Evaluation of sperm DNA damage in bulls by TUNEL assay as a parameter of semen quality.
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.
Animal Breeding and Reproduction Research Division, NARO Institute of Livestock and Grassland Science, Ibaraki 305-0901, Japan.
Kumiko
K
Takeda
Kyoko
K
Uchiyama
Masashi
M
Kinukawa
Takahiro
T
Tagami
Masahiro
M
Kaneda
Shinya
S
Watanabe
D000818:Animals; D002417:Cattle; D015925:Cryopreservation; D004249:DNA Damage; D005306:Fertilization; D020287:In Situ Nick-End Labeling / Q000379:methods*; D008297:Male; D012661:Semen; D055101:Semen Analysis; D012662:Semen Preservation / Q000379:methods; D013045:Species Specificity; D013081:Sperm Motility; D013094:Spermatozoa / Q000473:pathology*