Taurine Reduces Heat Stress by Regulating the Expression of Heat Shock Proteins in Broilers Exposed to Chronic Heat

The aim of the current study was to investigate the effects of taurine on heat stress by evaluating them RNA and protein expressions of HSP90, 70 and 60in Ross broilers. Birds were distributed in a control group (CO) reared at 24 degrees C, a heat-stress group (HS) maintained at 34 degrees C (weeks 3-5) and not supplemented with taurine, and a heat-stress group (HST) maintained at 34 degrees C (weeks 3-5) and supplemented with 0.1% taurine from 2 weeks of age. The final body weight was significantly higher in the HST group than in the HS group (p<0.05). The mRNA expression of all three genes in the liver and of HSP90 in the muscle were significantly lower in the HST than in the HS group (p<0.05). In the liver, the expression of HSP70 and HSP60 proteins was significantly higher in the HS group compared with the CO and HST groups (p<0.05), while HSP90 expression was not different (p>0.05). In the muscle, HSP70 expression was significantly lower in the HST group than in the CO and HS groups and HSP60 expression was dramatically decreased in HS group, whereas no differences in HSP90 expression were detected among groups. In conclusion, the broilers exposed to heat stress and supplemented with taurine showed lower expressions of heat shock genes and proteins both in the liver and muscle tissues, indicating that taurine supplementation improved broiler thermo-tolerance.