Many boar studs currently pre-extend semen with the thought of reducing cold shock. The most important factors influencing sperm function include collection temperature, storage temperature, and the suspension medium. When spermatozoa are cooled too abruptly from body temperature to less than 15 degrees C cold shock can occur, which may reduce sperm viability. Semen should be extended as soon as possible after collection from the boar. Pre-extension is also thought to provide a more gradual osmotic change using a small amount (100ml) of extender and following up with full extension. Pre-extending semen also quickly exposes the raw ejaculate to antibiotics. Bacteria are a normal component of the boar ejaculate, and have been reported to range in concentrations of up to 10~9 cfu/ml. Pre-extension, however is time consuming in the boar stud. The possibility of full extension in a single step would save time and the potential for error since the semen is handled once instead of two separate times. Theaim of this study was to determine if there was a significant difference in reproductive performance between sows that were inseminated with pre-extended semen compared to those that were inseminated with semen that was not pre-extended.
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