Introduction
During recent years, animal welfare has become an important issue among scientists as well as the general public. Much of the discussions have concerned the housing of our animals and different types of management systems (e.g. Friend & Dellmeier 1987; Ladewig & Smidt 1989; Müller et al. 1989; Kapp et al. 1997). The purpose of this study was to investigate how Swedish domestic goats (Capra hircus) reacted to being kept together in pairs with space to move around vs. being tied up individually in metabolism cages, and how this affected their heart rate, arterial blood pressure and cortisol concentration.
Methods
Eight non-pregnant, non-lactating goats were used and six of the goats had implanted transmitters (Hydbring et al. 1997) that registered heart rate and arterial blood pressure telemetrically. The animals were randomly divided into two groups and the experiment was performed in a change-over design. The goats were either kept in a big pen with another goat or tied up individually in metabolism cages. The animals were fed hay and concentrates at 07.00 and 15.00h. Before the registrations started, the animals were housed in the new system for four days. Thereafter, telemetry registrations were made every 30th minute during 24 hours. Since we did not want to disturb the animals with blood sampling during the telemetric registrations, blood samples were taken the next day by venipuncture at 08.00, 10.00, 12.00, 14.00 and 16.00h.
Results
Heart rate rose around the morning and afternoon feedings, whereas blood pressure did not show any clear diurnal rhythm. Comparison between the different management systems revealed that heart rate, systolic-, mean-, and diastolic blood pressure values were significantly higher when the goats were tied up. The cortisol concentration also tended to be higher when the goats were tied up (NS)
Conclusions
It is well known that physical activity increases heart rate, blood pressure and cortisol concentration. Goats that were kept two and two had more space and were more active yet, despite this, they still had lower levels of the measured variables. This indicates that group housing offers less strain on the cardiovascular system and thus should be better for the animal. The higher values when tied up suggest that the goats were psychologically affected by this system. This was supported by the observation that some of the animals seemed to be frustrated over being tied up and pulled back in the chain, and sometimes had difficulties to lie down. Our results emphasise the importance of further studies on different management systems to clarify how they may affect experimental planning and evaluation of results.
References
Friend, T. & Dellmeier, G. 1987. J Dairy Sci 70, 1595-1600
Hydbring, E., MacDonald, E. & Olsson, K. 1997. Acta Physiol Scand 161, 295-302
Kapp, G., Friend, T., Knabe, D., Bushong, D. & Lay, D. 1997. Contemp Top 36, 61-65
Ladewig, J. & Smidt, D. 1989. Horm Behav 23, 344-360
Müller, C., Ladewig, J., Thielscher, H. & Smidt, D. 1989. Physiol Behav 46, 751-754