In an experiment on nine Kumaoni bullocks, the effect of supplementing paddy straw rations with calcium carbonate or lime was studied. The digestion coefficients of dry matter, crude protein, ether extract and total carbohydrates and balances of nitrogen and phosphorus were not significantly affected by such supplementation; the calcium balances were significantly improved. It is concluded that supplementation of paddy straw rations with calcium carbonate (which is cheap and easier to handle), or with slaked lime, can be used with advantage in combating the problem of negative calcium balances frequently encountered on paddy straw rations. Incorporation of a small quantity of wheat bran (about 4 oz) helps in meeting the phosphorus requirement of adult animals.