title: Effects of Enterobacter cloacae on boar sperm quality during liquid storage at 17°C.
abstract: Contamination of fresh and extended boar sperm often occurs in farms and artificial insemination (AI) centres during semen collection, processing and storage. The presence of bacteria produces detrimental effects on boar sperm quality, which may cause economic losses in reproductive centres. The present study has evaluated for the first time how the presence of Enterobacter cloacae affects the preservation of boar spermatozoa in liquid storage at 15-17 °C for an 11-day period. With this purpose, extended semen samples from seven healthy post-pubertal boars were artificially contaminated with different sperm:bacterium ratios (2:1; 1:1; 1:5 and 1:10) of E. cloacae. The 1:0 ratio (non-inoculated) served as a negative control. The most infective ratios (i.e. 1:5 and 1:10) significantly damaged sperm motility and membrane integrity, increased sperm agglutination, and decreased the osmotic resistance of spermatozoa. In contrast, the negative impact that the lowest bacterial concentration (2:1) had on boar sperm quality was clearly lower. In addition, other parameters such as pH were also more affected at the highest infective ratios (i.e. 1:5 and 1:10), despite no damage being observed on sperm morphology. In conclusion, the present work shows that damage inflicted by the presence of E. cloacae in boar sperm during liquid storage at 15-17 °C compromises the longevity and fertilising ability of seminal doses when bacterial concentration is higher than a 1:1 ratio. Further research is warranted to address by which mechanism E. cloacae impairs boar sperm quality.
authors.affiliation: Biotechnology of Animal and Human Reproduction (TechnoSperm), Department of Biology, Institute of Food and Agricultural Technology, University of Girona, E-17071 Girona, Spain.
authors.forename: Noelia
authors.initials: N
authors.lastname: Prieto-Martínez
authors.affiliation: Biotechnology of Animal and Human Reproduction (TechnoSperm), Department of Biology, Institute of Food and Agricultural Technology, University of Girona, E-17071 Girona, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Bussalleu
authors.affiliation: Biotechnology of Animal and Human Reproduction (TechnoSperm), Department of Biology, Institute of Food and Agricultural Technology, University of Girona, E-17071 Girona, Spain.
authors.forename: Estela
authors.initials: E
authors.lastname: Garcia-Bonavila
authors.affiliation: Biotechnology of Animal and Human Reproduction (TechnoSperm), Department of Biology, Institute of Food and Agricultural Technology, University of Girona, E-17071 Girona, Spain.
authors.forename: Sergi
authors.initials: S
authors.lastname: Bonet
authors.affiliation: Unit of Animal Reproduction, Department of Animal Medicine and surgery, Faculty of Veterinary Medicine, Autonomous University of Barcelona, E-08193 Bellaterra (Barcelona), Spain. Electronic address: marc.yeste@uab.cat.
authors.forename: Marc
authors.initials: M
authors.lastname: Yeste
mesh_terms: D000818:Animals; D016972:Enterobacter cloacae / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008297:Male; D012661:Semen / Q000382:microbiology*; D055101:Semen Analysis / Q000662:veterinary*; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013094:Spermatozoa / Q000382:microbiology / Q000502:physiology; D013552:Swine / Q000502:physiology*; D013696:Temperature
keywords: Boar semen; Enterobacter cloacae; Liquid storage at 17°C; Sperm quality