Changes in behaviour, cortisol and lymphocyte types during isolation and group confinement of sheep

Abstract

SummaryThis experiment compared changes in complex behaviour patterns, adrenal corticosteroid secretion and the numbers of various types of lymphocytes in sheep that were subjected to the stress of confinement. Grazing Merino ewes (n = 80 in five replicated experiments) were confined either in groups of four per pen or in total isolation from other sheep. The percentage of CD4 + lymphocytes increased while the percentage of CD8 + lymphocytes decreased over the experimental period. This result was more pronounced in isolated sheep than in grouped sheep. The increase in CD4:CD8 was greater for isolated sheep than for grouped sheep and greater for 2 week sheep than for 3 week sheep. The percentage of CD5 + cells also increased, less so in isolated than in grouped animals. Interpreting these changes as a recovery of immune competence following introduction of a stressor, it is apparent that isolation impaired immune system recovery more severely than group confinement. Physiological and behavioural adaptation over the period were characterized by a decline in the adrenocortical response, resumption of the normal pattern of flocking behaviour and a reduction in motor activity during the test. These findings add to the evidence pointing to the possible correspondence between critical features of the psychoneural, neuroendocrine and immune systems.

Effect of pre-weaning concentrate supplementation on peripheral distribution of leukocytes, functional activity of neutrophils, acute phase protein and behavioural responses of abruptly weaned and housed beef calves

“…These findings suggest that offering concentrates may provide some level of immune protection, manifested as a lesser reduction in WC1+ (γδ T) cells and more stable αβ T cell population. An overall increase in CD4+: CD8+ ratio was reported by Degabriele and Fell (2001) [29] in sheep that were housed either in isolation or in groups. These authors attributed the rise in CD4+:CD8+ ratio to recovery of immune compensation following perturbation to lymphocyte subsets due to a stressful change in environment.…”

Effects of diets containing grape seed, linseed, or both on milk production traits, liver and kidney activities, and immunity of lactating dairy ewes

“…Group feeding of the forages was chosen to avoid the inevitable stress caused by individual confinement of lactating ewes in this long-term study (10 wk in total), whose goals were to evaluate production and immunological and hematological responses to feeds with high antioxidant activity. As individual confinement was reported to affect the immune system of sheep (Degabriele and Fell, 2001) and sheep are notoriously gregarious animals, in this experiment they were kept in groups to favor normal eating and social behaviors (Hutson, 2007).…”

Effect of abrupt weaning at housing on leukocyte distribution, functional activity of neutrophils, and acute phase protein response of beef calves

“…This increase may reflect recovery of immune competence in an attempt to restore homeostasis following the initial reaction to the onset of stress. An overall rise in CD4 + : CD8 + ratio was reported in sheep that were housed either in isolation or in groups [47]. These authors attributed the rise in CD4 + :CD8 + ratio to recovery of immune compensation following perturbation to lymphocyte subsets due to a stressful change in the environment.…”

“…Decreases in both peripheral CD4 + and CD8 + lymphocytes have been reported in calves at unloading after 14 h truck transportation, following which they returned to pre-transport values by 24 h [14], and in beef steers following induction into a feedlot environment [43]. Some studies examining the effect of stress in domestic animals have utilised the CD4 + : CD8 + ratio as an indicator of stress-induced immunosuppression, however conflicting evidence exists in cattle [44-47]. Our findings showed that movement of beef calves from a pasture environment to a housing environment was able to elicit a transient increase in CD4 + :CD8 + ratio.…”