The effects of providing shade to lactating dairy cows in a temperate climate

Abstract

Abstract In a two-period replicated crossover design, four groups of lactating Holstein Friesian dairy cows ( n = 10 per group) were kept on pasture to investigate the effects of providing artificial shade in summer on their vaginal temperature, behaviour and milk production. Two groups had access to shade and two groups in adjacent paddocks had no shade for a 10-day period before the treatments were switched. The body temperature rhythm was recorded in all animals using vaginal data loggers. Daily milk yield and milk composition was measured for each cow. Standing without grazing, lying and grazing behaviour was recorded continuously by observers for two 24-h periods during each 10-day treatment period. Shade use was recorded daily from 0800 to 2000 h. The provision of shade reduced ( P P P > 0.05) on the maximum and minimum vaginal temperature, or the amplitude of the vaginal temperature rhythm was found. Cows with access to shade preferred ( P P P > 0.05) between treatments. Milk production was higher ( P P > 0.05) by shade treatment. These data suggest that the provision of shade is an effective method to reduce heat load in dairy cows under New Zealand summer conditions and, in addition, may increase daily milk yield. Despite only mild summer conditions, vaginal temperature was elevated during the mid-afternoon in non-shaded cows but did not cause a significant disruption in the underlying circadian body temperature rhythm compared to shaded cows.