Abstract: The present invention provides a calcium absorption enhancer that places no burden on the body of a human or a domestic animal to which a calcium compound is administered and can increase the efficiency with which a calcium content is absorbed into the body by supplying calcium ions in the stomach or the like of the human or the domestic animal in a sustained-release manner after administration of the calcium compound. The calcium absorption enhancer of the present invention contains, as an active ingredient, water-soluble calcium particles that can release calcium ions in an aqueous solution in a sustained-release manner.

Abstract: The present invention provides a method of culturing zooplankton that allows solids serving as feed for zooplankton to remain in a culture medium, while preventing accumulation of growth inhibitors of zooplankton and growth of bacteria, and an apparatus for culturing by the same. The culture method of the present invention includes removing a growth inhibitor of the zooplankton and/or a water-soluble nutrient for bacteria from a culture medium containing the zooplankton by a solid/liquid separation membrane with perfusion. The culture method of the present invention can produce a culture for use as feed for fishes or crustaceans containing at least 50,000 per ml of highly lively zooplanktons.