Gernand E, König S
Thuringian State Institute of Agriculture, 07743 Jena, Germany.
Department of Animal Breeding, University of Kassel, 37213 Witzenhausen, Germany.
J Dairy Sci. 2014 Sep;97(9):5872-9. doi: 10.3168/jds.2013-7612. Epub 2014 Jul 2.
The aim of the present study was to infer daily genetic relationships between the selected claw disorders digital dermatitis, sole ulcer (SU), and interdigital hyperplasia (IH) and protein yield and the udder health indicator somatic cell score (SCS). Data were from 26,651 Holstein cows kept in 15 selected large-scale herds located in the region of Thuringia in the eastern part of Germany. Herds are characterized by organized data recording for novel health traits, and for the present study, claw disorders from the years 2008 to 2012 were used. A longitudinal and binary health data structure was created by assigning claw disorders to adjacent official test days. No entry of a claw disorder within a given interval of approximately 30 d implied a score of 0 (healthy), and otherwise, a score of 1 (diseased). Threshold random regression models (RRM) were applied to binary health data, and linear RRM to Gaussian-distributed protein yield and SCS. Genetic correlations between protein yield and SCS for identical days in milk (DIM) only revealed a tendency for genetic antagonisms between DIM 40 and DIM 180, with a maximal genetic correlation (rg) of 0.14 at DIM 100. With regard to protein yield and claw disorders, the largest and moderate values of rg (~0.30), indicating a genetic antagonism between productivity and claw health, were found when correlating protein yield from DIM 300 with SU from DIM 160. Especially for SU and protein yield, time-lagged relationships were more pronounced than genetic relationships from the same test days. Genetic correlations between IH and protein yield were favorable and negative from calving to DIM 300. Generally, on the genetic scale, we found heterogeneous associations between protein yield and claw disorders (i.e., different rg at identical test days for different claw disorders, and also an alteration of rg for identical traits at different DIM). The SCS measured at d 20, 160, and 300 was genetically positively correlated with SU over the whole trajectory of 365 d, indicating a common genetic background for claw and udder health. A maximal value of 0.36 was found for the rg between SCS from d 300 and SU early in lactation. Additionally, a recursive effect was observed (i.e., rg=0.26 between SCS from d 20 and SU from d 340). Genetic correlations between SCS and IH, and between SCS and digital dermatitis, were close to zero and partly negative during lactation. Results showed the feasibility of threshold RRM applications to binary claw health data, and a changing genetic background in the course of lactation. From a practical perspective, and with regard to the herds used in this study, continuation of breeding on productivity will have different effects on incidences of different claw disorders, with the highest susceptibility to SU.
本研究的目的是推断所选蹄部疾病（数字皮炎、蹄底溃疡（SU）和指间增生（IH））与产奶量以及乳房健康指标体细胞评分（SCS）之间的每日遗传关系。数据来自德国东部图林根地区15个选定的大型牛群中饲养的26651头荷斯坦奶牛。这些牛群的特点是对新的健康性状进行有组织的数据记录，在本研究中，使用了2008年至2012年的蹄部疾病数据。通过将蹄部疾病分配到相邻的官方检测日，创建了纵向和二元健康数据结构。在大约30天的给定间隔内没有蹄部疾病记录意味着评分为0（健康），否则评分为1（患病）。阈值随机回归模型（RRM）应用于二元健康数据，线性RRM应用于高斯分布的产奶量和SCS。仅在相同的泌乳天数（DIM）下，产奶量与SCS之间的遗传相关性仅显示在DIM 40至DIM 180之间存在遗传拮抗趋势，在DIM 100时最大遗传相关性（rg）为0.14。关于产奶量和蹄部疾病，当将DIM 300的产奶量与DIM 160的SU相关联时，发现rg的最大值和中等值（约0.30），表明生产力与蹄部健康之间存在遗传拮抗。特别是对于SU和产奶量，时滞关系比同一检测日的遗传关系更明显。从产犊到DIM 300，IH与产奶量之间的遗传相关性是有利的且为负。一般来说，在遗传尺度上，我们发现产奶量与蹄部疾病之间存在异质性关联（即不同蹄部疾病在相同检测日的rg不同，以及相同性状在不同DIM时rg的变化）。在第20、160和300天测量的SCS在整个365天的轨迹上与SU呈正遗传相关，表明蹄部和乳房健康具有共同的遗传背景。在泌乳早期，DIM 300的SCS与SU之间的rg最大值为0.36。此外，还观察到一种递归效应（即第20天的SCS与第340天的SU之间的rg = 0.26）。在泌乳期间，SCS与IH之间以及SCS与数字皮炎之间的遗传相关性接近于零，部分为负。结果表明阈值RRM应用于二元蹄部健康数据的可行性，以及泌乳过程中遗传背景的变化。从实际角度来看，就本研究中使用的牛群而言，继续进行生产力育种将对不同蹄部疾病的发病率产生不同影响，其中SU的易感性最高。
