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738
Economic value of cooling dry cows across the United States
Heat stress during the dry period reduces milk yield in the next lactation. Our objectives were to quantify the economic losses due to heat stress of dry cows and to evaluate investment in cooling of dry cows. We used weather data from NOAA to quantify the average amount of heat stress for the 48 contiguous US states. A heat stress day was declared when the average daily temperature humidity index was ≥ 68. A spreadsheet was developed for economic analyses. Assumptions were that 15% of the cows were dry at any time, the dry period length was 46 d, and only cows in parities ≥ 2 increased milk yield if cooled in the dry period. Milk yield decreased by 0.11 kg/d in the next lactation (305 d) per heat stress day in the dry period based on a review of the literature. Marginal decrease in dry matter intake was 0.4 kg per 1 kg less milk. Marginal value of milk minus feed cost was $0.33/kg. Economic analysis included investment in fans and soakers, and use of water and electricity. Building investment was considered separately at a price of $2,500 per stall. On average, a US dairy cow is under heat stress 96 d during the year and loses 271 kg of milk in the subsequent lactation if not cooled when dry. Weighted by the number of cows in each state, annual losses would be $820 million if dry cows were not cooled ($89/cow per year). For the top 3 milk producing states (CA, WI, NY) and FL the average milk loss in the next lactation was 316, 212, 234 and 726 kg and profit loss/cow per year were $104, $70, $77 and $238, respectively. The average benefit-cost ratio of cooling dry cows in the US is 2.46 (dry cow building already present) and 1.59 (including building a dry cow barn) in the baseline scenario. For positive net present values, 18 d and 27 d are necessary when a building is not built (considering marginal milk prices of $0.33 and $0.22, respectively). If a barn is built, minimum days of heat stress would be 47 and 69, respectively. Other benefits of dry cow cooling, such as increased health and more productive offspring were not considered. In conclusion, cooling of dry cows was profitable in all 48 states and very profitable in most states.
Keywords: dry cows, economics, heat stress, THI