A Review on the Conservation of South African Indigenous Poultry Breeds: A Focus on Semen Cryopreservation.

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.