Investigation of silk protein sericin use for the short-term storage of rabbit sperm at 4 and 15°c

Objective: To investigate the effect of sericin and temperature (4 and 15°C) on short term storage quality of rabbit semen Material and Methods: The study was performed in three experiments. In the first and second experiment, semen pool (from five ejaculates) was diluted to 50M ml−1 sperm concentration, and divided into control, 0.1% and 0.5% sericin groups, later further divided to 4 or 15°C partitions. Sperm motility was analyzed by CASA and livability, membrane and acrosome integrity were checked at 0, 24, 48, and 72 h of storage for all semen samples. In vivo fertility was assessed in third experiment. Results: 0.5% sericin groups showed higher rates of sperm motility and acrosome integrity compared with 0.1% sericin and control group at 4°C. At 15°C, 0.1% sericin showed significantly higher percentage of sperm motility, membrane integrity at 24, 48 and 72 h, respectively. Similarly, higher viability and acrosome integrity was found at 15°C (P < 0.05) for 0.1% sericin group at 72 h. As a whole, the parameters i.e. total motility, viability, membrane and acrosome integrity were significantly higher (P < 0.05) for 0.1 and 0.5% sericin treated samples stored at 15°C than at 4°C. Pregnancy rates for does inseminated with control were lower (50, 42.8%) than 0.1% sericin (66.6, and 71.4%) at 4 and 15°C (P > 0.05), respectively. However, litter size was similar in all groups and 0.5% sericin group had higher pregnancy rate (57.1%) for 15°C doses than 4°C (33.3%). Conclusion: It was concluded that 15°C was better than 4°C for the short-term storage of rabbit semen, and both 0.1 and 0.5% sericin supplementation improved quality of chilled rabbit semen.