Objective
The aim of the proposed research is to provide a scientific and technological basis for the definition of the most cost-effective method for feeding sea bass, Dicentrarchus labrax. Through this research the general objective of the programme is to provide data for: minimisation of feeding labour; minimisation of feed loss from the system; minimisation of feed-fish conversion ratio increasing of daily food intake.
The objectives of minimising the food conversion ratio and increasing the daily intake of food being generally incompatible, the primary aim of the project is unlikely to be that which achieves the best conversion efficiency or the maximum food intake but will be a compromise between the two.
Research was based on a comparison of series of triplicate sea bass rearing experiments using 4 different feeding methods most commonly used in aquaculture: manual, automatic continuous, a combination of automatic and manual, self feeding.
The lowest growth and transformation performances observed with the automatic feeding are due to: technical problems linked to humidity, excessive marine turbulence and power failures; a discrepancy between the quantity of food offered and demand; a discrepancy between of the rations recommended by the manufacturer. The rations given by the weight temperature matrix are, in the majority, overestimations due to the fact that the maximum ad libitum values encountered on certain days are assimilated in the weekly average values.
The self feeding method permitted the most appropriate balance between feed offered and the daily demand. The lowest transformation performance in self feeding fish weighing 100 to 400 g when compared to hand fed fish was due to accidental activation of the self feeder and the subsequent overconsumption due to visual stimulation.
The manual feeding method allowed a good quantification of food offered and demand. Under the experimental conditions it is easy to define when the fish are sated and to observe the remaining food. This is more difficult in commercial conditions.
Considering a redefinition of the existing feeding tables for the sea bass, it is concluded that all the tested technologies offer similar growth and conversion indexes, and therefore present the same cost efficiency for the food and the same impact on the environment per kilo of produced fish. With regard to the cost efficiency of the feeding techniques, the self feeding method appeared to be the most effective, due to the low cost of the initial investments, the longevity of the product, the ease of implementation and management, the decreased labour costs and the subsequent possibility of food regulation in the case of management problems (eg sickness, temperature variations).
The research is based on a comparison of a series of triplicate sea bass rearing experiments with the 4 different feeding methods most commonly used in aquaculture.
The manual method 2 times a day (morning and evening) ad libitum. This method, which is the most common, allows a good adequation between feeding and fish needs but is labour expensive. The automatic continuous method distribution in day light with a prescribed ration proposed by the feeding tables according to the fish size and the temperature. This method, which is often used in cage culture, is not so labour demanding but does not allow so good survey of fish needs. A combination of automatic and manual distribution. In this case, automatic feeders are employed during daylight hours to feed approximately 80% of the ad libitum ration and this is supplemented by careful handfeeding to slightly below the ad libitum level. This compromise method can provide a saving of both feed and labour costs. The self feeding method in which the fish choose themselves (even at the night) the moment of feeding and the amount they require.
The experiments will be performed with fish of 1, 5, 10, 25, 50, 100, 250 and 500 grams, which represents the entire biological range from pregrowing to on-growing-finition phase.
Trials will be monitored, and results will be analysed according to the classical method used in aquaculture research (i.e. Biogestion and Bilan method) detailed in DIVANACH, 1985. Temperature, salinity, dissolved oxygen, mortality, general health state, ammonia, will be monitored daily. Growth, conversion ratio, mortality rate, will be monitored weekly.
Feeding behaviour will be recorded with a video system linked to a computer enabling image analysis which has been described by Spratt, 1988.
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
- agricultural sciencesagriculture, forestry, and fisheriesfisheries
- social sciencessociologydemographymortality
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711.10 Iraklion - Crete
Greece