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Characterization, quantification and removal of potential pathogens from stallion semen

Al-Kass, Ziyad (2019). Characterization, quantification and removal of potential pathogens from stallion semen. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2019:17
ISBN 978-91-7760-352-8
eISBN 978-91-7760-353-5
[Doctoral thesis]

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In Sweden, equine artificial insemination is most frequently carried out with liquid semen rather than frozen semen. Many factors affect sperm quality during semen storage, including the presence of bacteria and addition of antibiotics. Use of Single Layer Centrifugation (SLC) or Modified SLC (MSLC) has been shown to improve sperm quality, resulting in an increase in the time for which the sperm sample retains its function during storage. These techniques can also separate spermatozoa from bacteria. The purpose of this thesis was to investigate the role of MSLC, antibiotics and bacteria on sperm quality and storage time. This thesis comprised 4 studies: Study I was a retrospective study of potential pathogenic bacteria isolated from Swedish stallion semen during the period 2007 to 2017. Study II was to identify bacteria in semen by conventional laboratory culture methods. Study III was to isolate pathogenic and nonpathogenic bacteria in stallion semen using metagenomic analysis. Study IV was to investigate the effect of MSLC and the effect of presence or absence of antibiotics in the extender on sperm quality. Our results showed that potentially pathogenic bacteria such as Taylorella equigenitalis, Klebsiella pneumoniae, beta haemolytic streptococci and Pseudomonas aeruginosa appeared infrequently in Sweden. However, many nonpathogenic bacteria were found. Metagenomic analysis enabled more bacteria to be identified than other methods. The bacterial genera identified were different between studies, animals and ejaculates, even from animals kept on the same stud. Corynebacterium spp. were the most frequently found non-pathogenic bacteria identified in all our studies. The bacterial population was decreased using MSLC, sperm quality was improved and the shelf-life of the sperm samples was increased. The presence of antibiotics in the extender did not affect sperm viability. The bacterial population was greater in samples without antibiotics than in samples with antibiotics; bacteria appeared in all samples, even those with extender containing antibiotics. There was no evidence that bacteria isolated from a stallion on one stud should also be isolated from other individuals on the same premises. More work is needed to investigate the effects of particular bacterial genera on sperm quality. In addition, it would be interesting to investigate the shape and size of bacteria in relation to spermatozoa and the proportions of different bacteria removed using MSLC. Further modifications to the SLC technique might enable the removal of more bacteria.

Authors/Creators:Al-Kass, Ziyad
Title:Characterization, quantification and removal of potential pathogens from stallion semen
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2019
Number of Pages:75
IAl-Kass, Z., Eriksson, E., Bagge, E., Margareta, W. & Morrell, JM.*. Bacteria detected in semen and pre-ejaculatory fluid of Swedish stallions from 2007 to 2017. (Submitted).
IIAl-Kass, Z., Eriksson, E., Bagge, E., Margareta, W. & Morrell, JM.* Conventional diagnostics to identify bacteria in semen from stallions in Sweden. (Manuscript).
IIIAl-Kass, Z., Guo, YZ., Pettersson, OV., Niazi, A. & Morrell, JM.*. Metagenomic analysis of bacteria in semen from Swedish stallions. (Manuscript).
IVAl-Kass, Z., Spergser, J., Aurich, C., Kuhl, J., Schmidt, K., Johannisson, A. & Morrell, JM.* (2018). Sperm Quality during Storage Is Not Affected by the Presence of Antibiotics in EquiPlus Semen Extender but Is Improved by Single Layer Centrifugation. Antibiotics, 7, 1-13.
VAl-Kass, Z., Spergser, J., Aurich, C., Kuhl, J., Schmidt, K. & Morrell, JM* (2019). Effect of presence or absence of antibiotics and use of modified single layer centrifugation on bacteria present in pony stallion semen. Reproduction in Domestic Animals, 54, pp. 342–349. https://doi.org/10.1111/rda.13366.
Place of Publication:Uppsala
Publisher:Department of Clinical Sciences, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-352-8
ISBN for electronic version:978-91-7760-353-5
Publication Type:Doctoral thesis
Article category:Other scientific
Full Text Status:Public
Agris subject categories.:L Animal production > L53 Animal physiology - Reproduction
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 403 Veterinary Science > Clinical Science
Keywords:Modified Single Layer Centrifugation, male fertility, microorganism, liquid semen, sperm quality, 16S sequencing, pony stallions, semen evaluation
Permanent URL:
ID Code:16021
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Clinical Sciences
Deposited By: SLUpub Connector
Deposited On:21 Mar 2019 13:56
Metadata Last Modified:31 Mar 2019 13:46

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