The rotifer populations (L-type) originating from the Ori-One and the Ori-Green enrichment were sieved in different size classes to separate the new-born rotifers (neonates)from the adults.The setwo differ-ent populations had a body length of 132 ± 20 μ and 192 ± 28 μ for
neonates and adults respectively. The HUFA content of the neonates and adults was identical for the Ori-one treatment (30 ± 2 mg·g−1DW) whereas in the Ori-Green treatment the HUFA concentration of the neonates was only 15 mg·g−1 DW and 50% of the concentration of the adults. The difference in DHA levels for neonates harvested from the short term enrichment was 3 times lower than that from the ones originating from the stand-alone diet. Protein levels did not differ from one treatment to another but neonates contained on average 2% more protein than the adults