Sexual maturity and physical exercise alter fibrinolytic activity in birds (chickens)

1. Sexual maturity in the domestic hen is accompanied by hyperlipidaemia. This study examined effects of hyperlipidaemia on fibrinolytic activity at rest and following prolonged treadmill exercise. 2. In immature hens the mean pooled-plasma fibrinolytic activity was 50 mm2 and following 90 min continuous exercise this rose to 114 mm2. In contrast, fibrinolytic activity in mature hens was undetectable but rose to 51 mm2 after exercise. 3. The fibrinolytic response of mature and immature cocks was comparable to that of the immature hens. 4. The resting plasma triglyceride concentration in mature hens was approximately seven times that of the immature hens, immature and mature cocks. Exercise induced significant increases in plasma non-esterified fatty acid concentrations but had no significant effect on triglyceride or cholesterol levels. 5. The results demonstrate that prolonged exercise in birds, as in man, evokes hyperfibrinolysis. However, the response is impaired in mature females and this may be associated with increased blood lipid levels.