Humanin levels predict semen quality and cryotolerance in crossbred cattle bulls
Background
The reproductive performance of crossbred cattle bulls is often hampered by unpredictable semen quality, freezability, and fertility, significantly impacting breeding programs and genetic improvement efforts. Current methods for assessing semen quality can be insufficient for reliably predicting post-thaw viability and fertility. Identifying novel, reliable biomarkers is crucial for selecting superior ejaculates. Humanin, a mitochondria-derived peptide, has emerged as a potential candidate due to its roles in cellular protection and mitochondrial function, making its presence in sperm and seminal plasma of interest for reproductive health.
Study Design
Researchers assessed Humanin presence in sperm and seminal plasma from 49 ejaculates collected from three Vrindavani crossbred bulls. Semen quality was evaluated for volume, individual progressive motility (IPM), abnormality, and sperm concentration. Ejaculates were categorized into normozoospermia, oligozoospermia, asthenozoospermia, and oligoasthenozoospermia. Normozoospermic ejaculates were cryopreserved and retrospectively grouped into good-freezable and poor-freezable based on post-thaw motility (PTM). Immunofluorescence assays were used to localize Humanin within sperm.
Results
Humanin was successfully identified in the neck and upper midpiece regions of sperm via immunofluorescence. Seminal plasma Humanin levels were significantly higher (p < 0.05) in normozoospermic individuals compared to other semen quality groups. Furthermore, Humanin levels in seminal plasma showed a positive and significant correlation with both sperm concentration and individual progressive motility (IPM) (p < 0.05). Out of 28 normozoospermic ejaculates, 19 ejaculates (67.86%) were classified as good-freezable, while 9 ejaculates (32.14%) were poor-freezable. Importantly, the Humanin level in the seminal plasma of good-freezable ejaculates was significantly (p < 0.05) higher than that observed in poor-freezable ejaculates. This indicates a strong association between Humanin levels and the ability of sperm to withstand cryopreservation.
Humanin levels in seminal plasma were significantly higher (p < 0.05) in normozoospermic individuals and in good-freezable ejaculates, establishing its potential as a robust indicator of semen quality and cryotolerance.
Key Findings
- Humanin peptide is present in the neck and upper midpiece regions of bull sperm.
- Seminal plasma Humanin levels are significantly higher in normozoospermic ejaculates (p < 0.05).
- Humanin levels positively correlate with sperm concentration and individual progressive motility (p < 0.05).
- Good-freezable ejaculates exhibit significantly higher seminal plasma Humanin levels (p < 0.05).
Why It Matters
Humanin can serve as a practical biomarker for selecting high-quality, freezeable semen in crossbred cattle breeding programs. This finding offers a significant advancement for livestock reproduction, potentially improving the efficiency of artificial insemination by allowing for the early identification and utilization of superior ejaculates. By incorporating Humanin assessment into routine semen evaluation, breeders could reduce the economic losses associated with poor-quality or non-freezable semen, thereby enhancing genetic progress and overall herd fertility. This moves towards a more predictable and effective breeding strategy, directly impacting the success rates of animal husbandry.
humanin
semen quality
cryotolerance
cattle
vrindavani
biomarker