Carboxymethylchitosan with medium-molecular-weight affects kinectics and acrosome of stallion sperm after freezing/thawing.

This paper investigates the effects of adding a substance called carboxymethylchitosan to a semen freezing solution, hoping to improve the post-thaw condition of stallion sperm. However, the results showed that with higher concentrations of this substance, the sperm’s movement and integrity decreased.

Objective of the Study

• The researchers were trying to find ways to improve the conditions of post-thawed stallion semen by using a substance called medium-molecular-weight carboxymethylchitosan (CQm). This substance was mixed into a commercial semen freezing extender (Botucrio) at different concentrations.

Methodology

• Each week, ejaculates from four different stallions were obtained, with the total reaching 20.
• The semen was diluted in the Botucrio extender and supplemented with CQm at the following concentrations: control (0), 0.75, 1.5, and 3 mg/mL.
• The samples were then frozen and stored at -196°C. After being thawed, the samples were evaluated for various parameters like kinetics, membrane integrity, and mitochondrial membrane potential.

Findings and Conclusions

• The study results revealed negative impacts on sperm dynamics and acrosome integrity (a part of the sperm cell) when the concentration of CQm was raised. These results were observed for CQm concentrations of both 1.5 and 3 mg/mL.
• Various indicators such as total and progressive motility, curvilinear velocity, straight-line velocity, average path velocity, and wobble decreased significantly in comparison to the control group.
• Similarly, there was a decrease in the percentage of sperm with intact acrosomes in the group treated with 3 mg/mL of CQm as compared to the control group.
• The researchers concluded that higher concentrations of medium-molecular-weight carboxymethylchitosan in a semen freezing diluent could harm the kinematics and acrosome of stallion sperm after being frozen and thawed.