High energetic costs of stereotyped behaviour in preruminant calves

High energetic costs for standing versus lying ( 130 kJ/kg0.75/d) in preruminant calves were mentioned in several experiments. Behaviour, and particularly stereotyped behaviour, can be an important reason for these high estimations. It was hypothesized that calves spend a considerable part of their time on stereotyped behaviour and that energetic costs of stereotyped behaviour are high. In this study (originally not designed to study behaviour) energy expenditure related to stereotyped behaviour was quantified in individually housed preruminant calves. Eighteen preruminant calves (on average 120 kg BW) were used, in two experimental periods of 9 days each. Heat production was measured by indirect calorimetry in 6-min intervals. Physical activity was recorded by a radar-Doppler device and posture was recorded by infrared beam interruption. Energy expenditure related to activity was estimated. Behavioural observations were made of each calf for two days per period, 13 hours per day, using 6-min scan-sampling. Five and 47% of the time spend standing and lying, respectively, was spent idling. Main activities during standing were manipulating bucket (37%) and (other) objects (24%), and tongue playing (10%). Main activities during lying were tongue playing (15%) and self-licking (8%). The sum of these repetitive activities, except self-licking, was considered total stereotyped behaviour. Stereotyped behaviour during standing increased energy expenditure almost threefold (+74 kJ/kg0.75/d) compared to standing idle (39 kJ/kg0.75/d), while tongue playing during lying was energetically more expensive (+25 kJ/kg0.75/d) than lying idle (1 kJ/kg0.75/d). It can be concluded, that energetic costs for stereotyped behaviour are considerable, and account for up to 8 (lying) and up to 15% (standing) of the energy expenditure for maintenance. As stereotyped behaviour is more frequently shown in standing as opposed to lying calves, this affects estimation of posture-related energy expenditure.