Growth, behaviour, adrenal and immune responses of finishing beef heifers housed on slatted floors at 1.5, 2.0, 2.5 or 3.0 m2 space allowance

Overcrowding of housed cattle can be detrimental to animal performance and welfare. The objective of this study was to measure the production, behaviour, adrenal and immune responses of finishing beef heifers at four space allowances on slatted floors. Simmental crossbred heifers (n = 96; 468 (s.e. 3.2) kg initial bodyweight) were assigned to treatments of 1.5, 2.0, 2.5 or 3.0 m(2) average individual space allowance, with three pens of eight heifers per treatment, for 140 days. On days 13, 69 and 132, heifers (9 per treatment) were challenged with 1.98 i.u. adrenocorticotrophic hormone (ACTH)/kg bodyweight(0.75) and blood samples were collected for cortisol determination. All other heifers (15 per treatment) were immunised against keyhole limpet haemocyanin (KLH) on day 84. Behavioural observations of all animals were conducted to record lying, eating and ruminating times, and aggressive and social behaviour. Heifers at the 1.5 m(2) space allowance had lower (P < 0.01) average daily gains than heifers at 2.0, 2.5 and 3.0 m(2) space allowances (0.52, 0.65, 0.70 and 0.69 (pooled s.e. 0.031) kg, respectively). Daily lying time was reduced (P < 0.001) for heifers at 1.5 m(2) compared with 2.0, 2.5 and 3.0 m(2) space allowances (10.3, 11.8, 12.0 and 11.7 (pooled s.e. 0.26) h, respectively). There were no effects of treatment on aggressive or social behaviour, basal or ACTH-induced cortisol and anti-KLH IgG(1) or IgG(2) antibody responses. It was concluded that the 1.5-m(2) space allowance was detrimental to animal growth and comfort compared with the other three space allowances. (C) 1997 Elsevier Science B.V.