Feeding and growth of glass eels, Anguilla anguilla L.: the effect of feeding stimulants on feed intake, energy metabolism and growth |
| |
| Authors: | L T N HEINSBROEK J G KREUGER |
| |
| Institution: | Department of Fish Culture and Fisheries, Agricultural University Wageningen, Wageningen, The Netherlands |
| |
| Abstract: | Abstract. Two experiments were conducted in which glass eels, Anguilla anguilla L., were fed with six different diets. Two natural diets, cod roe and minced bovine spleen, and four artificial diets, an unflavoured trout fry crumble and three trout fry crumble diets with added feeding stimulants, were used. The feeding stimulants tested were cod roe extract, spleen extract and a mixture of synthetic L-amino acids. In the first experiment the glass eels were fed at a restricted feeding level and in the second experiment at an ad libitum feeding level. The intake of metabolizable energy (ME) was determined as the sum of retained energy and heat production. Metabolizability of the diets decreased with increasing feeding level and was 75-95% for cod roe, 35-50% for spleen and 40-60% for the artificial diets. Since utilization of ME for maintenance and growth was not affected by feeding level and diet, differences in growth rates could be explained by differences in ME intake. Group ME intake in turn was determined by the fraction of the fish which were actually eating. The uniform feeding response of the glass eels fed the natural diets resulted in the highest ad libitum ME intake (80-90 kJ/kg0.8/day) and growth rate (4-4-4-9g/kg0.8/day). Addition of feeding stimulants significantly increased the ad libitum ME intake of the artificial diets from 45 kJ/kg0.8/day to 50-60 kJ/kg0.8/day, which resulted in an increase in growth rate from 1·3 g/kg0.8/day to 24 g/kg0.8/day. |
| |
| Keywords: | |
|
|
