Here is what I do:

1. Break off a chunk of frozen mysis put in a cup and thaw.  I put mine in the microwave on very low setting for 20 to 25 seconds.  Do not do this for too long or you will destroy the nutrients.
2. Put the chunk into a fine mesh strainer (available at your local housewares shop) and rinse thoroughly with RO or distilled water.  Do not use tap water as it contains chlorine and/or chloramines which can poison your horses, and will breakdown the nutrients in the mysis.
3. Shake them dry and return to the mixing cup.  Drain off any remaining water either by pouring it out or using a paper towel to blot them dry.
4. Now, add the enrichment.  Approximately 1/10 of a teaspoon per 20-40 shrimp is a good amount.  Mush it around for 30 seconds to be sure it is embedded properly.  Do not damage the shrimp by mushing too hard!
5. Feed to the horses.

You will notice that the shrimp are relatively dry when you enrich, which makes the enrichment medium really stick, which will be evident by the lack or reduction of effluent in the water when you feed.

To further increase the stickiness of the enrichment, you can leave the enriched mysis in the refrigerator overnight.  This will dry the enrichment slightly and harden it, encrusting the mysis in the enrichment medium.

Mysis shrimp enriched this way will generally last in the refrigerator for approximately 48 hours.