3 thoughts on “Bacteria in processed semen; how bad? where do they come from?

  1. I’ve heard reports of a dairy herd in Northern Vic that used straws containing bacteria that rendered the cows infertile. It took a while to determine the cause of their infertility.

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    1. There are always a few bacteria in processed semen, although large numbers would usually indicate some failure of biosecurity, hygeine and/or the antibiotics used in the extender. Some bacteria can be seen under phase/DIC due to movement, while others might be seen adhering to sperm or as background aggregations.
      Depending on bacterial type and numbers, sperm can be adversely affected by direct destruction of membranes, by the instigation of apparent sperm abnormalities, by reducing motility and by changing pH.

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  2. Semen is not sterile. Some bacteria may be seen in raw [neat] semen, as well as extended semen. Antibiotics added to semen will not eliminate all bacteria, and are bacteriostatic, not bacteriocidal. The tylosin, gentamicin, lincomycin, spectinomycin cocktail developed in the mid 80’s was studied to control specific organisms – static effects to less that 100 cfu . See 3 papers in Theriogenology vol 29; pp 577- 591, 593-608 and 609-614. Some bacteria may not be statically controlled by these antibiotics and may cause reduced fertility.

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