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The present study was carried out during October 2007 to July 2008 in five different combinations of maximum temperature (Tmax) / minimum temperature (Tmin) viz. P1: <20oC/<10oC; P2: >20oC/<10oC, P3: >30oC/<15oC; P4: >35oC/<20oC and P5: >35oC/>20oC. The study aimed to investigate the expression pattern of superoxide dismutase enzymes viz. Mn-SOD mRNA and Cu,Zn-SOD mRNA in relation to physiological responses of Sahiwal and Karan-Fries cattle. Physiological indices revealed no significant breed differences indicating similar levels of heat adaptability. During P1, expression of Mn-SOD was higher in KF than in Sahiwal while during P5, expression of Cu,Zn-SOD was higher in KF than in Sahiwal (p<0.05). Mn-SOD expression in Sahiwal increased with cold stress while Cu,Zn-SOD expression in KF increased with hot stress (p<0.05).