Alternative to antibiotics in bull semen extenders to reduce antimicrobial resistance: an artificial insemination trial
Project overview
Participants
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Short summary
The purpose of the project is to conduct an artificial insemination trial using bull semen prepared by Single Layer Centrifugation through a low density colloid. This novel technique separates spermatozoa from bacteria in semen but its effect on fertility in inseminated cows is unknown.
General background
Antimicrobial resistance (AMR) is proving to be a major global challenge. Since bacteria and genes for AMR can be passed between different species, e.g. between animals and humans, AMR is technically a zoonosis. Although veterinarians are attempting to reduce antibiotic usage in food-producing animals, such as cattle, livestock production is still one of the major users of antibiotics. A non-therapeutic use of antibiotics is in semen extenders used to prepare semen for artificial insemination (AI), a technology that is widely used for breeding cattle. Almost all ejaculates contain some bacteria because the mucosa of the distal reproductive tract becomes colonised by bacteria from the skin and the environment, and are transferred to the semen during ejaculation. The extenders added to support sperm survival during preservation provide nutrients for bacteria. These bacteria cause sperm quality to deteriorate by producing metabolic byproducts and toxins, and may cause disease in inseminated females.
A potential novel alternative to antibiotics
Our team has tested colloid centrifugation of semen to separate spermatozoa from bacteria as a possible alternative to the addition of antibiotics to inhibit bacterial growth in semen samples. The results were very promising, since the method (Single Layer Centrifugation through a low density colloid) was able to reduce the bacterial load in bull semen considerably. Some bacterial species could be completely removed by this method, and others were reduced.
The present project
The next step is to investigate what happens in the reproductive tract of the cow if semen doses containing a small number of viable bacteria are inseminated. In theory, these bacteria should not constitute a problem for the cow, since the insemination doses that are currently in use may contain viable bacteria despite the presence of antibiotics.
Our hypothesis is that bull semen prepared by Single Layer Centrifugation through a low density colloid can be used for insemination without a deleterious effect on the cow and without affecting her future fertility.