Olynk N J, Wolf C A
Department of Agricultural Economics, Michigan State University, East Lansing 48824, USA.
J Dairy Sci. 2007 May;90(5):2569-76. doi: 10.3168/jds.2006-460.
Sexed semen has been a long-anticipated tool for dairy farmers to obtain more heifer calves, but challenges exist for integrating sexed semen into commercial dairy farm reproduction programs. The decreased conception rates (CR) experienced with sexed semen make virgin heifers better suited for insemination with sexed semen than lactating dairy cows. This research sought to identify when various sexed semen breeding strategies provided higher expected net present value (NPV) than conventional artificial insemination (AI) breeding schemes, indicating which breeding scheme is advisable under various scenarios. Budgets were developed to calculate the expected NPV of various AI breeding strategies incorporating conventional (non-sexed) and sexed semen. In the base budgets, heifer and bull calf values were held constant at $500 and $110, respectively. The percentage of heifers expected to be born after breeding with conventional and sexed semen used was 49.2 and 90%, respectively. Breeding costs per AI were held constant at $15.00 per AI for conventional semen and $45.00 per AI for sexed semen of approximately the same genetic value. Conventional semen CR of 58 and 65% were used, and an AI submission rate was set at 100%. Breeding strategies with sexed semen were assessed for breakeven heifer calf values and sexed semen costs to obtain a NPV equal to that achieved with conventional semen. Breakeven heifer calf values for pure sexed semen strategies with a constant 58 and 65% base CR in which sexed semen achieved 53% of the base CR are $732.11 and $664.26, respectively. Breakeven sexed semen costs per AI of $17.16 and $22.39, compared with $45.00 per AI, were obtained to obtain a NPV equal to that obtained with pure conventional semen for base CR of 58 and 65%, respectively. The strategy employing purely sexed semen, with base CR of both 58 and 65%, yielded a lower NPV than purely conventional semen in all but the best-case scenario in which sexed semen provides 90% of the CR of conventional semen. Other potential advantages of sexed semen that were not quantified in the scenarios include biosecurity-related concerns, decreased dystocia due to increased numbers of heifer calves, and implications for internal herd growth.
性别分选精液一直是奶农期待已久的获取更多母犊牛的工具，但将性别分选精液纳入商业化奶牛场繁殖计划存在挑战。与性别分选精液相关的受孕率（CR）下降，使得初产小母牛比泌乳奶牛更适合用性别分选精液进行授精。本研究旨在确定在何种情况下，各种性别分选精液繁殖策略能提供比传统人工授精（AI）繁殖方案更高的预期净现值（NPV），从而表明在不同情况下哪种繁殖方案更为可取。制定了预算以计算纳入传统（非性别分选）和性别分选精液的各种AI繁殖策略的预期NPV。在基础预算中，母犊牛和公犊牛的价值分别保持在500美元和110美元不变。使用传统精液和性别分选精液配种后预期出生的小母牛百分比分别为49.2%和90%。每次AI的配种成本对于遗传价值大致相同的传统精液保持在每次AI 15.00美元，对于性别分选精液保持在每次AI 45.00美元。采用传统精液的受孕率分别为58%和65%，且AI提交率设定为100%。评估了使用性别分选精液的繁殖策略的盈亏平衡母犊牛价值和性别分选精液成本，以获得与传统精液相同的NPV。在基础受孕率为58%和65%且性别分选精液达到基础受孕率的53%的纯性别分选精液策略中，盈亏平衡母犊牛价值分别为732.11美元和664.26美元。为了获得与基础受孕率为58%和65%的纯传统精液相同的NPV，每次AI的盈亏平衡性别分选精液成本分别为17.16美元和22.39美元，而每次AI为45.00美元。在基础受孕率为58%和65%的情况下，除了性别分选精液提供传统精液受孕率90%的最佳情况外，采用纯性别分选精液的策略产生的NPV低于纯传统精液。在这些情况中未量化的性别分选精液的其他潜在优势包括与生物安全相关的问题、由于母犊牛数量增加导致难产减少以及对牛群内部增长的影响。
