Componentes de origem animal e vegetal na conservação do sêmen de pequenos ruminantes

Abstract

Artificial insemination is recognized for its practicality, both economically and in terms of efficiency, in ensuring the genetics of high-yield animals, with semen preservation being an essential part of this process to guarantee fertility. Thus, the objective of this review was to present research and studies that prove the importance of animal and plant-based diluents in the preservation of refrigerated or cryopreserved semen from small ruminants. The processes for semen preservation are refrigeration and cryopreservation; however, the use of these methods results in significant damage to spermatozoa, affecting metabolism, especially mitochondrial function, decreasing enzymatic activity related to oxidative phosphorylation, decreasing ATP production, and reflecting in a decrease in sperm motility. In goats, cooling the semen causes marked damage due to the active presence of phospholipases and lipases in the seminal plasma, a characteristic specific to the species. In sheep, although the activity of these enzymes is lower, prolonged cooling also impairs sperm quality, increasing the number of cells with compromised membranes. Diluents should contain an efficient buffer system, such as sodium phosphate, sodium citrate, TRIS (tris-hydroxymethylaminomethane), or TES (N-tris(hydroxymethyl) methyl-2-aminoethanesulfonic acid). In addition, energy sources such as glucose and fructose, as well as cryoprotectants, must be present. Diluents must contain an efficient buffer system, such as sodium phosphate, sodium citrate, TRIS (tris-hydroxymethylaminomethane), or TES (N-tris(hydroxymethyl) methyl-2-aminoethanesulfonic acid). In addition, energy sources such as glucose and fructose must be present, as well as external cryoprotectants such as egg yolk or animal milk, and internal cryoprotectants such as glycerol (GLY) and ethylene glycol (EG). In contrast to animal-derived diluents, plant-derived diluents are used for their antioxidant action, which protects against oxidative stress, as well as plant compounds that act physically and chemically on the lipids present in the membrane. Therefore, semen diluents have proven to be essential in semen preservation. Animal-derived diluents are the most widely used due to their known efficiency, and various plant-derived diluents are emerging as promising alternatives to replace animal-derived ones.