Effect of mid-embryonic thermal conditioning on zootechnical performance, immune-competence and expression profiling of HSP70 gene in backyard chicken variety

Embryonic thermal conditioning improves the thermoregulatory threshold response later in post-hatch period. Backyard poultry birds are more vulnerable to the pronounced effect of global warming due to their scavenging nature. This investigation was carried out to determine the effect of thermal manipulation (temperature 39.5˚C, d11-d16 of embryogenesis for 5h/day (ETM) vs standard incubational temperature 37.5˚(C) in CARI-Debendra backyard variety on zootechnical parameters, immune response and HSP 70 gene expression. Control embryos were incubated at temperature 37.5˚C and RH 60% in setter. There was no significant difference in hatchability of control (63.53%) and ETM (63.23%) group though the external pipping was 12h earlier in ETM group. The ETM chicks exhibited significantly (Pd”0.05) higher body temperature (97.81±0.28˚C vs 96.63±0.56˚C) than control chicks at hatching which waned into insignificance in adult life. First week and final body weight at 12 weeks of control and ETM group did not differ significantly. Significant difference was observed only in relative thigh weight, spleen weight at 6 weeks but not in cell-mediated immune response. Differential expression of HSP70 differs significantly in liver only between control and ETM group. This study improved the understanding of ETM with regards to thermotolerance in slow-growing dual-purpose CARI-Debendra variety preferred in tropical climate. In conclusion, mid embryonic thermal conditioning of 2.5˚C during E11-E16 improved the juvenile growth, immune-response and relative expression of HSP70 gene in slow growing chicken which signifies its adaptability and thermotolerance in hot and humid west coastal climate.