CONICET | Buscador de Institutos y Recursos Humanos

The continued or repetitive exposure to stressorsalong time leads to a physiological state defined as chronic stress. Thisphenomena affects different biological processes including the immune response,clearly impacting on the animals´ welfare. Avian are endothermic animals andrequire comfortable temperatures for optimal development (22ºC- 24ºC).Consequently, heat stress is one of the main concerns in warm weathercountries. The objective of this study was to analyze the effect of chronicheat stress and its recovery on cellular immune response in juvenile Japanesequail (Coturnix coturnix) females. Onehundred and eighty quail were housed in 6 rearing pen boxes. Birds in 3 of the boxeswere exposed to a temperature increase (from 24°C to 34ºC) during the lightingperiod throughout 9 days (Stress treatment). Birds in the other 3 boxesremained at 24°C during the whole study (Control treatment). Once stressprotocol ended, subsequent 15 days were considered as the recovery period. Differentsets of 6 birds per treatment were sampled at day 0 (basal), 3, 6, and 9 (heatstress), and at days 12, 15, 18, 21 and 24 (recovery). Percentage ofinflammation and Heterophil/Lymphocyte (H/L) ratio were determined as cellularimmune response variables. A two-way ANOVA showed an alteration in both casesin just 3 days of heat exposure and maximum effects on day 9. The percentage ofinflammation recovered basal levels 6 days after heat exposure and H/L ratiorequired an extra 3 days. Results suggest differential modulation of immune variableswith negative consequences after exposure to high temperatures. Findings are consistentwith increased stress induced circulating mediators. Heat stress would representan immune threat when sustained for 3 or more days therefore affecting animalwelfare and fitness. However, cellular immune responses also appear resilient needing6 to 9 days to recover basal levels.