Effects of Extenders Supplementation with Gum Arabic and Antioxidants on Ram Spermatozoa Quality after Cryopreservation

Abstract

Semen cryopreservation is very important in animal agriculture to maximize the number of daughters of genetically superior males and to distribute the cryopreserved semen of good males all over the world. However, the freezing process generates some damage to sperm that reduce their fertilizing ability after thawing. Moreover, egg yolk, which is the most common animal-origin cryoprotectant used in semen dilution, is considered a source of biosecurity risk. In the current study, we aimed to compare the replacement of egg yolk in the extender by gum arabic (5%) along with supplementation with antioxidant cysteine or ascorbic acid on semen quality and freezability in Noemi rams in vitro. Semen from six rams were collected with an artificial vagina two times per week. Semen evaluation parameters such as color, volume, pH, general motility, percentage motility, concentration and cell viability ratio were assessed. Spermatozoa motility and concentration were estimated with the computer-assisted semen analysis system. The semen samples were frozen using a Tris extender containing either 15% egg yolk or 5% gum arabic. For antioxidant-supplemented extenders, cysteine or ascorbic acid was dissolved at concentrations of 0.10, 0.50 or 1.0 mM in egg yolk or gum arabic extender. The semen from each ejaculate of each ram were resuspended with a specific extender with glycerol (5%); the final volume after dilution was 1 mL semen to 4 mL extender. The samples were then cooled to 4 °C for 120 min, loaded into 0.5 mL straws and frozen in liquid nitrogen for 7 days. Supplementation of gum arabic or egg yolk extenders for ram semen with antioxidants such as cysteine or ascorbic acid has beneficial effects on semen quality after cold storage or cryopreservation. However, supplementation of a 5% gum arabic extender with cysteine at 0.5 or 1 mM concentration or ascorbic acid at 0.5 mM concentration improved the quality of spermatozoa postcryopreservation. It could be concluded that gum arabic is a good alternative for egg yolk in Noemi ram semen extenders. Antioxidants are necessary to support the addition of gum arabic to the extender to help the ram spermatozoa to survive freezing–thawing and oxidative stresses.

Evaluation of Kappa‐carrageenan supplementation in extender for post‐thaw Kajli ram sperm quality

“…However, our findings are against those of Shehab‐El‐Deen et al. (2023), who did not observe any significant difference in acrosome integrity at any of the concentrations of gum arabic, a polysaccharide. Although the mechanism is unclear, the difference in acrosome integrity can be attributed to the structural differences and their interaction with cellular components.…”

“…Nevertheless, only some pertinent research papers are reported concerning the application of k-carrageenan oligosaccharides in the cryopreservation of gametes. Supplementation of k-carrageenan oligosaccharide in the semen extender of rooster and canine sperm showed improved post-thaw quality (Chung et al, 2003;Shehab-El-Deen et al, 2023). This improvement in post-thaw quality is attributed to hydrogen bonding groups present in it and its ability to lower the phase transition temperature, which prevents crystal formation, thereby ensuring enhanced sperm integrity (Gastal et al, 2017).…”