Poloxamer 188 and hydroxyethyl starch have a cryoprotective synergic effect improving post-thawing quality and fertility of rooster spermatozoa

Poloxamer and hydroxyethyl starch have cytoprotective effects. In the present study, effectiveness was evaluated of these compounds as a cryoprotectant for rooster semen. In Experiment 1 (E1), poloxamer 188 (1%, P188), poloxamer 407 (1%, P407), and control groups were compared after sperm cryopreservation. Experiment 2 (E2) was conducted with 3%, 5%, and 7% of hydroxyethyl starch (H3, H5, H7), also combined with P188 (H3P188, H5P188, H7P188), based on results from E1. Sperm motility was assessed using CASA, abnormal forms and hypo-osmotic swelling (HOS) were evaluated using microscopy, and viability, apoptotic-like changes, and mitochondrial activity were determined using flow cytometry. In E2, there were assessments of fertility and hatching capacity. Results from E1 indicated total and progressive motility, velocity, membrane functionality, viability, and mitochondrial activity were greater with inclusion of P188 in semen extender, with less apoptotic-like changes (P < 0.05). In E2, HES inclusion in semen extender improved total motility, membrane functionality, and mitochondrial activity (P < 0.05), especially H5, which also markedly increased sperm viability and decreased apoptotic-like changes. The combination of P188 with HES increased sperm quality overall, with inclusion of H5P188 resulting in increases of progressive motility and VSL (P < 0.05). The H5 inclusion also increased proportion of fertilized eggs (P < 0.05). Furthermore, the combination of HES and P188 increased proportions of fertilized and hatched eggs compared with the control, with inclusion of H5P188 having the greatest effects. In conclusion, supplementation of semen extender with H5P188 increases post-thawing quality and fertility of rooster sperm, being a safe and effective method for the poultry industry.