Evaluation of sperm DNA damage in bulls by TUNEL assay as a parameter of semen quality

• Published in: Journal of Reproduction and Development 2015, Vol.61(3), pp.185-190
• Main Authors: TAKEDA, Kumiko, UCHIYAMA, Kyoko, KINUKAWA, Masashi, TAGAMI, Takahiro, KANEDA, Masahiro, WATANABE, Shinya
• Format: Article
• Language: English
• Subjects: Bull sperm; Conception rate; DNA damage; Original; Semen quality; TUNEL
• ISSN: 0916-8818; 1348-4400
• DOI: 10.1262/jrd.2014-140

Sperm DNA damage affects the conception rate resulting from human assisted reproduction technology. The objective of this study was to adapt the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay to provide a quality parameter for bull semen based on the detection of sperm DNA damage. Fresh semen was collected from two Japanese Black bulls (A, B) several times over the course of a year, and the percentage of TUNEL-positive spermatozoa (sperm TUNEL index) was determined. Individual differences in semen were detected using the sperm TUNEL index in these bulls (P < 0.01). The sperm TUNEL index of cryopreserved semen obtained from test-mated Japanese Black (n = 30, including two bulls with a conception rate lower than 10%) and Holstein (n = 34) bulls were analyzed. The average sperm TUNEL index and conception rate resulting from artificial insemination (AI) were 4.7% and 55.7% for Japanese Black, and 4.9% and 39.5% for Holstein, respectively. A weak negative correlation between sperm TUNEL index and conception rate was observed in Holstein bulls (P < 0.05). Semen samples from six bulls with more than 10% sperm TUNEL index were studied, and these samples showed low sperm viability. However, semen resulting in a very low conception rate did not have a high sperm TUNEL index. Although it would be difficult to predict a low conception rate resulting from AI using the sperm TUNEL index alone, the index can be used as an additional parameter to provide a more comprehensive description of semen quality.