The Effects of Extender Energetic Substrate Type on Goat Sperm Stored at 17 °C

TL;DR

This study found that pyruvate is better than glucose for preserving goat sperm quality during refrigeration, which could improve artificial insemination techniques.

Contribution

The study identifies pyruvate as a superior energetic substrate for preserving goat sperm during refrigeration compared to glucose.

Findings

Pyruvate and lactate extenders preserved higher sperm motility and viability over 48 hours at 17 °C.

Glucose negatively affected sperm viability and increased motility at higher concentrations.

NaCl supplementation and osmolarity had no significant impact on sperm quality parameters.

Abstract

Understanding how energy sources influence sperm performance could lead to optimized semen preservation techniques and ultimately benefit reproductive technologies and livestock breeding programs. Currently, extenders formulated for goat buck sperm primarily contain glucose as the main energy source. However, despite recent efforts to optimize extenders, no significant successful improvement in artificial insemination with cooled semen stored for over 24 h has been reported. The current study aimed to investigate the effect of pyruvate, lactate, glucose, and fructose on sperm during refrigeration at 17 °C. Pyruvate proved to maintain better sperm quality parameters than the other substrates after 48 h of storage at 17 °C in PBS.

Artificial insemination in goats commonly relies on refrigerated semen doses, yet the optimal energetic substrate to support sperm metabolism remains unclear. This study aimed to evaluate the effects of different energetic substrates on goat buck sperm metabolism and motility when refrigerated at 17 °C. Semen from six Murciano-Granadina male goats were collected and diluted in PBS supplemented with 35 mM of either glucose, fructose, pyruvate, or lactate in the first experiment. In the second experiment, the effects of varying concentrations of pyruvate and/or glucose, NaCl supplementation, and the osmolarity on sperm quality parameters were assessed. Semen was stored at 17 °C for 48 h and evaluated for motility using the CASA system, as well as for viability, mitochondrial membrane potential, and mitochondrial ROS by flow cytometry. The results show that pyruvate and lactate extenders outperformed the others, preserving higher total motility, progressivity, and viability of spermatozoa over 48 h, even at a concentration lower than 35 mM, as in the case of pyruvate. In contrast, glucose had a detrimental effect on sperm quality, reducing viability and healthy population rates while increasing motility, especially at higher concentrations. NaCl supplementation and osmolarity had no significant effect on any of the sperm quality parameters. In conclusion, pyruvate maintains a higher quality and motility of sperm stored at 17 °C in PBS in comparison with a glucose-supplemented extender.

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