De Boer I J, Van Arendonk J A
Department of Animal Breeding, Wageningen Agricultural University, The Netherlands.
J Dairy Sci. 1994 Dec;77(12):3691-703. doi: 10.3168/jds.S0022-0302(94)77314-8.
Use of cloned embryos from desirable genotypes (commercial clone lines) enables faster dissemination of superior genetics to dairy producers. Under optimal purchasing strategies of milk producers, the annual proportion of replacement cows from commercial clone lines indicates the market share of cloned embryos compared with semen. Relevant factors affecting this market share were studied. To produce the next generation of commercial cows, the nucleus provided semen from the best sire and cloned embryos from the best female genotype, were selected for a trait associated with lactation. A commercial cow was inseminated if net returns from her expected offspring were higher than net returns from an expected contemporary clone. Net returns equaled net milk returns minus the costs required to breed an expected offspring. If not inseminated, a cow could be used for implantation of a cloned embryo. An increase in the genetic difference between cloned embryos and semen or in the annual additive genetic response achieved in the nucleus increased market share of cloned embryos. Market share decreased as the difference in costs required to breed an offspring from AI or implantation increased. In addition, market share was affected by characteristics of the commercial cow population before the introduction of clones.
使用来自优良基因型的克隆胚胎（商业克隆系）能够更快地将优良基因传播给奶牛养殖户。在牛奶生产商的最优采购策略下，来自商业克隆系的后备奶牛的年度比例表明了克隆胚胎相对于精液的市场份额。研究了影响这一市场份额的相关因素。为了培育下一代商业奶牛，细胞核提供的精液来自最佳种公牛，克隆胚胎来自最佳雌性基因型，这些都针对与泌乳相关的性状进行了选择。如果一头商业奶牛预期后代的净收益高于预期当代克隆体的净收益，就对其进行授精。净收益等于净牛奶收益减去培育预期后代所需的成本。如果不进行授精，奶牛可用于植入克隆胚胎。克隆胚胎与精液之间遗传差异的增加或细胞核中实现的年度加性遗传反应的增加会提高克隆胚胎的市场份额。随着通过人工授精或植入培育后代所需成本差异的增加，市场份额会下降。此外，市场份额还受到引入克隆体之前商业奶牛群体特征的影响。
