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چکیده
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Heat stress results in detrimental consequences on nutrients digestion and absorption; however the underlying molecular mechanism is not clearly understood. To investigate the effects of high ambient temperature on gene expression of nutrient transporters in the jejunum of broiler chickens, Seventy-two male broiler chickens with similar body weights were randomly allocated into two groups (control, 24 ± 1°C and heat stressed, 32 ± 1°C) at 35 d of age. The chickens in heat-stressed group underwent ten hours heat exposure daily from 0800 to 1800 and then were raised at 24± 1°C. Rectal temperature and feed intake were recorded daily. After seven days, eight chickens per group were sacrificed by exsanguinations and the jejunum was collected. The results showed that heat exposure significantly decreased feed intake and increased rectal temperature. The plasma concentrations of uric acid and triglyceride were significantly increased and decreased respectively in heat-exposed broiler chickens. No significant changes were observed in the plasma level of glucose, total amino acids and VLDL of heat-exposed chickens, however, plasma glucose tended to be higher (P=0.09) in the heat-exposed chickens. Heat exposure had no significant effect on the mRNA levels of Na+-dependent glucose transporter 1 and amino acid transporters (y+LAT1, CAT1, r-BAT and PePT-1). However, the gene expressions of GLUT2, FABP1 and CD36 were significantly decreased by heat exposure. The current findings suggested that periodic heat exposure might alter the jejunal glucose and lipid transports rather than amino acids transporters, which provided new insights to the mechanisms underlying heat stress effects on nutrient absorption in broiler chickens.
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