Effect of Heat Shock at Early Growth Phase on Glucose and Calcium Regulating Axis in Broiler Chickens

The present study was carried out to investigate the effect of different heat shock programs at early growth phase on glucose and calcium regulating axis in broiler chickens. The Comparison of body weight gain between different experimental groups showed that relative growth rate was significantly reduced in heat shock treated groups at fist week of age. After this period, the heat exposed groups gradually showed a compensatory growth and at the end of starter period the relative growth rate was significantly higher in heat shock treated groups compared to control group. The exposure of heat shock at the beginning of rearing period (day 3-6) and at the end of rearing period (day 42) has significantly increased plasma calcium levels. After the heat shock period, no differences in plasma calcium concentrations was found. The plasma glucose level was significantly reduced during temperature conditioning in heat shock treated groups compared with control group. After heat shock conditioning, plasma glucose levels returned to normal situation indicating that no differences in plasma glucose concentrations could be detected. There were no differences in plasma triglycerids concentrations between experimental groups. The results indicate that the glucose and calcium metabolism axes is one of the most important target in pre-heat shock conditioning to reduce mortality in broilers raising. Probably, the exposure of heat shock at early growth phase in broiler chickens can improve the bird`s thermotolerance ability to heat shock at higher ages by rapid response of birds to provide glucose via stored resources. In conclusion, exposure of heat shock at early growth phase in spite of improved bird`s final performance and survival ability during acute heat shock at later ages, can be used as a suitable model to understand the biological phenomenon related to the mechanisms of thermoregulation.