The potential of gender-sorted semen for improving dairy farm profitability, efficiency and genetic gain in New Zealand : A dissertation submitted in partial fulfillment of the requirement for the Degree of BAgrSc (Honours)

Contents of CD to be added. Pagination discrepancy - vii, 8-69, 69 pages in total

Gender sorted semen, or "sexed-semen" is a new biotechnology available in New Zealand. There are potential benefits associated with its use on dairy farms, including a greater number of heifer calves born allowing for increased genetic selection pressure for herd replacements, increased income from sale of surplus heifer stock, improvements in animal welfare and improvements in the efficiency of milk production. The disadvantages of the technology include the reduced conception rate and final calving rate of cows, as well as the increased insemination costs and lower average genetic merit of sires available. A bio-economic model is presented that enables comparison of four sexed-semen scenarios in five simulated herds that were based on animals from the Lincoln University Dairy Farm. This enabled analysis of the costs and benefits resulting from the use of sexed­ semen, as well as variation between herds and sensitivities. The marginal net present value outcomes were; -$284 for a frozen sexed-semen scenario, $1,056 for a fresh sexed-semen scenario, $353 for the use of sexed-semen sorted to 75% purity and $5,096 for a scenario based on estimates of parameters possible with an improved technology. The results indicate the unreliability of net financial gain through using current gender-sorted semen technology, especially with the use of frozen sexed­ semen. The non-financial benefits and limitations of the products are discussed, and is was concluded that sexed-semen is a breeding technology that allows more flexibility to the management of dairy farms, especially if problems due to sperm viability and sperm wastage during processing can be resolved. If some of the challenges can be addressed, the benefits for milk producers and the dairy industry are substantial.