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

VIDELA, EMILIANO ARIEL; NAZAR FRANCO NICOLÁS; KEMBRO JACKELYN MELISA; MARIN, RAUL H.

Simposio; X European Symposium on Poultry Welfare; 2017

World's Poultry Science Association, W.P.S.A.

The continued or repetitive exposure to stressors along time leads to a physiological state defined as chronic stress, affecting biological processes including the immune response, thus diminishing animal welfare. Avian are endothermic animals and require comfortable temperatures for optimal development (22ºC- 24ºC). Consequently, heat stress is one of the main concerns in warm weather countries. The objective of this study was to analyze the effect of chronic heat stress on cellular immune response in young Japanese quail (Coturnix coturnix) females, analyzing also time for response recovery. 180 quail were housed in 6 rearing boxes. In 3 boxes temperature was increased from 24ºC to 34ºC during light period throughout 9 days (Stress factor). Once stress protocol ended, subsequent 15 days were considered as recovery period. 9 independent sampling points were stablished every three days (Time Factor): basal (day 0), heat stress (days 3, 6 and 9) and recovery (days 12, 15, 18, 21 and 24). Percentage of inflammation and Heterophil/Lymphocyte ratio were measured as cellular immune response representative variables. Results were analyzed by means of a two-way ANOVA that evaluated the effects of Stress, Time and their interaction. Chronic heat stress affected parameters differentially, leading to a significant suppression of both on day 9. Percentage of inflammation had the fastest recovery (day 15), while Heterophil/Lymphocyte ratio required an extra three days to recover (day 18). Results inform about a differential modulation of the variables and negative consequences of the continued exposure to high temperatures, expectable when circulating mediators of stress response are increased. Heat stress would represent a threat if sustained for 3 or more days, reaching the highest damage reported at day 9, when animal welfare and fitness could be critically affected. Full cellular immune responses recovery would take a period of 9 days, with partial recovery at day 6