The cobolt in the wormer is only a small amount , you can buy co ,se,b12 ready mixed at your local supplier and you will need to drench every 2-3wks if you are deficient , would be better to have your vet take bloods and find if you have any deficiency before you drench , its been a bad year for cobolt . I think if you want them to eat hay you will have to bring them inside at least over night or they won't eat it if they have lots of grass Natural stockcare have 250ml containers