Calcium deficiency in high yielding bovines during calving causes “milk fever” which leads to economic losses of around ₹ 1,000 crores (US $ 137 million) per annum in Haryana, India. With increasing milk production, the risk of milk fever is continuously rising. In the context, we aim to address the most fundamental research question: What is the effect of a preventive health product (anionic mineral mixture (AMM)) on milk fever incidence, milk productivity and farmers’ income? In an effort to contribute to the scanty economic literature on effect of preventive measures on nutritional deficiency disorders in dairy animals, specifically, on AMM effects in India, this study uses a randomized controlled design to estimate internally valid estimates. Using data from 200 dairy farms, results indicate that milk fever incidence decreases from 21% at baseline to 2% in treated animals at follow-up. Further, AMM leads to a 12% and 38% increase in milk yield and farmer’s net income, respectively. Profits earned due to the prevention of milk fever [₹ 16,000 (US$ 218.7)] overweighs the losses from milk fever [₹ 4,000 (US$ 54.7)]; thus, prevention using AMM is better than cure.