Contaminant toxicity of concern for boars and semen used in assisted reproduction programs

The commercial swine industry utilizes artificial insemination (AI) in their breeding programs. With this assisted reproductive technology, the process starts by obtaining fresh ejaculates from desirable boars who are housed in a dedicated facility (i.e., stud) that also contains a clean-room laboratory where semen quality is assessed and then ejaculates processed into AI doses. In concert with AI adoption, disruptions in sow herd reproductive performance have been traced back to contributions made from the boar stud. Through field investigations and research, several extrinsic contaminants have been identified that impact semen quality either at the boar or AI-dose level. These contaminants can be categorized as either biological or chemical in origin, eliciting reprotoxic outcomes at the boar level and/or spermatotoxicity at the AI-dose level. Biological contaminants include multiple genera of primarily opportunistic microbes (i.e., bacteria, fungi), along with their secondary metabolites (e.g., endotoxins, exotoxins, mycotoxins). Chemical contaminants appear to originate from products used at the stud, and include cleaning agent/disinfectant residues, leachates from gloves and plastics, semen extender impurities, purified and drinking water impurities, and pesticides (i.e., biocides, fungicides, herbicides, insecticides, wood preservatives). In conclusion, contaminants are a real and constant threat to the health and productivity of a stud, and have caused significant reproductive and economic losses in the swine industry. The knowledge gained in recognizing the types and sources of contaminants provides a solid foundation for the development and implementation of pro-active strategies that mitigate risk to the industry.