Possibilities for a specific breeding program for organic dairy production

摘要

Organic dairy production differs from conventionaldairy production in many aspects. However, breedingprograms for the 2 production systems are the samein most countries. Breeding goals (BG) might be differentfor the 2 production systems and genotype ×environment interaction may exist between organicand conventional dairy production, both of which havean effect on genetic gain in different breeding strategies.Other aspects also need to be considered, suchas the application of multiple ovulation and embryotransfer (MOET), which is not allowed in organic dairyproduction. The general aim of this research was toassess different environment-specific breeding strategiesfor organic dairy production. The specific aim was tostudy differences in BG weights and include the effectof genotype × environment interaction, MOET, andthe selection of breeding bulls from the conventionalenvironment. Different scenarios were simulated. In thecurrent scenario, the present-day situation for dairy productionin Denmark was emulated as much as possible.The BG was based on a conventional dairy productionsystem, MOET was applied in both environments, andconventional bulls could be selected as breeding bullsin the organic environment. Four alternative scenarioswere simulated, all with a specific organic BG in theorganic breeding program but differences in the usageof MOET and the selection of conventional bulls asbreeding bulls. Implementation of a specific BG in organicdairy production slightly increased genetic gainin the aggregate genotype compared with the breedingprogram that is currently implemented in organic dairyproduction. Not using embryo transfer or only selectingbreeding bulls from the organic environment decreasedgenetic gain in the aggregate genotype by as much as24%. However, the use of embryo transfer is debatablebecause this is not allowed according to current regulationsfor organic dairy production. Assessing geneticgain on trait levels showed that a significant increasefor functional traits was possible compared with thecurrent breeding program in the organic environmentwithout a decrease in genetic gain in the aggregategenotype. This difference on trait level was even morepresent when selection of conventional bulls as breedingbulls in the organic environment was not possible. Thisfinding is very relevant when breeding for the desiredcow in organic dairy production.