Space requirements of breeding heifers - housing and animal welfare aspects

The purpose of the present study was to investigate the influence of crowding on the performance of breeding heifers. In either of two experiments 64 heifers were kept in groups of eight on slatted floor or staw under crowded and non crowded conditions. Crowding stress could touch economical questions as well as animal welfare problems. The results obtained may be summarized as follows: 1. Resting behaviour was particularly disturbed on slatted floor as shown by a significant reduction of periods of lying down as well as disturbed or altered laying down behaviour. 2. The periods of simultaneous Tying down of a whole group were reduced under crowded conditions. 3. The depression of social activities was signicant on slatted floor. 4. The growth rate was reduced by 20 % in the groups on slatted floor with 1,6 m(2) per animal. 5. Crowding reduced the fertility rate by 13 %. 6. The heart rate during laying down themselves was tendentially elevated in heifers kept on slatted floor. 7. The cortisol concentration during and after laying down themselves increased continuously in animals kept on slatted floor, whereas a declining tendency in cortisol concentration was observed in animals kept on straw. 8. Frequency and mean amplitude of basal cortisol secretion were reduced. 9. The adrenal response was significantly lower under crowded conditions on slatted floor. 10. Previously stressed animals had a significant higher adrenal response after three weeks of pasture conditions as compared to unstressed heifers.