DOI: n/a
Abstract
The aim of the present investigation was to carry out a comparative study on the changes in the values of thyroid hormones, total protein and blood glucose in free-reared cows, depending on the physical activity during their dry period, their physiological status and the breed. The experiment was carried out with three groups of cows of two breeds – Bulgarian Black and White and Brown Cattle. The control group of animals was free-reared and fed indoors, with an access to a small yard for a stroll. The animals of the first experimental group were reared under the same conditions with an additional 2 km daily stroll and those of the second group – under the same conditions with an additional 4 km daily stroll. All the groups were reared in the same premises. Blood was taken from 5 cows from the two breeds in dynamics, as follows: when drying off the cows, 7-5 days before calving and 5-7 days after calving. The blood samples were taken from the same animals in the different periods. The results of the investigation showed that during pregnancy the concentration of thyroid hormones was higher (although within physiological levels) compared to the period after calving for the animals of the control group and for the animals of the other groups with different physical activity, independent of the breed. Blood glucose values were slightly influenced by the physical activity and lactation and the excessive physical activity had a negative effect on the synthesis of total proteins, including globulins.