Spray Cooling Effects on Milk Production, Milk, and Rectal Temperatures of Cows During a Moderate Temperate Summer Season

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Abstract
During summer 1982, responses of lactating Holstein and Guernsey cows were measured by milk temperature recorded by a Digital Dataloger with thermocouples attached to Boumatic flow meters. Maximum air temperature and temperature-humidity index averaged 30.8.degree. C and 75.6 for July. Breed did not affect milk temperature, but within-breed milk temperature increased with production. In a 2nd study, benefits of spray cooling were evaluted with 24 Holsteins in midlactation assigned randomly to 2 groups of 12 and maintained under loose-housing conditions. Spray nozzles were installed in the walkways and under the manger shade for the spray treatment group. Maximum temperature and temperature-humidity index during the spray study were 27.degree. C and 73.9. Rectal temperature taken following milking averaged less for treatment than control (38.8 vs. 39.1.degree. C). Milk temperature was similar (37.8 vs. 38.1.degree. C). Daily milk yield was .70 kg higher than controls. Milk temperature probably provided reliable indication of climate stress similar to rectal temperature, and spray cooling improved cow comfort and lessened summer decline of milk production.
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