PROTEIN AND LIPID-CONTENT OF THE ROTIFER BRACHIONUS-PLICATILIS DURINGVARIABLE GROWTH AND FEEDING CONDITION

Rotifers (Brachionus plicatilis) grown at different growth rate (mu = 0.05-0.39 d(-1)) were analyzed for protein, lipid, fatty acids, amino acids and free amino acids, and values are expressed in terms of indiv iduals and dry weight. Increase in growth rate is equivalent with incr eased food ration of the individual rotifer, which responded by higher egg ratio. The protein content per individual rotifer increased by 60 -80% when the growth rate increased, whereas the protein content per d ry weight showed a slight, although insignificant, increase (p>0.05). The lipid content per individual was constant, whereas lipid per dry w eight decreased when the growth rate increased. The ratio DHA/EPA decr eased when the growth rates increased. The amino acids profile in perc ent of total amino acids showed low variation between cultures maintai ned at different growth rates, whereas the values expressed in terms o f amino acid per individual showed higher variation. The range of vari ation for free amino acids was more pronounced than for total amino ac ids. Short-term food enrichment of poorly fed rotifers (mu = 0.05 d(-1 )) with balanced protein rich diet resulted in increased protein and l ipid content per rotifer. The protein content per dry weight showed on ly minor changes whereas lipid per dry weight increased. Contrary, sho rt term enrichment with a lipid rich diet resulted in increased lipid content per individual rotifer and per dry weight, whereas the protein content per individual remained constant and the protein content per dry weight showed a slight decrease. Our experiments show that the amo unt of protein, was quite variable in rotifers, and that feeding and g rowth condition were decisive factors affecting it. The range of varia tion was large enough to be an important factor during first feeding o f marine larvae, and should therefore be considered in feeding larvae.