The effects of zinc-enriched Saccharomyces cerevisiae on the growth and mineral composition of marine rotifer, Brachionus plicatilis

Rotifers are important zooplankton in commercial finfish hatcheries. However, due to the limited variety of food available, zinc content of cultured rotifers in artificial environments may not meet the requirements of fish larval. It has been reported that direct addition of soluble zinc to culture media was not effective on the zinc content of rotifer. Thus, in this study, the effect of zinc-enriched Saccharomyces cerevisiae was investigated on the growth and mineral composition of rotifer, Brachionus plicatilis. Four different food treatments, including (1) yeast without enrichment (control), (2) yeast containing 21.23 mg g-1 of zinc, (3) yeast containing 56.25 mg g-1 of zinc, and (4) yeast containing 132.93 mg g-1 of zinc, were used to produce rotifer for a period of 10 days. Afterwards, specific growth rate (SGR), the total number of rotifers, total eggs attached to rotifers, and the total number of eggs were measured. Finally, the mineral composition of rotifer in different treatments was analyzed. The findings revealed that yeast enriched with 56.25 mg g-1 of zinc significantly improved the growth of rotifers. The maximum number of rotifers (274 ind ml-1), total eggs attached to rotifers (29.3 number ml-1), and the total number of eggs (36 number ml-1) were found in the third treatment. The highest zinc content was observed in the fourth treatment (about 822.5 μg g-1 of rotifers). The maximum values of Fe (13.84 μg g-1 of rotifers) and Mn (15.22 μg g-1 of rotifer) were related to the treatment 4 and control, respectively. However, the amount of Cu did not significantly differ among the treatments. In conclusion, this study found that zinc-enriched yeast improved the growth, reproduction, and body composition of B. plicatilis.