A method for prophylactic treatment of ketosis in a calving cow, the method including orally administering to the cow within a time period of about 12 hours after calving an effective dose of from 20 to 30 g of rumen protected methionine. If the cow falls into a risk category, the cow is administered the dose of rumen protected methionine once a day on the second, third, fourth, and fifth days after calving. Also, a composition including a gelatin capsule and rumen-protected methionine contained within the gelatin capsule that may be administered to a calving cow for the prophylactic treatment of ketosis. The composition may further contain within the gelatin capsule one or more other compounds known to have efficacy on fat or glucose metabolism, such as glucose, propylene glycol, niacin, choline, chromium, calcium propionate, and glucocorticoids.