Effects of heat chronic stress on cellular immunity in Japanese quail (Coturnix coturnix).

KEMBRO, J. M.; VIDELA, E. A.; MARIN R.H.; NAZAR, F. N.

Simposio; X European Symposium on Poultry Welfare; 2017

Thecontinued or repetitive exposure to stressors along time leads to aphysiological state defined as chronic stress. This phenomena affects differentbiological processes including the immune response, clearly impacting on the animals´welfare. Avian are endothermic animals and require comfortable temperatures foroptimal development (22ºC- 24ºC). Consequently, heat stress is one of the mainconcerns in warm weather countries. The objective of this study was to analyzethe effect of chronic heat stress and its recovery on cellular immune responsein juvenile Japanese quail (Coturnixcoturnix) females. One hundred and eighty quail were housed in 6 rearing penboxes. Birds in 3 of the boxes were exposed to a temperature increase (from 24°Cto 34ºC) during the lighting period throughout 9 days (Stress treatment). Birdsin the other 3 boxes remained at 24°C during the whole study (Control treatment).Once stress protocol ended, subsequent 15 days were considered as the recoveryperiod. Different sets of 6 birds per treatment were sampled at day 0 (basal),3, 6, and 9 (heat stress), and at days 12, 15, 18, 21 and 24 (recovery).Percentage of inflammation and Heterophil/Lymphocyte (H/L) ratio were determinedas cellular immune response variables. A two-way ANOVA showed an alteration inboth cases in just 3 days of heat exposure and maximum effects on day 9. The percentageof inflammation 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.