BoSe is used for the prevention and treatment of White Muscle Disease in calves which is caused by a deficiency of Selenium. I don't know what you mean by "weak joints" but BoSe has no effect on bones. BoSe has 1 mg per cc of Selenium from sodium selenite and 50 mg of vitamin E. Vitamin E and Selenium work synergistically in the calf. Dosage is 2.5 to 3.75 cc per one hundred pounds bodyweight in calves. MultiMin, on the other hand contains Zinc, Manganese and Copper, in addition to Selenium. Each cc of MultiMin 90 contains 5 mg of Selenium from sodium selenite and the dosage is 1 cc per 100 pounds of bodyweight up to 1 year of age. Therefore, a therapeutic dose of BoSe will contain up to 3.75 mg Selenium and a therapeutic dose of MultiMin contains 5 mg Selenium per one hundred pounds of bodyweight. The difference in value between the two comes in situations where you might be deficient in Zinc, Manganese or Copper, in which, MultiMin will be the therapy of choice, rather than BoSe. MultiMin will be more painful locally for the calf if it is not administered properly.