Preweaning dairy calves' preferences for outdoor access.

Abstract

Adult dairy cattle show a preference for outdoor spaces during summer nights, but little is known about such preferences for dairy calves. Our aim was to determine the preferences of dairy calves for outdoor access during their first 11 wk of age in summer conditions. Calves were paired (n = 10) at 7 d of age and placed in one of 10 pens (7.32 × 2.44 m, deep bedded with bark mulch), each with equally sized outdoor and indoor areas. All feed was provided indoors; calves had ad libitum access to water, hay and concentrate. During the preweaning period, from 5 to 29 d of age, calves were offered 12 L/d of milk divided into 2 feedings. Calves were weaned stepwise, with milk gradually reduced by 1 L/d from d 30 to 35 of age. Calves were fed 6 L/d from 35 to 51 d of age, then milk was again reduced by 1 L/d so that calves were completely weaned by 56 d of age. Calves remained in the trial until, on average (± SD), 72 ± 2 d of age. Pens were continuously video recorded, and behaviors were scored 3 d/wk using 5-min scan samples. Four observers scored whether calves were inside, outside, lying, standing, in the sun or shade (interobserver reliability = 0.97). Sun and shade could not always be detected, so a proportion was calculated as the amount of time in the sun or shade divided by the total time sun or shade was visible. Calves spent approximately one-third of their time outside throughout the experiment, and time spent outside was affected by several factors. Pairs of calves spent less time outside as the amount of rain increased. During the first 6 wk of age, time spent outside increased, but time spent outside decreased between wk 6 and 7, and remained around 200 min/d from wk 7 to 11. Calves with the highest average daily gain and calves that were approximately 50% white appeared to spend more time outdoors. When outside, calves spent similar amounts of time in the sun and shade during the first 8 wk, but after weaning they appeared to spend more time in the shade. When calves were outside they appeared to spend a greater proportion of their time standing than when they were indoors during the first 4 wk. These results indicate that, when given the option in the summer, calves make use of an outdoor space, but this appears to vary with weather, calf age, average daily gain, and coat color.