Bacterial growth in long-term preserved boar semen: effects of extender and storage temperature

• Published in: Animal reproduction science 2022-12, Vol.247, p.107113, Article 107113
• Main Authors: Luther, Anne-Marie, Nguyen, Thu Quynh, Beckermann, Christina, Verspohl, Jutta, Waberski, Dagmar
• Format: Article
• Language: English
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/j.anireprosci.2022.107113

The use of antibiotics in boar semen extenders is under debate. Loss of efficiency and ban of their use for animals reinforce search for alternatives. The effect of bacteria on sperm quality depends on the bacterial species and storage duration. Moreover, the type of semen extender and storage temperature could influence bacterial growth. The aim was to study the effects of semen extenders and storage temperature on growth of an array of commensal and multi drug resistant bacteria. In the first study, boar semen (n = 12) was extended in two extenders (BTS or AndroStar Premium [APrem]) and inoculated with a mixture of four commensal bacteria species, all isolated from field samples, to an initial load of 103 to 104 CFU/ml. After 144h storage at 17 °C in absence of antibiotics, bacterial counts after culture on blood agar had increased in BTS to 4 ×105 CFU/ml (p 0.05). In the second study, spiking of antibiotic-free BTS and APrem with 103 to 104 CFU/ml multi drug resistant Serratia species and Klebsiella species (n = 3 sample repetitions) resulted in rapid bacterial growth by 2 to 3log levels in both types of extenders during 144h storage at 17 °C. In samples stored at 5 °C in APrem (n = 3), as previously shown to maintain high sperm quality and fertility (Waberski et al., Sci. Rep. 2019, 9:14748), bacterial growth of Klebsiella species was reduced by one log level and of Serratia species by three log levels to