# Optimizing thyroxine levels for enhanced buffalo sperm cryopreservation and fertility: a focus on quality, viability, and antioxidant protection

## TL;DR

Adding thyroxine to buffalo semen improves sperm quality, viability, and fertility after freezing, with optimal results at 0.75 µg/dL.

## Contribution

The study identifies thyroxine as a novel cryoprotectant for buffalo semen, optimizing its concentration for improved sperm preservation and fertility.

## Key findings

- Lower thyroxine concentrations (0.1–0.9 µg/dL) improved sperm motility and viability compared to higher concentrations.
- The 0.75 µg/dL thyroxine group showed the best sperm velocity, membrane integrity, and antioxidant protection.
- Thyroxine-treated semen had higher cryosurvival and conception rates, indicating improved fertility outcomes.

## Abstract

This study investigated the effects of adding thyroxine (T4) to buffalo semen on sperm quality, oxidative markers, apoptosis-like changes, and fertility.

Initially, we tested a wide range of T4 concentrations (0.1, 0.3, 0.9, 2.7, and 8.1 µg/dL) to evaluate their impact on motility and viability.

Lower concentrations (0.1–0.9 µg/dL) improved total and progressive motility and viability compared to higher concentrations (2.7 and 8.1 µg/dL). We assessed optimized doses (0.25, 0.5, 0.75, and 1 µg/dL) based on these findings. The 0.75 µg/dL group showed superior sperm velocity, viability, motion parameters, membrane, acrosome, and DNA integrity in equilibrated and frozen-thawed samples. Antioxidant markers (GPx, SOD, TAC) were enhanced, while MDA and apoptotic/necrotic cell levels were reduced, particularly in the 0.75 µg/dL group. Fertility trials revealed higher cryosurvival and conception rates in thyroxine-treated groups. In conclusion, T4 supplementation, especially at 0.75 µg/dL, enhances cryopreservation outcomes and fertility potential of buffalo bull semen.