Electrolytes, Metabolic And Acid-Base Parameters In Blood And Fluids of The Reproductive Tract During In Vivo Maturation of Bovine Oocytes

Follicular fluid is the microenvironment that supports oocyte maturation and competence. Using Abbott iSTAT1™ and NanoDrop, we determined the dynamics of acid-base, electrolyte, metabolites, and total protein in venous blood, fluids of the dominant follicle (FF), oviduct (OF), and uterus (UF) during the window of oocyte maturation. Holstein heifers (n=36) were synchronized with PGF 2α on Days -11 and 0, CIDR during Days -6 to 1, and GnRH given on Day 2 after 2 nd PG. Samples were collected at 24h, 48h, 60h, 72h, and 78h after 2 nd PG. Most electrolytes analyzed, Cl - , K + , and Ca 2+ were significantly affected in blood and FF (P<0.05) by CIDR removal. Similarly, Cl - and Na + also significantly changed in OF and UF across time. Glucose, lactate, and creatinine significantly changed across time points in FF compared to blood. Moreover, pO 2 , pCO 2 , TCO 2 , and pH significantly changed across time in FF. Most parameters were not significantly correlated between blood and FF across time points except for glucose, Cl - and creatinine. Furthermore, pO 2 in FF was nearly 3X higher than blood, suggesting low O 2 during in vitro maturation is inappropriate. In conclusion, components of the follicular fluid undergo major changes during the window of oocyte maturation.