You can give Equilin Immuno for resistance support.

Equilin Immuno contains magnesium, vitamin E, MSM, vegetable omega 3 fatty acids, essential amino acids, pre- and probiotics and mycotoxin binder, among other ingredients. 

Equilin Immuno also has a number of additional additives, including milk thistle and nettle. You can use Equilin Immuno for 6 to 8 weeks in a row, because of the efficacy of the herbs. 

It can be given in addition to any ration and you can also feed it as a cure in the fall.