Diurnal changes in the hematological indices in the blood of racing Arabian horses.

In 8 stallions and 6 mares of pure Arabian horses the diurnal changes in the number and certain parameters of red and white blood cells were studied. All of them showed distinct diurnal changes but they did not fulfill the conditions of circadian rhythm according to Halberg. It was found that most of peaks occurred during the dark phase of 24 hr period except the percentage of eosinophils, erythrocyte diameters and cell rate sedimentation. The majority of indices studied showed the higher mean diurnal levels in the mares than in the stallions.