Urination and defecation by group-housed dairy calves

A better understanding of when and where group-housed calves are most likely to defecate or urinate might permit improved housing design or more efficient use of cleaning routines. However, this is the first study to address the urination and defecation habits of calves. The primary aims of this study were to report the daily frequency of calves' urination and defecation and determine when and where group-housed dairy calves defecate and urinate most frequently. We were also interested to see if incidence of urination and defecation changed with increasing age and the change in diet at weaning. We observed 36 female Holstein calves, housed in groups of 9, and fed milk, grain, and hay from automated feeders. For the purposes of another experiment, these calves were assigned to 1 of 3 experimental treatments relating to age at start of weaning and milk allowance: low milk allowance and early weaning (6 L/d, 42 d), high milk allowance and early weaning (12 L/d, 42 d), and high milk allowance and late weaning (12 L/d, 84 d) The occurrence of defecations and urinations was determined by continuous observation of video recordings taken over 72 h at 2 age periods (age, mean ± SD; period 1=32.0 ± 11.13 d and period 2=61 ± 11.29 d). Due to the treatments, weaned and unweaned calves were observed in each period (period 1: 34 unweaned and 2 weaned calves; period 2: 16 unweaned and 20 weaned calves). Large differences were found between calves in mean daily frequency of total urinations and defecations across a 3-d period (mean=17.56 ± 5.07/d, range=4.33 to 28.67). Differences between individual calves did not change significantly over time, provided calves remained unweaned. Two days of observation was sufficient to give a reliable estimate of daily urination and defecation frequency. Frequency of urination and defecations was higher in calves postweaning. Higher age and visits to the milk feeder were associated with a higher frequency of urinations and defecations preweaning. After weaning, frequency of eliminations increased with increasing visits to the water feeder. An effect of time of day was observed, with significantly more events during daylight hours (0600-1800 h) in comparison to night (1800-0600 h). Before weaning, calves urinated and defecated significantly more on slatted flooring and sawdust-bedded areas than within the feeder (daily mean ± SD=6.96 ± 3.15, 6.49 ± 3.90, and 4.10 ± 2.67 for slatted floor, bedded floor, and feeder areas, respectively). Frequency of eliminations in feeders and slatted, but not sawdust-bedded, areas was higher in calves postweaning. Calves urinate and defecate more frequently during daylight hours when they are more active. Slatted flooring around feeders is useful to reduce soiling of bedded areas, particularly as calves increase in age.