Fluctuations in ammonia production by eels (Anguilla anguilla L.) as a result of feeding strategy
Poxton, M.G.; Lloyd, N.J. (1989). Fluctuations in ammonia production by eels (Anguilla anguilla L.) as a result of feeding strategy, in: De Pauw, N. et al. Aquaculture: a biotechnology in progress: volume 1. pp. 1125-1135
In: De Pauw, N. et al. (1989). Aquaculture: a biotechnology in progress: volume 1. European Aquaculture Society: Bredene. ISBN 90-71625-03-6. 1-592 pp., more
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Document type: Conference paper
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| Abstract |
The relationships between feeding frequency and ammonia production by European eels (Anguilla anguilla L.) grown in a recirculating freshwater system were examined. The objective was to identify the best feeding strategy from the point of view of overall system management. Fast growing eels, having attained a mean weight of 16.4g after 8 months growth in the system, were fed 2.5% of their body weight per day using a high density "dry" pellet. Before each experiment the eels were given the feeding regime to be tested for at least 7 days to ensure that any previous feed expectancy had been lost. For these experiments 1 202 eels were stocked in a 1 m² tank, the water depth of which was set to 11cm. Water flow-rates varied between 25-35l.min-1 being increased as the fish biomass increased from 26.3 to 34.1kg as a result of fish growth over the experimental period. Seven experiments were conducted to test four feeding regimes, two feeds per day (0930, 1530h) two feeds per day (0830, 2030h), five feeds per day (0830, 1130, 1430, 1730, 2030h) and many feeds per day (automatically every 5-10min for 12h from 0830 to 2030h). The results showed that two feeds per day led to the lowest overall production of ammonia and that the lowest peak concentration occurs when these feeds are widely spaced out. More frequent feeding is time consuming and leads to higher excretion rates, while the use of automatic feeders leads to much higher peak concentrations being experienced. |
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