International Journal of Poultry Science1682-83561994-7992Asian Network for Scientific Information10.3923/ijps.2019.293.300KammonAbdulwahab AlzentaniSamia TarhuniOmar AshegAbdulatif 62019186Objective: The aim of the experiment was to evaluate the effect of heat stress on body weight, immune response and cecal bacterial count in parent broiler chickens and to determine the ameliorating effects of some organic acids to overcome heat stress. Materials and Methods: Day-old, 1920 male broiler parent chicks were used in a 2×2 factorial completely randomized design. The experimental chicks were randomly and equally distributed into 2 major groups (960 chicks each) which further divided into 4 subgroups (480 chicks each) with 8 replicates. Two subgroups were exposed to heat (H) at 35°C from 22-42 days of age and the other two subgroups was lift normal. Four replicates in each subgroup were given organic acids (OA) in drinking water at the first week, days 19-27 and last week of age whereas the other 4 replicates in the same subgroup were given normal drinking water. Results: Heat stress caused significant decrease in body weight, coliforms count and serum lysozyme level at 5^{th} week of age. The body weight has been significantly ameliorated by organic acids. Deleterious effects of heat stress on immunity has been confirmed by the significant decrease of bursa/body weight ratio and total leukocyte count (TLC) at 4^{th} week of age. The bacterial count was significantly increased in the group exposed to heat at 5th week of age. Conclusion: It is concluded that heat stress has deleterious effects on chickens and organic acids has significantly ameliorated some of these effects.]]>Lara, L.J. and M.H. Rostagno,2013Janardhana, V., M.M. Broadway, M.P. Bruce, J.W. Lowenthal, M.S. Geier, R.J. Hughes and A.G.D. Bean,2009Richards, J.D., J. Gong and C.F.M. de Lange,2005Waldroup, P.W., E.O. Oviedo-Rondon and C.A. Fritts,2003Ricke, S.C.,2003Kirchgessner, M. and F.X. Roth,1988Runho, R.C., N.K. Sakomura, S. Kuana, D. Banzatto, O.M. Junqueira and J.H. Stringhini,1997Jin, L.Z., Y.W. Ho, N. Abdullah and S. Jalaludin,1998Lactobacillus cultures.]]>Gunal, M., G. Yayli, O. Kaya, N. Karahan and O. Sulak,2006Islam, M.Z., Z.H. Khandaker, S.D. Chowdhury and K.M.S. Islam,2008Ao, T., A.H. Cantor, A.J. Pescatore, M.J. Ford, J.L. Pierce and K.A. Dawson,2009Natt, M.P. and C.A. Herrick,1952Campbell, T.W., C.K. Ellis and B. Doneley,2007OIE.,2012Heckert, R.A., I. Estevez, E. Russek-Cohen and R. Pettit-Riley,2002Salanitro, J.P., I.G. Blake and P.A. Muirhead,1977Iannotti, E.L., J.R. Fischer and D.M. Sievers,1982Dawsom, K.A., B.E. Langlois, T.S. Stahly and G.L. Cromwell,1984Lie, O., M. Syed and H. Solbu,1986Mujahid, A.,2011Denli, M., F. Okan and K. Celik,2003Luckstadt, C. and S. Mellor,2011Owens, B., L. Tucker, M.A. Collins and K.J. McCracken,2008Pirgozliev, V., T.C. Murphy, B. Owens, J. George and M.E.E. Mccann,2008Bartlett, J.R. and M.O. Smith,2003Niu, Z.Y., F.Z. Liu, Q.L. Yan and W.C. Li,2009Ghazi, S., M. Habibian, M.M. Moeini and A.R. Abdolmohammadi,2012Bozkurt, M., K. Kucukyilmaz, A.U. Catli, M. Cinar, E. Bintas and F. Coven,2012Haque, M.N., K.M.S. Islam, M.A. Akbar, R. Chowdhury, M. Khatun, M.R. Karim and B.W. Kemppainen,2010Ghazalah, A.A., A.M. Atta, Kout . Elkloub, M. El Moustafa and R.F.H. Shata,2011Houshmand, M., K. Azhar, I. Zulkifli, M.H. Bejo and A. Kamyab,2012Aengwanich, W.,2008Prieto, M.T. and J.L. Campo,2010Felver-Gant, J.N., L.A. Mack, R.L. Dennis, S.D. Eicher and H.W. Cheng,2012Imtiaz, N., A. Sultan, S. Khan, A. Khan and H. Khan,2014Lokhande, P.T., G.B. Kulkarni, K. Ravikanth, S. Maini and D.S. Rekhe,2009Al-Saad, S., M. Abbod and A.A. Yones,2014Park, S.O., J. Hwangbo, C.M. Ryu, B.S. Park and H.S. Chae et al.,2013IgG and cecum microflora of broiler chickens.]]>Abdel-Mohsein, H.S., M.A. Mahmoud and U.T. Mahmoud,2014Adil, S., M.T. Banday, G.A. Bhat, S.D. Qureshi and S.A. Wani,2011Ali, M.N., A.A. Mahrous and F.G. Ahmed,2008