Do dairy cattle use a woodchip bedded area to rest on when managed on pasture in summer?

Previous studies have demonstrated that dairy cattle prefer pasture over indoor conditions especially at nighttime, which suggests they perceive pasture as an attractive place to rest. Indeed, cows avoid and spend less time lying on hard surfaces, such as concrete or mattresses, compared to softer surfaces. This study aimed to investigate how much time cows spend lying on pasture at the end of summer when the ground can be hard, compared to a softer surface. Four groups of lactating dairy cattle (5 cows/group) had access to either pasture alone or a pasture containing two deep bedded woodchip areas for 9 consecutive days in a cross-over design. Woodchip usage and posture (upright or lying) were recorded using data loggers and video cameras. We also recorded weather conditions, surface characteristics (hardness, dry matter content, temperature) and milk production. There were no consistent significant differences in lying times of cows with or without woodchip bedded areas. Average lying times for groups with access to pasture only and the woodchip were 8.9 h/24 h (range: 7.8–10.1 h) and 8.5 h/24 h (range: 7.6–9.7 h), respectively, excluding milking times. Average number of hours per day on the woodchip was 2.1 h (range: 0–5.9 h), however, there was considerable animal variation in the use of the woodchip bedded areas. When cows were on the woodchip, they spent on average 51 % of their time lying (SEM: 7 %) and when they were on pasture they spent 36 % of the time lying (SEM: 1 %). Most of the lying, however, was on the grass. Both surfaces likely provided cows with a comfortable lying surface despite pasture being harder than the woodchip. Rainfall prior to data collection may have contributed to pasture being unusually soft for the time of year. Overall, lying times decreased with increasing heat load (air temperature, temperature-humidity index, heat load index, P < 0.001) and rainfall (P = 0.002). Cows spent less time on the grass and more time on the woodchip as the daily average air temperature increased; for each 1 °C increase in air temperature, the time spent on grass decreased by 1.0 ± 0.46 (SE) percentage points per day (P = 0.047). We speculate that this was due to woodchip being a cooler surface or attracting fewer flies than the grass. In conclusion, cows varied in their use of deep bedded woodchip areas when provided in the pasture, however, most of the time spent lying was on the grass.