Effects of shade provision on the behaviour, body temperature and milk production of grazing dairy cows during a New Zealand summer

Abstract

The aim of this study was to quantify the behavioural use of shade during a New Zealand summer, and to determine the effects of shade availability on body temperature and milk production. Holstein‐Friesian cows were either grazed with access to shade, or grazed in an adjoining part of the field with no shade, for two 10‐day periods in a cross‐over design with 10 cows per treatment. Vaginal loggers recorded body temperature and video cameras recorded shade use. Cows started to use the shade when the temperature reached 25°C and shade use increased exponentially with increasing ambient temperature. Data analysis for behaviour and body temperature was restricted to 6 days on which the maximum temperature was ≥25°C. Milk production data were analysed across the entire experiment of 20 days. Despite cows spending 80 min per day in the shade, there were no differences between shaded and unshaded cows in grazing time per 24 h. Shaded cows had lower peak and mean body temperatures during the day than unshaded cows, but there was no difference in mean 24‐h body temperature. Milk production was 3% greater for shaded cows than for unshaded cows. These results indicate that even during temperate summer conditions, dairy cows will use shade and that this has benefit in reducing body temperature during the warmest parts of the day.

Keywords:

• behaviour
• body temperature
• dairy cows
• milk production
• shade