Lowering Sperm Dose Rates in Frozen Semen for Bovine Artificial Breeding
Pitt, C. J. (2007). Lowering Sperm Dose Rates in Frozen Semen for Bovine Artificial Breeding (Thesis, Master of Education (MEd)). The University of Waikato, Hamilton, New Zealand. Retrieved from http://hdl.handle.net/10289/2232
Permanent Research Commons link: http://hdl.handle.net/10289/2232
The New Zealand Dairy industry relies on artificial breeding to produce high geneticmerit replacement stock. Proven bull semen is extended and preserved as eitherambient temperature product or as frozen doses. High fertility is essential to maintainsynchronicity of lactation with the spring surge of grass growth.To improve efficiency in the utilization of the very best bulls producers try to lowersperm dose rates without compromising fertility. Livestock ImprovementCorporation's (LIC) Long Last Liquid ™ (LLL) is most commonly used during thepeak season and is their most important product. However, shortfalls and specificallytargeted matings are met with frozen semen. Lowering sperm dose rates in both liquidand frozen semen maximises the usage of elite sires increasing genetic gain, loweringoverheads and garnering premium prices for the semen producer.A product for improving frozen semen technology was developed whereby a discretequantity of pretreated semen was placed alongside a beneficial post-thawingredilution medium in a standard semen straw. This emulated a larger-scale processdeveloped to freeze semen in times of low demand and redilution into the LLL formfor use as an ambient temperature product. This rediluted product has been proved toenhance semen survival and to allow fertility to be maintained at sperm dose rateslower than the widely accepted standard for frozen semen.The physical packaging of the semen into the industry standard single dose straw in a configuration that separated incompatible components was novel. This configurationwas essential to prevent damage to the sperm during the freezing process from lowsolubility components in the post-thaw redilution medium. Separation between thesemen and diluent within the straw was achieved by the introduction of a gas partitionor air bubble between the two liquids.A large-scale field trial showed that the new product could produce savings of up to25% of the sperm needed for a semen dose to achieve equivalent fertility.Furthermore, the production cost per dose was lowered in comparison to the standardsemen processing system used at LIC.
The University of Waikato
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