Effect of Dimethylacetamide Concentration on Motility, Quality, Antioxidant Biomarkers, Anti-Freeze Gene Expression, and Fertilizing Ability of Frozen/Thawed Rooster Sperm

Abstract

Sperm cryopreservation is of great importance for the poultry industry but still needs to be optimized. The high susceptibility of poultry sperm to cryodamage leads to low fertility rates after cryopreservation. Therefore, the present study aimed at evaluating the effect of including a cryoprotectant, dimethylacetamide (DMA), in the chicken semen freezing extenders at a final concentration of 3%, 6%, or 9% on the post-thawed sperm motility, quality, antioxidant biomarkers, anti-freeze gene expression, and fertilizing ability. Results showed that the total motile sperm, progressivity, and viability were quadratically increased (p < 0.05) in the 6% DMA group. The antioxidant enzyme activity and lipid peroxidation were negatively (p < 0.05) affected by the increase in DMA concentration. Furthermore, some anti-freeze-associated genes such as heat shock protein 70 (HSP70) and ras homolog family member A (RHOA) were linearly and quadratically down-regulated (p < 0.05) with the high concentration of DMA. Finally, the fertility and hatchability rates did not indicate statistical differences between DMA groups. It can be concluded that using the low concentration of 3−6% DMA in the freezing semen extender is preferable to obtain acceptable results in the post-thawed sperm quality and fertility.

Keywords: anti-freeze genes; antioxidant biomarkers; chicken; dimethylacetamide; fertility; motility; semen freezing.

Figure 1

Effect of dimethyl acetamide (DMA) concentration in freezing extender on the anti-freeze-associated gene expression of rooster sperm after thawing. Bars express the means of three samples (n = 3) as log₂ (fold change) ± standard error (SE). ^a–b Means with different superscripts, within the same gene, are significantly different (p < 0.05). HSP70: heat shock protein family A, RHOA: ras homolog family member A, SNPA1: small nuclear ribonucleoprotein polypeptide A′, RPL29: ribosomal protein L29. p-values of linear and quadratic effects are 0.021 and 0.038 for HSP70, 0.016 and 0.036 for RHOA, 0.032 and 0.005 for SNPA1, and 0.573 and 0.314 for RPL29, respectively.