Activity of tissue enzymes in cows (Bos taurus) and yaks (Bos grunniens) kept under different environmental conditions

This paper is devoted to a comparative study of the transferase system, total bilirubin and its fractions in cows (Bos taurus) and yaks (Bos grunniens). The yak, as a half-wild animal inhabiting exclusively high-altitude areas and, at the same time, not requiring special care, has been attracting the attention of researchers for a long time. When analyzing the literature data, it becomes clear that many questions concerning these half-wild animals remain rather unexplored, which requires a detailed research. To determine the functional state of the liver, experimental yaks and cows were subjected to a biochemical analysis of blood serum. We studied simultaneously 40 clinically healthy yaks and cows of both sexes aged 2-3 years old. The experimental yaks were kept grazing in the Oroz farm, Ton district, Issyk-Kul region (>2200 m above sea level), and the cows had stall-walking keeping in peasant farms in Chui region (760 m above sea level). Examining the blood serum biochemical parameters, we evaluated the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the levels of total bilirubin, direct and indirect bilirubin using an automatic biochemical analyzer «PERFECT MINDRAY 400». The results of the experiments were statistically processed by biometric analysis methods considering the Student's t-test (td). The work was carried out in the biochemical laboratory of the Department of Biology, Faculty of Science, Kyrgyz-Turkey Manas University in Bishkek, Kyrgyzstan. Blood parameters are an indicator of the work of the whole organism, they can characterize the level of adaptation of animals to various environmental factors. Biochemical parameters in the blood serum of yaks and cows were mainly within the physiological norm. But in the serum of yaks kept in the highlands, the activity of AST increased from 90.47 ± 4.23 u/L to 124.2 ± 6.27 u/L (p<0.001), compared to the cows in the middle mountains. During the activity of the ALT enzyme, no significant changes were observed throughout the experiment (p>0.2). According to the results of statistical analysis in yaks, the coefficient of AST Cv variation - 19.5% showed an average variability. ALT also showed an average coefficient of Cv variation - 16.1%, whereas the coefficient of variation of ALT in cows showed Cv - 36.5%, which indicates a significant variability in the variational series. In its turn, AST showed an average coefficient of Cv variation - 18.1%. When carrying out statistical processing of the obtained data, we determined the statistical significance of the differences between yaks and cows from the given indices. With the number of degrees of freedom f=38, the minimum value that td takes is 1.70 (p>0.90) and 2.70 (p>0.999). The statistical significance of the differences between AST in yaks and cows showed a high degree, whereas ALT did not show any significant differences. Activation of tissue enzymes in the blood serum of yaks under high mountain conditions can alter the liver activity, that is why aminotransferase levels increased. During the study of the blood serum in yaks and cows, the level of total and direct bilirubin was within the physiological norm. In the blood serum of yaks, total bilirubin level was 0.63 ± 0.05 mg/dL, at the same time in the blood serum of cows from Chui oblast, total bilirubin level was 0.50 ± 0.06 mg/ dL ( p<0.05). When we examined bilirubin fractions, the following data were obtained: in yaks, direct bilirubin changed significantly, compared with cows, from 0.48 ± 0.07 mg/dL to 0.20 ± 0.05 mg/dL (p<0.001), and indirect bilirubin increased in the blood serum of cows from 0.15 ± 0.01 mg/dL to 0.30 ± 0.02 mg/dL (p<0.001). According to the results of statistical analysis in yaks, total bilirubin with a coefficient of Cv variation - 32.8% varied significantly, whereas direct bilirubin in yaks showed a high coefficient of Cv variation - 57.8%. Variability of the variational series of total and direct bilirubin in cows also showed a high coefficient of variation. The statistical significance of differences in total bilirubin in yaks and cows showed an unreliable quantity (p>0.90), and the significance of the differences in direct bilirubin was expressed in an average degree (p>0.95), whereas indirect bilirubin was highly reliable (p>0.999). Thus, different environmental conditions lead to changes in biochemical parameters in experimental animals. We showed that there were no significant changes in the activity of the ALT enzyme in the serum in experimental animals throughout the experiment. We established that the activity of the enzyme AST was higher in the serum of yaks than in cows. The levels of total and direct bilirubin in the blood serum of yaks were higher than those of cows. These data indicate a high level of metabolic processes in yaks, as well as adaptation to the natural environment.

Keywords

Authors

References