The effects of tunnel ventilation cooling and brown mid-rib (BMR) corn silage on symptoms of heat stress in lactating dairy cows

The potentials for tunnel ventilation cooling and brown mid-rib (BMR) corn silage to alleviate heat stress were studied in four groups of 10 mid-lactation Holstein cows. Two groups were housed inside a tunnel ventilation barn while the remaining groups were housed in an adjacent outside freestall barn cooled with fans and sprinklers. One group in each barn received a diet based on BMR corn silage while the remaining group was fed a diet based on a typically used corn silage variety. Milk production for the inside group fed the BMR silage averaged 3.36 +/- 0.47 kg greater (P < 0.0001) than the inside group fed the control silage and 2.55 +/- 0.46 kg greater (P < 0.0001) for the outside group fed the BMR silage. The tunnel ventilation barn averaged 6.2°C less and the average exposure time to moderate heat stress (temperature-humidity index between 80 and 90) was reduced 7.27 h/d compared to cows housed outside. Thus, under these conditions, tunnel ventilation cooling was comparable to traditional cooling methods for reducing the severity of heat stress in dairy cows in the southeastern U.S. (Abstract shortened by UMI.)...