Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
J Dairy Sci. 2013 Aug;96(8):5324-32. doi: 10.3168/jds.2012-6221. Epub 2013 May 22.
The objective of this study was to investigate how useful data from automatic milking systems used in commercial herds are for genetic analysis of milkability traits. Data were available from 4,968 Swedish Holstein and Swedish Red cows over a span of 5 yr (2004-2009) from 19 herds. The analyzed milkability traits were average flow rate, box time, milking interval, and number of milkings per day. Variance components were estimated for genetic, permanent environmental, and residual effects in first and later (second and third) lactations, and were used for estimation of heritabilities and repeatablilites. The experiences of the data quality and editing procedures showed that almost half of the data and about a quarter of the cows had to be excluded from the analyses due to incomplete or inconsistent information. However, much more data are available than is needed for accurate genetic parameter estimations. For the genetic analysis, a repeatability animal model was used that included the fixed effects of herd, year and season, lactation month, and milk yield. The repeatability coefficients were at a high level: highest for average flow rate, with estimates between 0.8 and 0.9. The estimated heritability coefficients were in the range of 0.37 to 0.48, 0.21 to 0.44, 0.09 to 0.26, and 0.02 to 0.07 for average flow rate, box time, milking interval, and number of milkings, respectively. The results from the present study unraveled large genetic variation in milkability traits. The genetic parameter estimates were well in agreement with previous studies of milkability, which proves the feasibility of using data from automatic milking systems for genetic analysis.
本研究旨在探讨商业牛群中使用的自动挤奶系统的数据对于奶用性状遗传分析的有用性。该研究的数据来自于 19 个牛群中 4968 头瑞典荷斯坦奶牛和瑞典红牛，跨度为 5 年（2004-2009 年）。分析的奶用性状包括平均流速、挤奶时间、挤奶间隔和每日挤奶次数。遗传、永久环境和残余效应的方差分量在第一和后续（第二和第三）泌乳期进行了估计，并用于估计遗传力和重复性。数据质量和编辑程序的经验表明，由于信息不完整或不一致，近一半的数据和大约四分之一的奶牛必须从分析中排除。然而，可用于准确遗传参数估计的数据要多得多。对于遗传分析，使用了一种重复动物模型，该模型包括了牛群、年份和季节、泌乳月份和产奶量的固定效应。重复性系数很高：平均流速最高，估计值在 0.8 到 0.9 之间。估计的遗传力系数在 0.37 到 0.48、0.21 到 0.44、0.09 到 0.26 和 0.02 到 0.07 之间，分别为平均流速、挤奶时间、挤奶间隔和挤奶次数。本研究的结果揭示了奶用性状存在较大的遗传变异。遗传参数估计与先前的奶用性状研究非常吻合，证明了使用自动挤奶系统数据进行遗传分析的可行性。
