The Effects of Environmental Temparature and Vitamin C on Thyroid Hormones of Blood Serum and Some Haematological Values in Swiss Brown Bulls


Abstract: The present study was carried out to investigate the effect of different environmental temperatures and vitamin C administration on the levels of serum thyroid hormones, some haematological values, respiration rate (RR), pulse rate (PR) and rectal temperature (RT) in Swiss Brown bulls. For this purpose, a total of 84 healthy animals were used in the experiment. At two month intervals during one year, the amount of 50 ml/week vitamin C solution containing 20% ascorbic acid (n:7) and the same amount of sterile physiological saline (n:7) were intramuscularly injected into the bulls, which were at the same conditions of maintenance and nutrition, within 4 weeks. During the same period, samples of blood were taken RR, PR and RT levels of the animals were measured and the data of environmental temperatures were recorded. The levels of serum total thyroxine, total triiodothyronine, free thyroxine, free triiodothyronine and thyroid stimulating hormone, erythrocyte counts, haemoglobin (Hb) amounts and haematocrit values in the bulls were found to be at lower levels in high environmental temperatures (20.8°C; 39.3% relative humidity (RH) and/or 23.7°C; 20.0% RH) than in low environmental temperatures (3.2°C; 63.3% RH and/or 5.3°C; 77.0% RH), although erythrocyte sedimentation rate after 1 and 2 hours, leukocyte counts, the amounts of RR, PR and RT in the animals in the low environmental temperatures were lower than those in the high environmental temperatures. Decreased Hb amount caused by the high ambient temperature (20.8°C; 39.3% RH) was increased by vitamin C administration. However, vitamin C did not have any significant influence on the other parameters that were examined in this study. Based on the results, it was determined that the different environmental temperatures caused some parameters investigated in Swiss Brown cattle to change and vitamin C was not an effective agent in restoring those parameters, except Hb.

Keywords: Environmental temperature, vitamin C, thyroid hormones, haematological parameters, cattle.

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