Effects of calcium lactate on in vitro fertilization and embryonic development in cattle.

OBJECTIVE: Growing demand for embryo transfer is steadily expanding and further studies on in vitro fertilization of cattle. To assess the effect of calcium lactate by replacing Tyrode's albumin lactate pyruvate (TALP) medium composition during fertilization and embryonic development.

METHODS: Sodium lactate and CaCl2 were replaced with 2.0, 3.0, 4.5 mM calcium lactate for TALP medium during fertilization in Experiment 1. In Experiment 2, the concentrations of sodium lactate and CaCl2 were re-modified as control, in comparison with the same concentration of calcium lactate at 4.5 mM. Zygotes were moved to sequential media to match early-and late-stage environments. Embryonic development was examined on day 8 after insemination.

RESULTS: A 4.5 mM calcium lactate enhanced the rate of fertilization and blastocyst formation (p<0.0001, p<0.01, respectively). It represented differences in the reactive oxygen species (ROS) (p<0.01) and glutathione (GSH) levels (p<0.05) and increased blastocyst diameter and total cell number (p<0.05). In Experiment 2, fertilization (p<0.05) and blastocyst formation rates (p<0.01) were increased in 4.5mM calcium lactate under same concentration effect of sodium lactate and CaCl2. Additionally, it reduced the ROS (p<0.01) and increased the GSH levels (p<0.05), leading increase embryo quality.

CONCLUSION: The replacement of calcium lactate in TALP medium enhances fertilization and embryonic development while also improving oxidative stress. Specifically, it has been determined that a concentration of 4.5 mM calcium lactate is the most effective, irrespective of the varying concentrations of sodium lactate and CaCl2. This study presents a novel formulation of a modified TALP medium intended for implantation withing the bovine embryo industry. The current implications of the study are discussed in relation to previously stated objectives and hypotheses.