Résumé
Large-scale lab culture of Ankistrodesmus gracilis and Diaphanososma birgei were evaluated by studying the biology and biochemical composition of the species and production costs. Ankistrodesmus gracilis presented exponential growth until the 6th day, with approximately 144 x 10(4) cells.mL-1, followed by a sharp decrease to 90 x 10(4) cells.mL-1 (8th day). Algae cells tended to increase again from the 11th day and reached a maximum of 135 x 10(4) cells.mL-1 on the 17th day. D. birgei culture showed exponential growth until the 9th day with 140 x 10² individuals.L-1, and increased again as from the 12th day. Algae A. gracilis and zooplankton D. birgei contain 47 to 70 percent dry weight protein and over 5 percent dry weight carbohydrates. The most expensive items in the context of variable costs were labor and electricity. Data suggested that temperature, nutrients, light availability and culture management were determining factors on productivity. Results indicate that NPK (20-5-20) may be used directly as a good alternative for mass cultivation when low costs are taken into account, promoting adequate growth and nutritional value for cultured A. gracilis and D. birgei.
O objetivo deste trabalho foi avaliar o cultivo em larga escala de Ankistrodesmus gracilis e Diaphanososma birgei em laboratório através do estudo da biologia das espécies, composição bioquímica e custo operacional de produção. A. gracilis apresentou um crescimento exponencial até o sexto dia, ao redor de 144 x 10(4) células mL-1. Logo em seguida, sofreu um brusco decréscimo apresentando 90 x 10(4) células mL-1 (oitavo dia). A partir do décimo primeiro dia, as células algais tenderam a crescer novamente, apresentando um máximo de 135 x 10(4) células mL-1 no 17º dia. No cultivo de D. birgei, foi observado o primeiro pico de crescimento no nono dia com 140 x 10² indivíduos L-1, aumentando novamente a partir do décimo segundo dia. A alga clorofícea A. gracilis e o zooplâncton D. birgei possuem aproximadamente 50 e 70 por cento de proteína (PS), respectivamente, com teor de carboidrato acima de 5 por cento. A eletricidade e mão de obra foram os itens mais dispendiosos e, de acordo com os dados obtidos, a temperatura, nutrientes, disponibilidade de luz e manejo do cultivo, foram fatores determinantes sobre a produtividade. Os resultados indicam que o meio NPK (20-5-20) pode ser utilizado diretamente como uma alternativa de cultivo em larga escala, considerando o baixo custo de produção, promovendo adequado crescimento e valor nutricional para A. gracilis e D. birgei.
Sujets)
Animaux , Chlorophyta/croissance et développement , Milieux de culture , Cladocera/croissance et développement , Chlorophyta/composition chimique , Cladocera/composition chimique , Milieux de culture/économie , Laboratoires/économie , Valeur nutritive , Croissance démographique , Facteurs tempsRésumé
The objective of the present work was to investigate the influence of four diets on population growth, development, total length, dry weight, and nutritional value of two zooplanktonic species, Moina micrura and Diaphanosoma birgei. The four dietary treatments were: algae alone (A); algae + vitamins (AV); algae + ration (AR); and algae + ration + vitamins (ARV). Growth rate peak for both species occurred faster with AV treatment. In general, AV treatment for M. micrura showed better results for intrinsic rate, fecundity, and embryonic and post-embryonic development. On the other hand, longevity and total spawning number were better with AR treatment (p < 0.05). Vitamin and ration treatments produced the best results in D. birgei species (p < 0.05). The highest percentage of protein and lipids for both cladocerans was verified for ration treatments. Carbohydrate was higher for the treatment containing algae alone (p < 0.05). Generally, diets containing ration and vitamin showed better results in cladocerans development, with water quality adequate for culture systems. Ration and vitamin diets may also be used in high-density cultures in the laboratory