Department of Animal Sciences, University of Florida, Gainesville 32611.
Department of Animal Sciences, University of Florida, Gainesville 32611.
J Dairy Sci. 2017 Jul;100(7):5729-5745. doi: 10.3168/jds.2016-11979. Epub 2017 Apr 27.
The objective of this study was to implement an in vitro-produced embryo transfer (IVP-ET) system in an existing stochastic dynamic dairy simulation model with multitrait genetics to evaluate the genetic, technical, and financial performance of a dairy herd implementing an exclusive IVP-ET or artificial insemination (AI) system. In the AI system, sexed semen was used on the genetically best heifers only. In the IVP-ET system, all of the animals in the herd were impregnated with female sexed embryos created through in vitro fertilization of oocytes collected from animals of superior genetics for different traits of interest. Each donor was assumed to yield on average 4.25 transferable embryos per collection. The remaining animals in the herd were used as recipients and received either a fresh embryo or a frozen embryo when fresh embryos were not available. Selection of donors was random or based on the greatest estimated breeding value (EBV) of lifetime net merit (NM$), milk yield, or daughter pregnancy rate. For both the IVP-ET and AI systems, culling of surplus heifer calves not needed to replace culled cows was based on the lowest EBV for the same traits. A herd of 1,000 milking cows was simulated 15 yr over time after the start of the IVP-ET system. The default cost to produce and transfer 1 embryo was set at $165. Prices of fresh embryos at which an exclusive IVP-ET system financially breaks even with the comparable AI system in yr 15 and for an investment period of 15 yr were also estimated. More surplus heifer calves were sold from the IVP-ET systems than from the comparable AI systems. The surplus calves from the IVP-ET systems were also genetically superior to the surplus calves from the comparable AI systems, which might be reflected in their market value as a premium price. The most profitable scenario among the 4 IVP-ET scenarios in yr 15 was the one in which NM$ was maximized in the herd. This scenario had an additional profit of $8/cow compared with a similar AI scenario that maximized NM$, provided that surplus heifer calves could be sold at a premium price based on the superiority of the EBV of NM$. For the IVP-ET system to be at least as profitable as the comparable AI system during a 15-yr investment period, the surplus calves from the IVP-ET system needed to be sold at the premium prices. The break-even price of fresh embryos was estimated to be $84 for the exclusive IVP-ET system. This resulted in the same profit as the AI system, which maximized NM$ for a 15-yr investment period and in which heifer calves were sold at a premium price.
本研究旨在将一个具有多性状遗传的现有的随机动态奶牛模拟模型中实施的体外生产胚胎转移（IVP-ET）系统，以评估一个完全实施 IVP-ET 或人工授精（AI）系统的奶牛群的遗传、技术和财务性能。在 AI 系统中，只有具有最佳遗传性状的小母牛使用性别鉴定精液。在 IVP-ET 系统中，通过对具有不同感兴趣性状的优质动物的卵母细胞进行体外受精，对牛群中的所有动物进行妊娠。每个供体平均每批可产生 4.25 个可转移胚胎。牛群中剩余的动物作为受体使用，当没有新鲜胚胎时，它们接受新鲜胚胎或冷冻胚胎。供体的选择是随机的，或者基于终生净效益（NM$）、产奶量或女儿妊娠率的最大估计育种值（EBV）。对于 IVP-ET 和 AI 系统，基于相同性状的最低 EBV，对不需要替换淘汰奶牛的多余小母牛进行淘汰。一个 1000 头泌乳牛的牛群在开始实施 IVP-ET 系统 15 年后进行了模拟。设定生产和转移 1 个胚胎的默认成本为 165 美元。还估计了在第 15 年和 15 年投资期内，独家 IVP-ET 系统与可比 AI 系统实现收支平衡的新鲜胚胎价格。IVP-ET 系统产生的多余小母牛数量多于可比 AI 系统。IVP-ET 系统产生的多余小母牛在遗传上也优于可比 AI 系统，这可能反映在它们作为溢价的市场价值上。在第 15 年的 4 个 IVP-ET 方案中，最盈利的方案是使牛群的 NM$最大化。与最大化 NM$的类似 AI 方案相比，该方案每头牛增加 8 美元的利润，前提是可以根据 NM$的 EBV 溢价出售多余的小母牛。为了使 IVP-ET 系统在 15 年投资期内至少与可比 AI 系统一样有利可图，IVP-ET 系统产生的多余小母牛需要以溢价出售。独家 IVP-ET 系统的新鲜胚胎盈亏平衡价格估计为 84 美元。这与最大化 NM$的 AI 系统的利润相同，后者在 15 年投资期内进行投资，并且小母牛以溢价出售。
