Serum activities of lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT), and creatine phosphokinase (CPK), and serum levels of Na+ and K+ were measured in blood samples from healthy broilers and from broilers suffering from Sudden Death Syndrome (SDS) within 30 min after death. The LDH activity was higher in 4- to 9-wk-old SDS birds than in healthy birds (P < 0.05). The GOT activity was higher in SDS birds irrespective of age (P < 0.05). The CPK activity of SDS birds was not significantly different from that of healthy birds. The K+ level was about twofold higher in SDS birds of 4 to 6 and 7 to 9 wk of age than in healthy birds of the same age, whereas the Na+ level did not differ from that of healthy birds. The LDH, GOT, and CPK activities and Na+ level were unchanged for the post-mortem period of 30 min, but the K+ level increased. These results suggest that an elevations in serum LDH and GOT activities occur in association with SDS, and may be used as a characteristic sign of birds that are dying of SDS.
