Department of Molecular Biology and Genetics, Center for Quantitative Genetics and Genomics, Aarhus University, 8830 Tjele, Denmark.
Department of Molecular Biology and Genetics, Center for Quantitative Genetics and Genomics, Aarhus University, 8830 Tjele, Denmark.
J Dairy Sci. 2020 Jul;103(7):6332-6345. doi: 10.3168/jds.2019-16900. Epub 2020 Apr 29.
Organic dairy production differs from conventional dairy production in many aspects. However, breeding programs for the 2 production systems are the same in most countries. Breeding goals (BG) might be different for the 2 production systems and genotype × environment interaction may exist between organic and conventional dairy production, both of which have an effect on genetic gain in different breeding strategies. Other aspects also need to be considered, such as the application of multiple ovulation and embryo transfer (MOET), which is not allowed in organic dairy production. The general aim of this research was to assess different environment-specific breeding strategies for organic dairy production. The specific aim was to study differences in BG weights and include the effect of genotype × environment interaction, MOET, and the selection of breeding bulls from the conventional environment. Different scenarios were simulated. In the current scenario, the present-day situation for dairy production in Denmark was emulated as much as possible. The BG was based on a conventional dairy production system, MOET was applied in both environments, and conventional bulls could be selected as breeding bulls in the organic environment. Four alternative scenarios were simulated, all with a specific organic BG in the organic breeding program but differences in the usage of MOET and the selection of conventional bulls as breeding bulls. Implementation of a specific BG in organic dairy production slightly increased genetic gain in the aggregate genotype compared with the breeding program that is currently implemented in organic dairy production. Not using embryo transfer or only selecting breeding bulls from the organic environment decreased genetic gain in the aggregate genotype by as much as 24%. However, the use of embryo transfer is debatable because this is not allowed according to current regulations for organic dairy production. Assessing genetic gain on trait levels showed that a significant increase for functional traits was possible compared with the current breeding program in the organic environment without a decrease in genetic gain in the aggregate genotype. This difference on trait level was even more present when selection of conventional bulls as breeding bulls in the organic environment was not possible. This finding is very relevant when breeding for the desired cow in organic dairy production.
有机奶牛养殖在许多方面与传统奶牛养殖不同。然而，在大多数国家，这两种生产系统的育种计划是相同的。这两种生产系统的育种目标可能不同，并且基因型与环境的互作可能存在于有机和传统奶牛养殖之间，这两者都会对不同的育种策略中的遗传进展产生影响。还需要考虑其他方面，例如多排卵和胚胎移植（MOET）的应用，这在有机奶牛养殖中是不允许的。本研究的总体目标是评估有机奶牛养殖的不同特定环境的育种策略。具体目标是研究不同的育种目标权重差异，并包括基因型与环境互作的影响、MOET 以及从传统环境中选择种公牛的影响。不同的情景进行了模拟。在当前情景中，尽可能模拟了丹麦当前的奶牛养殖情况。该育种目标基于传统的奶牛养殖系统，在两种环境中都应用了 MOET，并且可以在有机环境中选择传统公牛作为种公牛。模拟了四个替代情景，所有情景在有机育种计划中都具有特定的有机育种目标，但在 MOET 的使用和传统公牛作为种公牛的选择方面存在差异。在有机奶牛养殖中实施特定的育种目标会略微增加总体基因型的遗传进展，而不是目前在有机奶牛养殖中实施的育种计划。不使用胚胎移植或仅从有机环境中选择种公牛会使总体基因型的遗传进展减少多达 24%。然而，胚胎移植的使用是有争议的，因为根据当前有机奶牛养殖的规定，这是不允许的。对性状水平的遗传进展评估表明，在有机环境中，与现行育种计划相比，功能性状的遗传进展可以显著提高，而总体基因型的遗传进展不会降低。当在有机环境中不可能选择传统公牛作为种公牛时，这种性状水平的差异更为明显。当在有机奶牛养殖中进行所需奶牛的选育时，这一发现非常重要。
