Arginase activity of ovarian structures in cows of Brown Swiss and its cross-breeds/Aktivnost arginaze u ovarijskim strukturama krava svicarske smede pasmine i njezinih krizanaca

Arginase is the last enzyme of the urea cycle. It catalyses the hydrolysis of L-arginine to L-ornitine and urea. The aim of this study was to investigate the presence of arginase activity in ovarian structures such as: Graaf follicles, GF (Medium and Large size, M- and L-size), Corpus Haemorrhagicum (CH), and various types of Corpus Luteum (CL) such as: cyclic CL (CCL), 2-4 month pregnancy CL (2-4 MCL) and 4-7 month pregnancy CL (4-7 MCL). Ovarian tissues of 62 cows (7-10 years old and Brown Swiss or its cross-breeds), collected from a local slaughterhouse, were used as material. The materials were divided into 6 experimental groups, as follows: MGF group (n = 7), LGF group (n = 21), CH group (n = 7), CCL group (n = 6), 2-4 MCL group (n = 9) and 4-7 MCL group (n = 12). Arginase activities were measured as 0.056 ± 0.017, 0.100 ± 0.016, 2.517 ± 0.521, 0.827 [+ or -] 0.190, 0.674 ± 0.106 and 0.833 ± 0.093 U/mg protein in all groups, respectively. Arginase activity in the CH group was significantly higher than that in the CCL, 2-4 MCL and 4-7 MCL groups (P