Exploring baseline behaviour in group-housed, pre-weaned dairy calves

With increasing public concern for farm animal welfare, understanding their current welfare status is paramount. Animal welfare can be inferred from their behaviour, as behaviour represents the combination of internal and external cues. The aims of this study were to quantify a behavioural baseline for group-housed, pre-weaned dairy calves that were reared under conventional management conditions, and to determine how different internal (i.e. age) and external (i.e. temperature) factors affected this behaviour. Female dairy calves (n=47) were allocated to 1 of 3 pens based on birth date and reared under conventional Irish management conditions; after 3–4 d in individual pens, calves were moved into group pens where they had ad libitum access to water, concentrates, and forage (first barley straw, then hay). Milk replacer (6 L/d) was fed through an automatic milk feeder; calves were gradually weaned from day 42–84. A 24 h period/week of video recording was used for behaviour scoring for 8 consecutive weeks (scan sampling at 10-min intervals). Behaviours included posture (lying or standing) and activity (17 behaviours). Calves were scored for clinical health twice weekly and only healthy calves were used in the analysis (n=39). Behaviour proportions were analysed using generalised linear mixed models. Proportion of time spent lying decreased as calves aged (week 1 vs. 9; percentage mean ± standard deviation; 79.8 ± 4.04 vs. 72.1 ± 6.52 %; P=0.004), while time spent ruminating (2.0 ± 2.51 vs. 14.1 ± 8.72 %; P<0.001), eating bedding (0.8 ± 1.16 vs. 6.1 ± 4.66 %; P<0.001), eating forage (0.9 ± 1.20 vs. 1.8 ± 1.81 %; P=0.007), and eating concentrates (0.5 ± 1.15 vs. 2.2 ± 1.72 %; P=0.018) increased with age. On days when the minimum shed temperature was <4°C compared to >6°C, calves spent more time lying (75.9 ± 5.27 vs. 72.3 ± 5.78 %; P<0.001) and less time eating concentrates (0.8 ± 1.11 vs. 1.4 ± 1.49 %; P=0.035), eating forage (0.8 ± 0.91 vs. 1.5 ± 1.57 %; P=0.005), eating bedding (2.7 ± 2.87 vs. 4.0 ± 4.78 %; P=0.003), and walking (1.5 ± 1.20 vs. 2.0 ± 1.40 %; P=0.017), independent of age. These findings provide a normal behaviour baseline for future calf behaviour studies and highlight potential areas of improvement in current, conventional calf rearing practices.