the only uses ive found on castor oil and chickens are:
and scaly legs
and this one:
Purge birds with castor oil (2 tsp.) followed by a stimulating tonic
of powdered fennel, anise, coriander, and cinchona (30 grains
each). Give powdered gentian and ginger (1 dram each).
Give powdered sulfate of iron (15 grains); mix and add to feed.
Hepar sulph or Nat Mur