Impact of chilling duration on sperm quality of indigenous buck semen in the Coastal Area of Bangladesh

Abstract

Background: Assessing semen characteristics is an important step before semen preservation. This study aimed to collect, evaluate, and preserve indigenous buck semen in the coastal area of Bangladesh. Methods: The study was conducted at the Theriogenology and Animal Reproductive Biotechnology Laboratory, Department of Medicine, Surgery and Obstetrics, Patuakhali Science and Technology University, from July 2021 to June 2022. We selected four bucks based on non-return rate, pregnancy rate of does, and various parameters including age, body weight, scrotal circumference, and testicular epididymal length. These selected animals received a regimen of vitamins, minerals, anthelmintics, and concentrated feed. Semen was collected using the artificial vagina method, and data on color, odor, volume, viscosity, mass activity, consistency, concentration, and individual sperm motility were recorded and analyzed after collection. Results: The semen of bucks exhibited a creamy white color and a fishy odor. The mean (±SD) of scrotal circumference (SC) of four bucks was 20.43±0.52, while the testicular epididymal length (TEL) was 11.03±0.59. Buck-2 (B-2) and buck-1 (B-1) showed significantly (p<0.05) higher volumes than buck-3 (B-3), and buck (B-4). B-1 also displayed significantly (p<0.05) higher mass activity compared to B-2, B-3, and B-4. In addition, B-2 and B-1 showed significantly (p<0.05) greater consistency than B-3, and B-4. The highest concentrations were observed in B-2 and B-1 compared to B-3 and B-4. In terms of individual sperm motility, B-1 showed significantly (p<0.05) higher motility (81.0±05.16) than B-2 (71.0±03.94), B-3 (66.0±03.94), and B-4 (80.0±07.45). Regarding chilling duration, a significant reduction in sperm motility was observed during storage at 4°C. This indicated that sperm motility varied significantly (p ≤ 0.000) with varying chilling durations. Conclusions: The study suggests that the individual progressive sperm motility at 4°C gradually decreases but remains suitable for artificial insemination up to 72 h (≥50±7.65). B-1 and B-2 demonstrated relatively promising results in semen evaluation and preservation. Further study is necessary to determine the pregnancy rate of does after insemination with chilled semen.