Relationship between immune response, liveweight gain, behaviour and adrenal function in red deer ( Cervus elaphus) calves derived from wild and farmed stock, maintained at two housing densities

Abstract

Immune response and other potential measures of stress were assessed in 40 weaned red deer calves in a 2×2 factorial experiment. Replicate groups of five calves (approximately 3 months of age) born to dams from two sources (wild, (W) or farmed, (F)) were housed at weaning at one of two stocking densities (1.8 m 2 per head, (H), or 4.5 m 2 per head, (L)) for 22 weeks. Calves were immunised with ovalbumin (OVA) 1 week after weaning and housing (Week 1) and again at Week 20. The initial (Week 2) lymphocyte response to OVA was lower ( P<0.05) in W than F calves. Antibody titres to OVA were lower ( P<0.05) in W than F calves at Weeks 4, 12 and 22. Antibody and lymphocyte responses to OVA showed that W calves were less able to mount and maintain an immune defence to a foreign antigen than F calves. Proportionally more time was spent lying inactive ( P<0.01) and less time feeding by W than F calves ( P<0.01). More time was spent standing by H than L calves ( P<0.01). Antibody titres were negatively correlated with liveweight gain ( r=−0.77; P<0.001), lying ( r=−0.31; P<0.01) and plasma cortisol concentration ( r=−0.46; P<0.001). Lymphocyte counts to OVA were correlated with liveweight gain ( r=−0.69; P<0.001). Activity and immune responses were identified as indices of housing stressors in weaned red deer calves. Measurement of primary and secondary antibody responses may be valuable in assessing the short- and long-term effects of housing density.