Cortisol and β-endorphin responses to physical and psychological stressors in lambs

Abstract

. 1997. Cortisol and ␤-endorphin responses to physical and psychological stressors in lambs. Can. J. Anim. Sci. 77: 689-694. Plasma cortisol, β-endorphin, T3 and T4 were determined in lambs before, during and after exposure to stress in order to evaluate the potential use of these hormones to objectively measure stress responses. Lambs were exposed to tail-docking, castration, weaning, isolation, and restraint stress. Twelve ewe and 24 ram lambs were assigned to the experiment, with 12 of the ram lambs surgically castrated when 3-wk old. Tail docking within 24 h of birth did not (P > 0.05) elevate either plasma cortisol or β-endorphin. Castration markedly elevated (P < 0.001) plasma cortisol and β-endorphin within 15 min of surgery. Both hormones were highly elevated for the first 4 h . Plasma cortisol returned to control levels by 24 h whereas β-endorphin was still elevated (P < 0.05) 24 h after castration. Plasma cortisol levels were elevated for the first 60 min following weaning (P < 0.005) and again at 24 h after dam removal (P < 0.001). Plasma β-endorphin was not elevated (P > 0.05) any time during the 72 h following weaning. Plasma cortisol (P < 0.001) and β-endorphin (P < 0.05) were elevated during the first 60 min following the start of 1 h of isolation. Results were similar for partial and total isolation. No effects of isolation were found for the next 23 h. Plasma cortisol (P < 0.005) was elevated during the first 30 min following 4 min of shearing-like restraint, whereas plasma β-endorphin was elevated only at 7 min (P < 0.05) after restraint began. No further effects of restraint were found prior to termination of sample collection at 24 h. None of the stressors employed affected plasma concentrations of T3 and T4. This study has shown that measurements of plasma cortisol and β-endorphin in blood samples obtained before, during and after stress are useful in assessing stress in lambs. The painful stressor, castration, induced marked and prolonged elevations of both hormones, whereas psychological stressors elicited graded, short-term cortisol responses and limited β-endorphin responses.Key words: Cortisol, β-endorphin, physical stress, psychological stress, lambs Mears, G. J. et Brown, F. A. 1997. Réponse du cortisol et de la ␤-endorphine aux stressants physiques et psychologiques chez les agneaux. Can. J. Anim. Sci. 77: 689-694. Nous avons suivi les niveaux plasmatiques de cortisol, de β-endorphine, de T3 et de T4 chez les agneaux avant, pendant et après une exposition aux stress afin d'évaluer les possibilités d'utilisation de ces hormones comme mesure objective des réponses au stress. Des agneaux étaient exposés à la caudectomie, à la castration, au sevrage, à l'isolement et à la contention. Douze agneaux femelles et 24 agneaux mâles étaient utilisés, dont 12 agneaux mâles étaient castrés par voie chirurgicale à l'âge de 3 semaines. La caudectomie réalisée dans les 24 heures suivant la naissance ne causait pas de relèvement (P > 0,05) des niveaux plasmatiques de cortisol ou de β-endorphine. En r...

Effects of previous experience on total blood and free iodothyronine responses to isolation, restraint and shearing in sheep (Ovis aries)

“…The significant changes described for total iodothyronines after isolation, restraint and shearing were not in accordance with past studies that showed that T 4 and T 3 concentrations were not (Mears and Brown 1997). These findings confirm that the effect of a handling experience may depend on the age at which the handling occurs, and it may be possible to exploit the sensitivity of sheep to learning at certain ages; habituating sheep to handling routines, familiarising them with yard configurations and training leader sheep at critical learning periods may improve later handling (Hargreaves and Hutson 1997).…”

“…In contrast, little is known regarding the involvement of thyroid hormones in response to stress (Fazio and Ferlazzo 2003;Ferlazzo et al 2007) and whether or not any total or free iodothyronines can be used as objective indicators of stress in domestic animals Fazio et al 2012;Fazio et al 2014b). Plasma T 3 and T 4 concentrations were not affected by tail docking, castration, weaning, isolation and restraint in lambs (Mears and Brown 1997). The goal of this study was to investigate whether there is an effect on thyroid hormone concentrations in peripheral blood in sheep exposed to the physical and mental stress of isolation, restraint and shearing, by taking into account the influence of previous exposure to shearing.…”

Psychobiological consequences of two different weaning methods in sheep

“…These results are in agreement with data recorded from sheep by Napolitano et al [ 17], showing that separation at 15 or 28 days of age did not induce an increase in cortisol level unlike separation at 2 days of age. On the other hand, they are in opposition with those of Mears and Brown [ 16] [17]. Although the titre of antibodies was reported to be lower when the antigens were injected 3 days after the stress, compared to an injection on the same day [7] [20] and Shaw et al [21] have shown.…”

Pathophysiologic mechanisms of pain in animals A review

“…Catecholamines are produced in response to stressful events (including pain), and this result in an increase in glycogenolysis and mobilisation of glycogen, predominantly from muscle tissue, and as a consequence an increase in lactate and glucose production. In addition to cortisol parameters, Shutt et al (1988) and Mears and Brown (1997) used changes in plasma immunoreactive beta-endorphin as an indicator of pain by means of RIA. Attempts have also been made to connect pain (caused by castration of male pigs) with fluctuations in the levels of tumour necrosis factor alpha, interleukin-1beta, C-reactive protein, serum amyloid A and haptoglobin in blood; however, no changes in the levels of these substances were revealed (Moya et al, 2008).…”