The effect of astaxanthin supplementation on the post-thaw quality of dog semen.

Astaxanthin is a member of the carotenoid family well known for its anti-cancer, anti-diabetic, anti-inflammatory, and antioxidant nature. This study was designed to investigate the effects of astaxanthin supplementation of the extender (buffer 2) on post-thaw dog semen quality. Semen from four healthy dogs was collected by digital manipulation twice a week. The ejaculates were pooled, washed, divided into four equal aliquots, diluted with the extender supplemented with different concentrations of astaxanthin (0, 0.5, 1, and 2 µM), and cryopreserved. The results showed that 1 µM astaxanthin was the optimum concentration that led to significantly higher (p < 0.05) post-thaw motility, kinematic parameters, and viability than the other groups. In comparison with the control group, sperm samples supplemented with 1 µM astaxanthin showed significantly higher (p < 0.05) sperm counts with intact membranes (55.7 ± 0.6% vs. 51.3 ± 0.9%), intact acrosome (58.4 ± 0.7% vs. 53.5 ±0.6%), active mitochondria (54.9 ± 0.5% vs. 42.6 ± 0.6%), and normal chromatin (67.6 ± 0.9% vs. 61.7 ± 0.6%). Furthermore, astaxanthin-supplemented samples showed significantly lower expression levels (p < 0.05) of pro-apoptotic (BAX), oxidative induced DNA damage repair (OGG1), oxidative stress-related (ROMO1) genes and higher expression levels of anti-apoptotic (BCL2), and sperm acrosome associated (SPACA3) genes compared to the control. Thus, supplementation of 1 µM astaxanthin in semen extender results in improved freeze-thaw sperm quality of the dog.