Freezability and fertility of Thai native chicken semen in different diluents
The objective of the present study was to compare the efficacy of three diluents on post-thaw motility, viability, and fertility of frozen chicken semen. Semen from Thai native cocks (Pradu Hang Dam; n=24) was collected, pooled, and randomly allocated into three groups, then diluted at a ratio of 1:3 (v:v) with Schramm, EK, and polyvinylpyrrolidone (PVP)-based medium. The diluted semen samples were cooled down to 5ºC and then mixed with Dimethylformamide (DMF) (6% v/v). Semen straws were subjected to cryopreservation using liquid nitrogen vapor method. For cryopreserved sperm quality assessment, the frozen semen straws were thawed, and motility was assessed by computer-assisted sperm analysis (CASA). Viability was evaluated using a SYBR-14/PI live/dead sperm viability kit. Lipid peroxidation level was measured based on malondialdehyde (MDA) levels. Fertility was also examined by inseminating layer hens (n=36) with the frozen semen. The experimental results showed that sperm motility and viability were superior when using Schramm and EK diluents, compared to PVP-based medium (P ≤ 0.05). The Schramm and EK diluents yielded lower levels of MDA and higher fertility than the PVP-based medium (P ≤ 0.05). The present study indicated that Schramm and EK diluents were the suitable cryopreservation media for native chicken; the diluents could maintain the quality of native chicken semen after freezing-thawing.