Results 62 Productive and Physiological Responses of Two Broiler Genotypes to Thermal Conditioning, Protein Regimen and Their Tolerance To Heat Stress Waleed Shaaban Ahmed Abd Alla Habashy MSc. Poultry production Damanhour University 2011 E-Mail : walid.habashi@agr.dmu.edu.eg www.Damanhour.edu.eg Web Site : RESULTS 4.1 Growth Rate: Data presented in Table (3) showed the effect of broiler strain, thermal condition and dietary protein regimen on growth rate of broiler chickens. Results indicated that thermal conditioning had a significant negative effect on growth of broilers during days 3-4, 22-42 and 1-42 of age. Genotype and CPR had a significant effect on growth during days 3-4 and 1- 21 of age. Table (3): Main effect of thermal condition, dietary protein regimen and broiler strain on growth rate of broiler chickens. Body weight gain Treatment Days1-42 Days 22-42 Days 1-21 Days3-4 Thermal condition b 6725 b 6611 566 7.88 b TC a 6771 a 6671 561 13.2 a C 1016 1016 NS 101116 P value 5015 7021 1066 1011 SEM Protein regimen 6751 6656 527 a 11.0 a HHCPR 6772 6656 HSCPR 6721 6617 517 b 10.1 b SHCPR 6516 6677 SSCPR NS NS 1011 10112 P value 66015 61056 1066 10165 SEM Strain 6772 6621 b 517 a 6606 Hub 6751 6651 a 517 b 7051 A.A NS NS 101116 10112 P value 5015 7021 1066 1011 SEM a,b , Means within a column not sharing a common superscript are significantly different P> 0.05; NS= not significant, TC=thermal conditioning, C= Control