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20 pages, 8 figures, 5 tables | The trophic relationships of decapod crustaceans on Le Danois bank (NE of Iberian Peninsula, NE Atlantic Ocean) were studied within the framework of the multidisciplinary project ECOMARG during two surveys, one in October 2003 and the other in April 2004. The diets of eleven species of decapods were analyzed and, within a rather continuous gradient of food source exploitation, 3 trophic groups were identified: (1) plankton feeders, comprising the shrimps Acanthephyra pelagica, Sergia robusta, and Pasiphaea tarda, which preyed on meso-bathypelagic taxa such as euphausiids and calanoids; (2) benthos feeders, comprising the crangonids Pontophilus norvegicus and Pontophilus spinosus, the crab Geryon trispinosus and the shrimp Aristeus antennatus; and (3) an intermediate group, including the rest of species, with mixed diets that included detritus. Among the third group, anomurans (Munida tenuimana, Pagurus alatus, and Parapagurus pilosimanus) consumed phytoplanktonic detritus in April, suggesting a link with peaks of surface Chl a occurring between March and April in the study area. Gut pigment and isotopic (δ13C/δ15N correlations) analyses revealed that assemblages inhabiting the top of the bank (455–612 m) and the inner basin (642–1048 m, close to the Lastres canyon head) had different food sources, with species inhabiting the deepest region exhibiting a stronger dependence on marine snow derivatives. These results are consistent with the higher proportion of mud and sediment organic matter (OM) content in the inner basin (82.2% pellites; 6.3% OM at 1028 m) compared to the top of the Le Danois bank (only 13.9% pellites; 2.8% OM at 485 m), which is a hydrodynamically more active zone. Exploitation of different food sources is also consistent with differences in the trophic level of species, inferred from stable δ15N isotope analyses, which yield values ranging from 6.88‰ for the hermit crab P. alatus to 13.52‰ for the crangonid shrimp P. norvegicus. Stomach fullness was higher in April 2004 than in October 2003, both between and within species of the dominant decapods, including detritus feeders (M. tenuimana) and benthos feeders (e.g. G. trispinosus, P. norvegicus). Most species exhibited a parallel increase in their density in April 2004, with a significant positive correlation between density and stomach fullness. This increase coincides with a peak of surface Chl a concentration occurring in March–April | Pigment analyses were performed thanks to NOW-ALW (Project No. 152911) | Peer reviewed

O objetivo neste trabalho foi avaliar o ganho de peso, a conversão alimentar e os custos com alimentação de novilhos bubalinos em sistema de confinamento. Utilizaram-se 13 bubalinos Murrah castrados (peso vivo médio inicial de 297±9 kg) alimentados com três diferentes dietas (tratamentos): sem lipídeo adicional; óleo de soja; e grão de soja integral. A duração do experimento foi de 84 dias, divididos em três períodos de coleta, cada um com 28 dias. Nos seis últimos dias de cada período, foram coletadas amostras de alimentos, sobras e fezes para determinação do consumo. As dietas foram fornecidas duas vezes ao dia (às 8 e 16h), na forma de ração total, em quantidade ajustada para ocorrer 10 a 20% de sobras. Os animais foram pesados no início do experimento e ao fim de cada período experimental, após jejum de 16 horas. Os ganhos médios diários foram de 990, 1.090 e 1.280 g/dia para os animais alimentados com as dietas sem lipídeo adicional, com grão de soja e com óleo de soja, respectivamente. As conversões alimentares foram melhores nos animais alimentados com a dieta contendo óleo de soja. O custo da dieta com grão de soja foi maior que o das demais. O melhor desempenho e a melhor resposta econômica foram obtidos quando fornecida a dieta com óleo de soja, o que torna viável sua utilização no confinamento de bubalinos.<br>The objective of this trial was to evaluate the effect of different dietary fat sources on weight gain, feed conversion, and feeding costs in feedlot water buffalo steers. Thirteen castrated Murrah steers averaging 297±9 kg of body weigh were assigned to one of the following three treatments: no added fat (control), soybean oil or whole soybean in a completely randomized design. The experiment lasted 84 days with three experimental periods of 28 days each. Samples of feeds, orts and feces were collected in the last six days of each period for determination of intake. Diets were fed twice a day (8 a.m. and 4 p.m.) as total mixed ration and the amount of feed offered was adjusted daily to yield refusals equal to approximately 10 to 20% of intake. Body weight was measured at the beginning and at the end of each experimental period after 16 hours of fasting. The average daily weight gain was 990, 1,090 and 1,280 g/day for animals fed the control, whole soybean, and soybean oil diets, respectively. Feed conversion was greatest in the diet containing soybean oil while that containing whole soybean resulted in the highest costs. The soybean oil diet increased performance and reduced costs; therefore, it can be used to improve meat production in feedlot water buffalo.