Impact of acute metabolic acidosis on the acid-base balance in follicular fluid and blood in dairy cattle.

Acid-base balance is one of the most vigorously regulated variables of the body, including genital organs. Subacute ruminal acidosis is a common disturbance in dairy cows that disturbs several biochemical indices in the blood, cerebrospinal fluid, and urine. The possible negative effects of metabolic acidosis on the follicular fluid (FF) composition and, subsequently, on oocyte quality, are not fully elucidated. This study aimed to evaluate the changes in acid-base balance (ABB) in FF and blood during acute metabolic acidosis in dairy heifers. Ten Holstein heifers were stimulated with FSH in eight decreasing doses at 12-hour intervals (D0-D3). Acidosis was induced by oral administration of sucrose at 9 g/kg of body weight, dissolved in 10 L of warm tap water, at D3. Samples were collected from each cow at 0, 8, 12, 16, 24, 32, 40, and 48 hours after treatment. Samples of FF, obtained by transvaginal follicular aspiration, and peripheral blood were examined for ABB parameters: pH, pCO2 , pO2 , HCO3 - , and base excess (BE). A significant decrease in pH, HCO3 - , and BE values in the blood, as well as FF, occurred after sucrose treatment. The lowest pH values occurred in blood at 16 hours, and in FF at 24 hours, after treatment (7.30 ± 0.05 and 7.33 ± 0.05, respectively). The lowest HCO3 - values in blood (18.75 ± 3.2 mmol/L) and FF (18.07 ± 2.84 mmol/L) occurred 24 hours after treatment, as did the lowest BE values (-6.61 ± 3.7 mmol/L and -7.53 ± 3.89 mmol/L, in blood and FF, respectively). Significant correlations for HCO3 - (r = 0.928), BE (r = 0.946), pH (r = 0.889), and pCO2 (r = 0.522) existed between blood and FF samples. The results demonstrated that metabolic acute acidosis substantially influences the characteristics of both serum and FF.