Supplementary effect of several nutrients on nutritive deficiency of baker's yeast for population growth of the rotifer Brachionus plicatilis.

Abstract

The culture of the sterilized rotifer Brachionus plicatilis with washed cells of a baker's yeast revealed that the yeast had no nutritive effect on the pupulation growth of the rotifer. Nutritive quality of experimental suspensions was evaluated by two kinds of culture, one of which was individual culture in which the rotifers were cultured separately in test tubes and observed daily to obtain the survival rate and fecundity while food suspension was renewed daily. From daily counts, intrinsic rate of population increase and net reproduction rate were calculated as the indices of nutritive quality of the suspension. The other was batch culture in which teh rotifers were maintained in the food suspension without any daily treatment. After 6 or 7 days culture, the increase in individual number was counted. Out of the nutrients tested on the supplementary effect, vitamin B12 was most effective. Pollack liver oil (feed oil) and cystine were also effective in strengthening the nutritive quality of the yeast cell suspension. None of the oil spluble vitamins could substitute for the supplementary role of the feed oil.