Inter- and intra-individual variation in resting behaviour in dairy cows
J. van der Werf, H. Hopster and H.J. Blokhuis
Department of Behaviour, Stress Physiology and Management, Institute for Animal Science and Health (ID-Lelystad), Lelystad, The Netherlands
Interpretation of lying behaviour of dairy cows in terms of welfare is difficult because reliable information on parameter values is lacking. This applies to information such as the variation between and within animals, changes in lying time and the relevance of it, the number of lying bouts, and the interaction between lying behaviour and management. It has been realized that these parameter values can only be reliably estimated by automated 24-hour recording. Therefore, a system has been developed at ID-Lelystad that enables continuous recording of lying behaviour of dairy cows.
In a free stall barn, 16 cubicles were equipped with commercially available electronic cow-identification receivers, supported by two photoelectric cells in each cubicle to identify the posture of cows. Around the neck cows were wearing transmitters, which had been slightly adjusted for use in this system. Cubicles were automatically scanned for transmitter number and photoelectrical output one after the other twice every minute, and data was stored in computer.
The system was validated by means of video observations (72H time-lapse mode), with a single camera overlooking 16 cubicles. After (automated) correction for double identifications by adjacent receivers in empty cubicles, 93.7% of the 4203 lying periods could be reliably recorded. Missing cow-identification (3%) was restricted to lying bouts of less than 5 min only. To study intra- and inter-individual variation in lying behaviour, 16 Holstein Friesian dairy cows (days in lactation: 156) were housed in the system for 6 weeks. After habituation, the last 19 days were used for the analysis. On average (19 days) cows spent 723 min/day (16 cows; s.d. between cows: 115) lying. Individual cow means (19 days) ranged between 483 and 985 min/day. Lowest and highest standard deviations within cows were 44.6 and 97.6 min/day. Corresponding values for the number of lying bouts were 12.1 (± 2.37); cow means ranged 7.7-16.4 and standard deviations within cows ranged 1.12-2.49.
The large differences between cows together with the low standard deviation within cows suggest that lying behaviour (time and bouts) is consistent over time and characteristic for the individual cow.
Poster presented at Measuring Behavior 2000, 3rd International Conference on Methods and Techniques in Behavioral Research, 15-18 August 2000, Nijmegen, The Netherlands