Effects of Commercial and Homemade Extenders on Post-thaw Sperm Quality and Fertility of Semen from Ethiopian Indigenous Horro Chicken Breed

Abstract

Cryopreservation of spermatozoa represents an important strategy for in vitro programs designed for the conservation of the genetic material of livestock populations. The objective of this study was to evaluate the effects of homemade tris-egg yolk-based and commercial poultry semen extenders on post-thaw sperm quality, fertility, and hatchability of semen from the Ethiopian Indigenous Horro chicken breed. A total of 30 roosters were used for semen collection, and 160 adult hens were inseminated artificially. The collected, qualified, and pooled semen samples were divided into three groups. Each semen sample was diluted with a homemade tris-egg yolk-based extender, Dimethyl-formamide commercial extender, and Commercial Beltsville Poultry Extender. Each extended semen was further divided into 20 sterile tubes as replicates. The extended semen samples were cryopreserved in liquid nitrogen using standard procedures. Changes in post-thaw spermatozoa mass and progressive motility, in vitro viability, morphological abnormality, fertility, and hatchability were evaluated. The post-thaw evaluation showed a decrease in the mass and progressive motility, morphologically normal spermatozoa, and an increase in dead spermatozoa and spermatozoa with bent necks, compared to fresh semen. There were significant differences in progressive sperm motility, motility, and in vitro viability between commercial and homemade cryoprotectants. However, no significant difference was observed in mass motility across the extenders. The commercial Dimethyl-formamide extender was found to be the most suitable regarding the proportion of morphologically normal sperm and in vitro viability rate of cryopreserved sperm samples. There were no significant differences across all treatments in terms of fertility and hatchability rate. However, there was a significant difference between the control treatment and commercial extenders in terms of fertility and hatchability. The findings indicated favorable outcomes for a tris-egg yolk-based extender that was prepared locally with regard to the cryopreservation of poultry semen. Additional investigations are recommended to enhance the fertility and hatchability of the semen.