Wirth Anna, Duda Jürgen, Distl Ottmar
Institute of Animal Breeding and Genetics, University of Veterinary Medicine Hannover (Foundation), 30559 Hannover, Germany.
Landeskuratorium der Erzeugerringe für Tierische Veredelung in Bayern e.V. (LKV), 80687 München, Germany.
Animals (Basel). 2023 Aug 30;13(17):2765. doi: 10.3390/ani13172765.
A recent study on the population structure of the German Brown population found increasing levels of classical and ancestral inbreeding coefficients. Thus, the aim of this study was to determine the effects of inbreeding depression and purging on longevity traits using classical and ancestral inbreeding coefficients according to Kalinowski (2002) (F, F), Ballou (1997) (F), and Baumung (2015) (Ahc). For this purpose, uncensored data of 480,440 cows born between 1990 and 2001 were available. We analyzed 17 longevity traits, including herd life, length of productive life, number of calvings, lifetime and effective lifetime production for milk, fat, and protein yield, the survival to the 2nd, 4th, 6th, 8th, and 10th lactation number, and the culling frequencies due to infertility, or udder and foot and leg problems. Inbreeding depression was significant and negative for all traits but for culling due to udder and to foot and leg problems. When expressed in percentages of genetic standard deviations, inbreeding depression per 1% increase in inbreeding was -3.61 to -10.98%, -2.42 to -2.99%, -2.21 to -4.58%, and 5.13% for lifetime production traits, lifetime traits, survival rates, and culling due to infertility, respectively. Heterosis and recombination effects due to US Brown Swiss genes were positive and counteracted inbreeding depression. The effects of F were not significantly different from zero, while F had negative effects on lifetime and lifetime production traits. Similarly, the interaction of F with F was significantly negative. Thus, purging effects could not be shown for longevity traits in German Brown. A possible explanation may be seen in the breed history of the German Brown, that through the introgression of US Brown Swiss bulls ancestral inbreeding increased and longevity decreased. Our results show, that reducing a further increase in inbreeding in mating plans is advisable to prevent a further decline in longevity due to inbreeding depression, as purging effects were very unlikely in this population.
最近一项关于德国褐牛种群结构的研究发现，经典近交系数和祖先近交系数水平不断上升。因此，本研究的目的是根据Kalinowski（2002年）（F、F）、Ballou（1997年）（F）和Baumung（2015年）（Ahc）的方法，使用经典近交系数和祖先近交系数来确定近交衰退和清除对长寿性状的影响。为此，可获得1990年至2001年间出生的480440头奶牛的未删失数据。我们分析了17个长寿性状，包括牛群生活期、生产寿命长度、产犊次数、牛奶、脂肪和蛋白质产量的终生和有效终生产量、第2、4、6、8和10胎次的存活情况，以及因不育、乳房和蹄腿问题导致的淘汰频率。除了因乳房和蹄腿问题导致的淘汰外，近交衰退对所有性状均具有显著的负面影响。以遗传标准差的百分比表示，近交每增加1%，终生生产性状、终生性状、存活率和因不育导致的淘汰的近交衰退分别为-3.61%至-10.98%、-2.42%至-2.99%、-2.21%至-4.58%和5.13%。美国褐瑞士牛基因引起的杂种优势和重组效应为正，并抵消了近交衰退。F的影响与零无显著差异，而F对终生和终生生产性状有负面影响。同样，F与F的相互作用显著为负。因此，在德国褐牛中未发现长寿性状的清除效应。一个可能的解释可能在于德国褐牛的品种历史，即通过引入美国褐瑞士公牛，祖先近交增加，寿命缩短。我们的结果表明，由于该群体中清除效应极不可能发生，因此建议在配种计划中减少近交的进一步增加，以防止因近交衰退导致寿命进一步下降。
