Association of blood serum biochemical parameters with the follicular pattern of the ovaries and the OPU efficiency in donor heifers (Bos taurus L.) of the istoben breed

Increasing the number of cumulus-oocyte complexes (COCs) retrieved per one session of follicle puncture (OPU), as well as improving the quality of COCs in relation to their developmental competence, is a key factor in the effective use of donor cows in programs aimed at in vitro embryo production (IVP). The observed associations between the content of metabolites in the blood of females and in the follicular fluid of the ovary in which oocytes develop suggest that changes in metabolic status due to metabolic disorders can potentially create a suboptimal microenvironment for oocytes, thereby having a negative impact on the quality of oocytes and the success of OPU/IVP programs. In this work, for the first time, the associations of some biochemical parameters of blood serum with the quantity and quality of oocytes and their developmental competence in vitro was found. The aim of this work was to study the associations of the content metabolites and enzymes in blood with the follicular pattern of the ovaries and the efficiency of OPU/IVP in donor heifers. The studies were carried out on mature heifers (n = 6) of the Istoben breed from 22 to 24 months old with a hormonally synchronized estrus cycle. To obtain oocytes, a series of nine consecutive OPU sessions were performed on each donor twice a week (54 sessions in total). Blood sampling for biochemical studies was performed during hormonal treatment and at each OPU session. To characterize nitrogen metabolism, serum levels of total protein, albumins, globulins, urea nitrogen, creatinine, ALT and AST activity were determined. The parameters of carbohydrate-lipid metabolism were controlled by measurements of blood serum glucose, triglycerides, phospholipids, total bilirubin and cholesterol. To assess the status of mineral metabolism, the content of calcium, phosphorus, magnesium, iron, chlorides, and alkaline phosphatase activity in blood serum were determined. The concentrations of all detectable blood metabolites and enzymes were within the reference values, with the exception of alkaline phosphatase, which slightly exceeded the limits. The absence of indices of metabolic processes that "break out" from the norms, as well as insignificant and moderate coefficients of variation, allow exclude the influence of paratypical factors on the animal health status. The two-factor model, considering the Animal and the OPU session, explain 84.2-94.6 % of the variability in the content of the nitrogen metabolites, 86.9 % in glucose concentration, 51.0-94.5 % in lipid metabolites, 42.4-69.2 % in mineral metabolism indices and 99.9 % in alkaline phosphatase activity. The results of the correlation analysis showed the associations of the total number of follicles with the content of certain blood serum metabolites: albumin (r = -0.57, p function show_eabstract() { $('#eabstract1').hide(); $('#eabstract2').show(); $('#eabstract_expand').hide(); }