Understanding the Crucial Role of Seminal Plasma Exosomes in Bull Fertility: A Review

Bull fertility is a multi-factorial trait and is affected by many factors, such as nutrition, genetics, and epigenetics. Superior quality male germplasm with high genetic merit helps to improve the livestock production trait. To achieve the target of livestock production, the availability of superior male germplasm is a great concern. In developing countries, there is a gap between the highly fertile frozen semen doses produced and the highly fertile frozen semen doses required. Improving the quality of existing low-fertile semen from high genetic merit bulls seems to play a promising role in filling this gap. Seminal exosomes are extracellular vesicles secreted by the epithelial cells of the testis, epididymis, and accessory sex glands such as the prostate gland. They contain a cargo of bioactive molecules such as proteins, nucleic acids and various metabolites. These molecules are transferred to the spermatozoa during its maturation and help in sperm capacitation, maturation, acrosome reaction, and fertilisation. Studies reveal that seminal exosomes help to improve the sperm functionality of low-quality sperm. Identification of the molecular profile of exosomes of bulls with proven fertility and their addition in an extender containing low-fertile semen may help to ameliorate the sperm quality of low-fertile semen, which may eventually aid in generating quantities of highly fertile ejaculates.