Comparative stereological study of the digestive tract of **Artemia franciscana** nauplii fed with yeasts differing in cell wall composition
Gunasekara, R.A.Y.S. Asanka
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences. Veterinary Sciences
Aquaculture. - Amsterdam
, p. 64-69
Different yeast strains are considered as best alternative feeds for rearing brine shrimp, Artemia franciscana, nauplii. The feeding effects of Saccharomyces cerevisiae (Baker's yeast) wild type strain and mnn9 mutant strain were investigated by stereological tools using the gnotobiotic Artemia rearing system as model. Gnotobiotic A. franciscana nauplii were fed daily with dead Aeromonas hydrophila, LVS3, and either wild type baker's yeast or mutant strain mnn9, of which the cell wall contains elevated chitin and glucan and lower mannose levels. Mean survival percentages, individual length, total length, volume and surface area of the digestive tract segments in relation to the individual length were compared between both groups of nauplii at 2, 4 and 6 days after hatching. The ratios between midgut length and individual length, between midgut volume and individual length and between midgut surface area and individual length for mnn9 yeast fed group and further wild type yeast fed group at day 6 were respectively 0.82 ± 0.01 and 0.76 ± 0.01, 4335.0 ± 72.1 and 2130.5 ± 211.4 μm2, 1641.9 ± 55.6 and 465.5 ± 56.1 μm which were significantly different between both groups (p < 0.05). Such clear differences were not observed for the ratios of hindgut segments. The results demonstrate better nutritional value of mnn9 yeast in comparison with wild type yeast. As far as we know, this is the first document which provides comprehensive data on the surface area of the various digestive tract segments in relation to the individual length of brine shrimp nauplii.