Try googling it, if i can remember properly, when i googled it they said a TINY amount of active yeast? that might have been for the daphnia though...this is a pointless comment isnt it haha.
Here;
To grow your brine shrimp onto adulthood, you must feed them. For the first 24 hours of life your brine shrimp will not require feeding as they are still relying on their egg sac, and have not fully developed their digestive system. Brine shrimp are non-selective filter feeders (meaning they're not fussy) and can be fed a wide range of foods, including but not limited to Liquidfry brand or similar fry food, yeast, whey, wheat flour, soybean powder, fish meal and egg yolk. The criteria for suitable foods is small, easily digestible particles which do not dissolve in water (for example, powdered milk won't work). Most importantly, do not over-feed them! In the small capacity of the soft drink bottle, it is very easy to foul up the water with excess feeding.