title: Relationship between sperm apoptosis and bull fertility: in vivo and in vitro studies.
abstract: The objectives of this study were to confirm the relationship of apoptosis-associated membrane and nuclear changes in bull spermatozoa with field fertility, to predict the fertility of beef bulls used for natural breeding and to study the role of DNA-nicked spermatozoa in early embryonic development. In Experiment 1, the relationship between fertility and different sperm populations identified by the Annexin V/propidium iodide (PI) and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assays was determined. Bull fertility was related to live (P < 0.05) and necrotic (P < 0.01) and DNA-nicked (P < 0.001) spermatozoa. In Experiment 2, the percentage of DNA-nicked spermatozoa was determined in 15 beef bulls used for natural breeding and their fertility potential was determined using a regression model developed in Experiment 1.The predicted fertility deviation of beef bulls ranged from -7.3 to 2.4. In Experiment 3, the effect of DNA-nicked spermatozoa on in vitro cleavage and blastocyst rates was evaluated, using 30 000 or 300 000 spermatozoa per droplet. Cleavage rate was adversely affected (P < 0.05) by DNA-nicked spermatozoa, regardless of sperm concentration. Blastocyst rate was lower (P < 0.05) in high DNA-nicked spermatozoa at the lower sperm concentration. In conclusion, the incidence of DNA-nicked spermatozoa is a useful marker to predict a bull's fertility potential. DNA-nicked spermatozoa showed adverse effects on early embryonic development.
authors.affiliation: Cryobiology Lab, Canadian Animal Genetic Resource Program, Agriculture and Agri-Food Canada, Saskatoon Research Center, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.|Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.
authors.forename: Lauren
authors.initials: L
authors.lastname: Erickson
authors.affiliation: Semex Alliance, 130 Stone Road West, Guelph, ON N1G 3Z2, Canada.
authors.forename: Tom
authors.initials: T
authors.lastname: Kroetsch
authors.affiliation: Cryobiology Lab, Canadian Animal Genetic Resource Program, Agriculture and Agri-Food Canada, Saskatoon Research Center, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.|Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.|Corresponding authors. Emails.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Anzar
keywords: DNA nicks; beef; blastocyst; cleavage; dairy; membrane asymmetry