Abstract
Endothermic animals have to keep their body temperature (Tb) within a narrow limit with changing environmental conditions. There are indications that some wild ungulates can exhibit certain forms of energy saving mechanisms when ambient temperatures (Ta) are low and/or food availability is scarce. Therefore, the aim of the study was to determine if the llama, one of the most extensively kept domestic livestock species, exhibits seasonal adjustment mechanisms in terms of energy expenditure, Tb and locomotion under Central European climatic conditions. Methods: For that purpose 7 female adult non-pregnant llamas were kept under semi-natural conditions. Locomotor activity (LA) and Tb (measured in the rumen) were recorded continuously for each animal every 3min, the location and Ta every 30min for one year using a telemetry system. Daily energy expenditure was measured as field metabolic rate (FMR) during the European spring, summer, autumn and winter using the doubly-labelled-water method. Results: FMR fluctuated considerably between seasons with the lowest values found in winter (17.45±3.98 MJ/d) and the highest in summer (25.53±3.88 MJ/d). Similarly, the daily Tb amplitude was highest in summer and lowest in winter, with daily maximum and minimum Tb’s occurring around midday and early morning, respectively. Average daily Tb followed the Ta pattern throughout the year (r=0.78,P<0.001). Daily distances covered were correlated with LA (r=0.75,P<0.001). Comparing the two most extreme seasons in terms of Ta, i.e. summer and winter, animals had on average significantly higher (P<0.001) Tb and LA in summer (Tb=38.7±0.13°C,LA=8129±847 impulses) then in winter (Tb=37.6±0.13°C,LA=5392±895 impulses). Conclusions: The results show that llamas adjust their energy expenditure, Tb and LA according to season and time of the day. Thus, llamas seem to have maintained the ability to reduce their energy expenditure and adjust their Tb under adverse environmental conditions as has been reported for some wild ungulates