[The effect of low temperatures on biochemical indicators in the blood of calves]

Twenty calves, heifers of the Holstein-Friesian breed and crossbreds with the Slovak Pied breed, were divided into two groups at the average age of 19 days. The trial group was kept outdoors in wooden hutches and the control group was housed in an insulated building. Blood was sampled at the age of 20, 33, 48 and 60 days at the outdoor temperatures of 3 degrees C, -2 degrees C, -5 degrees C and -8 degrees C. The calves kept in hutches where temperatures were always lower than in the insulated calf-house had the higher level of nonesterified fatty acids in all observations. The largest, highly significant difference was determined at the age of 60 days at the outdoor temperature of -8 degrees C (271 mumol/l vs. 224 mumol/l), and the significance of differences was also observed in the first and third blood samplings at the temperatures of 3 degrees C and -5 degrees C. The differences were highly significant in the first group between the first and fourth, and second and fourth samplings. In the calves kept in the insulated building the difference was significant between the first and fourth observation because the content of free fatty acids was also gradually increasing in this case (Tab. I). Glycaemia values were also higher in the calves kept in hutches (Tab. II). The most noticeable (significant) difference was determined at the age of 48 days at the outdoor temperature of -5 degrees C (4.3 mmol/l vs. 3.9 mmol/l). Significant differences within the group were recorded only in calves from the trial group kept in hutches. Insulin concentrations increased gradually with the older age of animals (Tab. II). At the age of 20 days the values were identical in fact in both groups and the highest concentrations were recorded at the age of 60 days. The differences between the groups were not significant, the largest difference was observed at the end of milk feeding period at the age of 60 days (19 microUI/l in calves from hutches and 15.6 microUI/l in calves from the insulated building). Triiodothyronine concentrations decreased from the starting values of 0.8 nmol/l and 0.76 nmol/l in both groups at the age of 33 days to the values of 0.61 and 0.62 nmol/l.(ABSTRACT TRUNCATED AT 400 WORDS)