Abstract: The present study was conducted to determine the adverse effects of cyclic high temperature on mitochondrial function and breast meat quality of broilers. One hundred eighty 4-week-old broilers were allocated to three treatments according to following design: 25 ℃, ad lib. feeding (Control); 25 ℃, pairfeeding with the high cyclic group (PF); and 28 ℃/34 ℃ daily cyclic high temperature, ad lib. feeding (Cyclic). Broilers were kept in three environment control chambers for three weeks. Heat exposure significantly elevated hepatic mitochondrial H2O2 production and muscular and hepatic lipid peroxidation, significantly inhibited muscular and hepatic mitochondrial Ca2＋-ATPase activity. Increased plasma CK and LDH were found under cyclic high ambient temperature, which indicated that the muscle intracellular free Ca2+ was increased and muscle cell membrane integrity was damaged. At 49 day, Consistent with cyclic high temperature induced alterations in mitochondrial function were changes in breast muscle glycolytic metabolism as indicated by lower muscle pH immediately postslaughter (pHi), and higher drip loss, L*and shear force. At 25 ℃, restrict feeding had no significant effects on mitochondrial function, muscle pH, L*, and drip loss, which indicated that effects of cyclic high temperature on mitochondrial function and breast meat quality of broilers were not associated with declined in feed intake.

Key words: cyclic high temperature, mitochondrial, ROS, Ca2＋-ATPase, breast meat quality, broilers