1Department of Agricultural Sciences,University of Helsinki,FI-00014 Helsinki,Finland.
2Lattec I/S,Slangerupgade 69,3400 Hillerod,Denmark.
Animal. 2019 Feb;13(2):248-255. doi: 10.1017/S1751731118001386. Epub 2018 Jun 29.
High-yielding cows may suffer from negative energy balance during early lactation, which can lead to ketosis and delayed ability of returning to cyclicity after calving. Fast recovery after calving is essential when breeding for improved fertility. Traditionally used fertility traits, such as the interval from calving to first insemination (CFI), have low heritabilities and are highly influenced by management decisions. Herd Navigator™ management program samples and analyses milk progesterone and β-hydroxybutyrate (BHB) automatically during milking. In this study, the genetic parameters of endocrine fertility traits (measured from milk progesterone) and hyperketonemia (measured from milk BHB) in early lactation were evaluated and compared with traditional fertility traits (CFI, interval from calving to the last insemination and interval from first to last insemination) and the milk yield in red dairy cattle herds in Finland. Data included observations from 14 farms from 2014 to 2017. Data were analyzed with linear animal models using DMU software and analyses were done for first parity cows. Heritability estimates for traditional fertility traits were low and varied between 0.03 and 0.07. Estimated heritabilities for endocrine fertility traits (interval from calving to the first heat (CFH) and commencement of luteal activity (C-LA)) were higher than for traditional fertility traits (0.19 to 0.33). Five slightly different hyperketonemia traits divided into two or three classes were studied. Linear model heritability estimates for hyperketonemia traits were low, however, when the threshold model was used for binary traits the estimates became slightly higher (0.07 to 0.15). Genetic correlation between CFH and C-LA for first parity cows was high (0.97) as expected since traits are quite similar. Moderate genetic correlations (0.47 to 0.52) were found between the endocrine fertility traits and early lactation milk yield. Results suggest that the data on endocrine fertility traits measured by automatic systems is a promising tool for improving fertility, specifically when more data is available. For hyperketonemia traits, dividing values into three classes instead of two seemed to work better. Based on the current study and previous studies, where higher heritabilities have been found for milk BHB traits than for clinical ketosis, milk BHB traits are a promising indicator trait for resistance to ketosis and should be studied more. It is important that this kind of data from automatic devices is made available to recording and breeding organizations in the future.
高产奶牛在泌乳早期可能会出现负能量平衡，这可能导致酮病和产后发情恢复延迟。在提高繁殖力方面，产后快速恢复至关重要。传统上使用的繁殖力性状，如产后至首次配种的间隔（CFI），遗传力低，受管理决策的影响很大。Herd Navigator™管理程序在挤奶时自动采样和分析牛奶孕酮和β-羟丁酸（BHB）。本研究评估和比较了泌乳早期内分泌繁殖力性状（测量牛奶孕酮）和高酮血症（测量牛奶 BHB）的遗传参数，以及传统繁殖力性状（CFI、产后至最后一次配种的间隔和首次至最后一次配种的间隔）和芬兰红奶牛群的产奶量。数据包括 2014 年至 2017 年 14 个农场的观测结果。使用 DMU 软件，通过线性动物模型对数据进行分析，对第一胎次奶牛进行分析。传统繁殖力性状的遗传力估计值较低，在 0.03 至 0.07 之间变化。内分泌繁殖力性状（产后至第一次发情（CFH）和黄体活动开始（C-LA）的间隔）的遗传力估计值高于传统繁殖力性状（0.19 至 0.33）。研究了五个略有不同的高酮血症性状，分为两类或三类。高酮血症性状的线性模型遗传力估计值较低，然而，当使用二元性状的阈值模型时，估计值略有升高（0.07 至 0.15）。第一胎次奶牛 CFH 和 C-LA 之间的遗传相关性很高（0.97），这是意料之中的，因为这些性状非常相似。内分泌繁殖力性状与泌乳早期产奶量之间存在中度遗传相关性（0.47 至 0.52）。研究结果表明，自动系统测量的内分泌繁殖力性状数据是提高繁殖力的一种有前途的工具，特别是当有更多数据可用时。对于高酮血症性状，将值分为三类而不是两类似乎效果更好。基于当前研究和之前的研究，其中牛奶 BHB 性状的遗传力高于临床酮病，牛奶 BHB 性状是对酮病抵抗力的一个有前途的指示性状，应进一步研究。将来，重要的是要使自动设备的这种数据可用于记录和繁殖组织。
