher in fish held at 4 kg m² (1.33-1.36), in comparison to fish stocked at 8 kg m² (0.98) or 14 kg m² (0.45). Voluntary feed intake decreased from 0.70 to 0.56% BW with increasing stocking density. Dietary L-carnitine supplementation did not affect growth performance and body composition, except for body L-carnitine content which increased from 75 to 128 mg kg¹ BW with supplementation. Fish fed 240 mg L-carnitine supplements had lower TAN that the ones fed 40 mg L-carnitine (p < 0.05)

Adornos corporais em Carajás: a produção de contas líticas em uma perspectiva regional

Resumo O sítio arqueológico MMA-02, encontrado na Serra dos Carajás, Pará, e associado à variante amazônica da tradição Tupiguarani era um local especializado na produção de adornos corporais em uma matéria prima lítica, a caulinita silicificada. Principalmente, contas discoides estariam sendo produzidas, o que está evidente na predominância de suas pré-formas e restos brutos de debitagem. Para o presente artigo, foi feita a análise tecnológica de uma amostra do material, centrada no estudo da cadeia operatória das contas, com o objetivo de acessar as escolhas feitas por aqueles que frequentaram o sítio: quais as técnicas utilizadas e como se encadeavam em sucessivas operações no trabalho do material. Ao mesmo tempo, procuramos entender o sítio, tanto dentro do padrão observado para as ocupações Tupiguarani no sudeste amazônico, quanto no contexto mais amplo da região amazônica durante a Nossa Era, na qual a referência à circulação de adornos corporais é uma constante

Growth and osmoregulation in Salmo salar L. juveniles 1+, 1½ + and 2+ reared under restrained salinity

The freshwater phase of Atlantic salmon Salmo salar L vary between one and eight years. The reduction of the freshwater phase is desirable to reduce freshwater usage, human resources and to increase year round availability of pan-sized salmon. Three trials were conducted to investigate the possibility of supply the market in a year-round basis, with pan-sized Atlantic salmon Salmo salar L. (250-300 g) in Portugal (southern limit of the natural distribution of this species). This study primarily aimed to compare the osmoregulatory ability and growth of different fish sizes, smolts 1+ (trial 1), 1.5+ (trial 2) and 2+ (trial 3), in freshwater and seawater conditions. Additionally, effects of photoperiod were determined in smolts 1.5+ (trial 2) for both freshwater and seawater groups. The increments in the plasma osmolality and chlorine concentrations after seawater transfer suggest an identical development in the hypo-osmoregulation capacity among the different age classes. In all trials, weight gain was smaller after 30 d of saltwater transfer when compared to fish reared in freshwater. However, the growth depression was temporary. Seawater group showed a compensatory growth in the immediate months, which permitted an improvement in growth rates. At the end of trials there were minor differences on growth performance between freshwater and seawater groups. Specific growth rates varied between 0.7 and 1.0 % day-1, according to the age and /or size and transfer season

Dietary Oil Source and Selenium Supplementation Modulate Fads2 and Elovl5 Transcriptional Levels in Liver and Brain of Meagre (Argyrosomus regius)

The meagre (Argyrosomus regius) is taking on increasing importance in the aquaculture industry. In view of the limited supply of fish oil (FO) as a feed ingredient, the study of the capacity to biosynthesize long-chain polyunsaturated fatty acids (LC-PUFA) from alternative dietary oil sources is important. We analyzed changes in fatty acid (FA) desaturase 2 (fads2) and FA elongase 5 (elovl5) mRNA levels in livers and brains in response to FO replacement with a blend of vegetable oils (VO) and selenium (Se) supplementation. Fish were fed for 60 days with either a diet containing FO or a diet including VO, each supplemented or not with organic Se. Results showed that fads2 and elovl5 transcription was higher in liver when fish were fed VO diets. The brain mRNA levels of both genes were not affected by the dietary replacement of FO by VO. FA composition in the liver and skeletal muscle was altered by FO replacement, particularly by decreasing eicosapentaenoic acid and docosahexaenoic acid contents. The α-linolenic, linoleic, and arachidonic acid contents increased in both liver and brain of fish fed VO diets. The effect of Se supplementation on lipid metabolism was evident only in fish fed FO, showing a decrease in the transcription of hepatic fads2. Results indicate that the total replacement of FO by VO in diets modulates the expression of genes involved in LC-PUFA biosynthesis in meagre, affecting the FA profile of the fish flesh.Fil: Silva Brito, Francisca. Universidad de Porto; PortugalFil: Magnoni, Leonardo Julián. Universidad de Porto; Portugal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Fonseca, Sthelio Braga. Universidade Federal da Paraíba; Brasil. Universidade Federal de Campina Grande; BrasilFil: Peixoto, Maria João. Universidad de Porto; PortugalFil: Castro, L. Filipe C.. Universidad de Porto; PortugalFil: Cunha, Isabel. Universidad de Porto; PortugalFil: de Almeida Ozório, Rodrigo Otávio. Universidad de Porto; PortugalFil: Magalhães, Fernando Antunes. Universidad de Porto; PortugalFil: Magalhães Gonçalves, José Fernando. Universidad de Porto; Portuga