Browsing by Author "Dokuzeylul, B."

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Investigation of Effects of Low Ruminal pH Values on Serum Concentrations of Macrominerals, Trace Elements, and Vitamins and Oxidative Status of Dairy Cows
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Katsoulos, P.D.; Bilgiç, B.; Tarhan, D.; Ates, F.; Suat, S.; Kozat, S.; Dokuzeylul, B.
Due to the feeding system (high-concentrate diet) during the early lactation stage, ruminal pH in dairy cows follows a diurnal pattern and can remain below the critical level of 5.5 for extended periods of the day. This study aimed to evaluate the effect of low ruminal pH on blood concentrations of certain macrominerals, trace minerals, and fat-soluble vitamins and on the oxidative status of dairy cows during the first half of lactation. Fifty-three randomly selected lactating Holstein cows were used; blood and ruminal fluid samples were collected from all cows on days 30, 90 and 150 of lactation. Blood samples were obtained via coccygeal venipuncture, while the ruminal fluid was obtained by rumenocentesis and the pH was measured immediately after collection. Using a threshold pH of 5.5, samples were classified as normal (pH > 5.5) or low pH (pH ≤ 5.5). Serum concentrations of Ca, Mg, K, Cr, Mn, Zn, Se, and vitamins A, D3, E, and K were not significantly affected by ruminal pH, either by days in milk or by their interaction (p > 0.05). Plasma malondialdehyde and reduced glutathione followed the same trend (p > 0.05). Copper concentration was significantly higher (p < 0.05), and Fe concentration tended to be higher in cows with low pH compared to those with normal pH (p = 0.052). On day 150 of lactation, Cu, Fe, and Co concentrations were significantly higher in low-pH cows compared to normal-pH cows (p < 0.05). Low ruminal pH is associated with significant changes in serum concentrations of copper, iron, and cobalt but has no significant effect on the oxidative status of the animals or on the serum concentrations of the macro elements and fat-soluble vitamins studied. © 2025 Elsevier B.V., All rights reserved.
Redox Balance in Van Cats and It's Association With Age, Gender and Eye Color
(Hellenic veterinary Medical Soc, 2024) Bilgic, B.; Ozkan, C.; Moscati, L.; Kaya, A.; Dokuzeylul, B.; Kayar, A.; Or, M. E.
Objectives: The aim of this study was to determine the oxidative stress index and redox balance in healthy Van cats and to evaluate it's association with gender, age and eye color. Methods: 80 healthy Van cats from different eye color, gender and age were used in the study. All cats were grouped according to their age (A) as <12 months (A1, n=30), >= 1 and <3 years (A2, n= 22), >= 3 and <5 years (A3, n=12) ve >= 5 years (A4, n= 16); eye color (E) from left to right as blue-blue (E1, n=31), blue-amber (E2, n= 19), amber-blue (E3, n= 12), amber-amber (E4, n= 19) respectively and gender (G) as female (G1, n=43) and male (G2, n=37). Blood serum reactive oxygen species (ROM) and serum antioxidant power (PAO) analyzed and oxydative stress index (OSI) was measured in all groups. Results: There was no statistically significant difference between age, gender and eye color regarding ROM, PAO and OSI in healthy Van cats. Mean ROM (H2O2/dL), PAO (HClO/ml) and OSI CarrU/(mol HClO/ml)) were 1.79, 434.8 and 0.05, respectively ( P>0.05). Conclusions: Since oxidative stress plays a critical role as a biomarker of various diseases, determination of redox balance may provide a useful tool in healthy Van cats. It was observed that ROM, PAO and OSI were not affected by age, gender and eye color in healthy Van cats. Breed differences among cat population may lead to dramatic changes in redox balance.