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Ten cows in early stages of lactation (less than 100 days postpartum) were used to test the effect of sprinkler/fan cooling on vaginal temperature patterns. Cows were assigned to two groups matched according to milk production. The trial was divided into three periods: period 1, when one group was treated and the other group was not, period 2, when neither group was treated, and period 3, when treatment was switched from period 1 between groups. Treatment consisted of forced air misting in a premilking holding pen, fan cooling during milking, and forced air-sprinkling in a postmilking holding area. Weather conditions were measured by dry bulb, wet bulb, and black globe temperatures. Black globe temperatures in pre- and postmilking holding areas were used to estimate treatment magnitude. All measures were obtained through radiotelemetry at 15-min intervals for 31 days. Animals were milked twice a day. Animals spent an average of 140 min in treatment at each milking. In both morning and afternoon milking, treatment caused a transient increase of body temperature. However, this was followed in the afternoon by low vaginal temperatures for 1 to 2 h beyond treatment with lower temperatures throughout the day.

Vaginal temperature patterns were obtained from 15 Holstein cows through radiotelemetry. Animals were divided into three groups with five animals per group: 1) cows in early lactation, less than 100 days postpartum, 2) cows in late lactation, greater than 240 days postpartum, and 3) dry cows. Animal temperatures, dry bulb, wet bulb, and black globe temperatures were monitored every 15 min for 17 days. Analysis of variance showed no significant difference for daily mean vaginal temperature between lactation groups. However, on hotter days, lactating cows had higher temperatures than dry cows. Daily mean vaginal temperatures of cows in early lactation were correlated with daily mean dry bulb temperature, black globe temperature, and relative humidity. Comparison of group temperature patterns isolated differences to specific times of day. In groups with early and late lactations, temperatures were lower in either group after milking. Vaginal temperatures were higher in lactating cows than in dry cows through most of the day. Results were 1) diurnal temperature patterns differ among groups; 2) lactating cows are sensitive to environmental changes; and 3) animal management can affect patterns of animal temperature.