LIPID PEROXIDE LEVELS AND SUPEROXIDE-SCAVENGING ABILITIES OF SERA OBTAINED FROM HOTBRED (THOROUGHBRED) HORSES

Hotbred (Thoroughbred) horses were grouped into three classes accordin g to the levels of constant physical exercise (foals, 6 months old; ra cing horses, 5 years old; horses for breeding, 6-10 years old), and li pid peroxide levels in their sera were measured as thioburbituric acid -reactive substances. No significant differences were observed among t hem. The superoxide-scavenging abilities of sera were measured next; t o examine the antioxidative properties of hotbreds, and were found to be highest in the racing horses. The higher scavenging ability of the racing horses might contribute to keep their lipid peroxide levels as low as those of the other two groups. HPLC analysis of substances in s era suggested that the presence of albumin-bound bilirubin was one of the reasons for the high superoxide-scavenging ability of sera of the racing horses. When the hotbreds were compared with coldbred (crossbre d) horses, the lipid peroxide level of hotbreds was higher (7.0 +/- 1. 2 nmol/ml) than that of coldbreds (2.6 +/- 0.7 nmol/ml). Comparison of the superoxide-scavenging abilities of sera between hotbreds and cold breds showed that the hotbreds possessed higher scavenging ability tha n the coldbreds. These results indicated that the lipid peroxide level in sera of hotbreds was higher than that of coldbreds regardless of t he higher superoxide-scavenging abilities of sera.