The plants’ extracts have recently emerged as a cheap and natural source of additives to preserve and enhance sperm functions during the cryopreservation process. Extracts from plants are reported to be the main sources of natural antioxidants with lower cytotoxicity as compared to therapeutic antioxidants. The numerous and valuable plant properties, such as antioxidants, antimicrobial, antiviral, anti-inflammatory, and antiparasitic, have been linked to plant extracts. Numerous plant extracts from different species have been used as preservatives for livestock semen cryopreservation. During these processes, the extracts are added to the semen extender in different doses to keep the sperm motile and viable throughout the cryopreservation, including during pre-freezing, equilibration, and post-thawing. The sperm quality parameters can be improved by adding these natural compounds that exert protection against bacteria and reactive oxygen species scavengers in semen extender. Although the application of plant extracts as preservatives for semen storage is still emerging, their potential is promising. They represent natural and economically viable alternatives to the conventional additives currently employed for semen preservation. This review focuses on the aspects related to plant extracts and their role during cryopreservation of semen from domesticated livestock species.

Understanding the genetic, physiological, and nutritional characteristics of native chickens in South Africa has been significantly hindered by studies over the last ten years. These chickens hold significant economic, social, and cultural importance for South African communities, particularly those marginalized. Despite their reputation for lower egg productivity, they are highly valued for their flavorful meat by consumers. Many local chicken ecotypes and breeds remain undocumented and in danger of going extinct, even though some have been classified. To tackle this issue, the Food and Agriculture Organization has launched an indigenous poultry conservation program. One crucial method employed is assisted reproductive biotechnologies such as cryopreservation, which serves as an ex situ conservation strategy for preserving the germplasm of endangered animals. In avian species, cryopreservation is particularly beneficial for the long-term storage of sperm cells, although it necessitates the use of cryoprotectants to shield sperm cells from cold shock during freezing. However, the use of cryoprotectants can lead to thermal shocks that may damage the sperm cell plasma membrane, potentially reducing viability and fertility. Furthermore, the membranes of avian sperm cells are highly polyunsaturated fatty acids, which can undergo lipid peroxidation (LPO) when reactive oxygen species (ROS) are present. This review focuses on current knowledge and the latest effective strategies for utilizing cryopreservation to conserve semen from indigenous poultry breeds.

Epididymal sperm preservation provides an alternative means of utilizing valuable bull genetic material when conventional semen collection is not possible. However, sperm quality declines during liquid storage, partly due to oxidative stress and the absence of protective seminal plasma components. This study evaluated the cytotoxicity of hexane Pelargonium graveolens extract in Vero cells and its effects on the quality of liquid-preserved bull epididymal sperm. Cytotoxicity of the extract was first assessed in Vero cells using the MTT assay. Subsequently, twenty bull testes were collected from a local abattoir, and epididymal spermatozoa were recovered by retrograde flushing. Samples were diluted in a Tris-based extender containing 0, 2.5, 5, 7.5 or 10 mg/mL hexane Pelargonium graveolens extract and stored at 5°C for 120 hours. Sperm motility and kinematic parameters were evaluated at 0, 24, 48, 72, 96 and 120 hours using the Sperm Class Analyzer® system. Data were analysed using the General Linear Model procedure. The extract reduced MTT-derived Vero-cell viability, with the lowest mean viability (5.28%) at 2.5 mg/mL; the response across intermediate concentrations was not consistently monotonic. At 120 hours, the 5 mg/mL treatment recorded the highest total sperm motility (87.52 ± 4.49%) and differed from the control (59.42 ± 4.49%), whereas the 2.5, 7.5 and 10 mg/mL treatments did not differ from the control. Non-progressive motility did not differ among treatments. These results suggest that, at optimal concentrations 5 mg/mL hexane Pelargonium graveolens extract can serve as a natural epididymal sperm additive, while higher concentrations (10 mg/mL) appeared less effective in preserving sperm quality, highlighting the importance of dose optimization. Future studies should investigate extracts prepared using solvents of different polarity to determine whether additional bioactive compounds further improve sperm preservation. Moreover, identifying and optimizing specific compounds could help determine those that are both safe and effective for bull epididymal sperm preservation.