This work was undertaken to study the performance of lactating Holstein BW cows through milk yield, when submitted to two treatments, which consisted of their exposure to shade and no shade during the hotest hours of summer days. After a 55 days period, a clear tendency was evident for those cows on the no shade group to show a lower yield and, among those, the higher yielding ones were the most affected. According to our data it was concluded that shade has to be provided to lactating dairy cows, specially for higher producers, at the hotest hours of the day during summer months.
milk yields; shade and no shade management; summer milk production
