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Aim: The present experiment was conducted to study the effect of different tropical stress conditions on haemato-biological traits in various broiler strains during 3 to 4 weeks of age. Introgressing some important major genes likes Naked neck (Na) and Frizzle (F) into broiler germplasm may substantially improve the heat tolerance. Materials and Methods:The experiment was designed to evaluate three indigenously developed broilers viz. CARIBRO-Tropicana (Naked neck and Frizzle gene bearing), CARIBRO-Mritunjai (Naked neck gene bearing) and CARIBRO-Vishal (Normal plumaged) under different THI (i.e. 72, 85 and 91) for 4 hours daily for 7 days. Total 324 broiler chicks (i.e. 36 chicks in each group) of 3 weeks of age were used in this study. Results:The m-RNA expression of HSP-70 gene was observed highest in frizzle plumaged birds and lowest in normal plumaged birds. The CARIBRO-Vishal showed highest stress as compared to other group. Higher the THI more severe was the effect on the traits. During the 7 day of exposure trial birds of all the genetic group exhibited the phenomenon of acclimatization as reveled by the averages of various traits at different days into the exposure. The mRNA expression analysis of HSP-70 in liver revealed higher expression levels at later days during the exposure trials which indicated the phenomenon of memory (stress memory) and acquired thermotolerance. Conclusion:Among the three genetic groups, CARIBRO-Tropicana exhibited highest means for HSP-70 production as well as tolerated the heat stress in a better way; therefore CARIBRO-Tropicana was adjudged to be the best genetic group for production under tropical climate.

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The present experiment was conducted to study the effect of different tropical stress conditions on biochemical traits in various broiler strains during 3 to 4 weeks of age. Introgressing some important major genes likes Naked neck (Na) and Frizzle (F) into broiler germplasm may substantially improve the heat tolerance. Hence, the experiment was designed to evaluate three indigenously developed broilers viz. CARIBRO-Tropicana (Naked neck and Frizzle gene bearing), CARIBROMritunjai (Naked neck gene bearing) and CARIBRO-Vishal (Normal plumaged) under different THI (i.e. 72, 85 and 91) for 4 hours daily for 7 days. Total 324 broiler chicks (i.e. 36 chicks in each group) of 3 weeks of age were used in this study. The changes in blood biochemical parameters (i.e. Na, K, Glucose and ACTH) were examined in these experiments at 0 th , 3 rd and 7 th into exposure trials. The glucose, ACTH were observed lowest in frizzle and highest in normal plumaged birds under different THI. In experiment Na and K were observed higher in Frizzle and lowest in normal plumaged birds under different THI. The CARIBRO-Vishal showed highest stress as compared to other group. Higher the THI more severe was the effect on the traits. During the 7 day of exposure trial, birds of all the genetic group exhibited the phenomenon of acclimatization as reveled by the averages of various traits at different days into the exposure.