This study aimed to estimate the genetic parameters of Stay-ability (STAY) at different calvings using a single-step genomic best linear unbiased prediction (ssGBLUP) approach, comparing Gaussian-linear and threshold models in Italian Charolais and Limousine beef cattle. It also examined the genetic relationship between STAY and other traits to identify potential indicators of longevity and assessed the impact of STAY selection on economically important traits. Stay-ability, a key trait for farm profitability, is defined as the probability of a cow surviving and remaining productive in the herd until a determined age. We evaluated STAY from the second to third calving and subsequent intervals (e.g., STAY23, STAY78), along with two fertility traits and several conformation traits. Data included 47,362 Limousine cows and 9,174 Charolais cows from 2,471 and 1,774 herds, respectively, born between 1977 and 2023. Analyses were performed fitting univariate threshold and Gaussian-linear animal models to estimate genetic parameters for STAY traits (STAY2 to STAY8) using ssGBLUP. Also, bivariate models were used to estimate genetic correlations between STAY and fertility and conformation traits. Heritabilities for STAY ranged from 0.13 to 0.11 and from 0.21 to 0.14 for Limousine, and from 0.14 to 0.11 and from 0.21 to 0.19 for Charolais, using Gaussian-linear and threshold models, respectively. Significant re-ranking of genotyped sires based on STAY traits was observed, particularly for more distant calvings (STAY8) compared to earlier ones (STAY3), indicating that STAY traits are genetically distinct. Genetic correlations were positive between STAY and conformation traits for Limousine. In Charolais, many traits were uncorrelated, but some conformation traits showed positive correlations, except for rump convexity, which had negative correlations with STAY. In conclusion, the heritability estimates of STAY suggests that genetic improvement for longevity in Limousine and Charolais herds is feasible. Selecting sires with consistently high genomic breeding values for STAY across early and late calvings highlights the importance of long-term longevity. Genetic correlations indicate that selection based on conformation traits could enhance herd survival by improving cow resilience for the Limousine. Instead for the Charolais some conformation traits showed positive correlations with STAY, while rump convexity had negative association, potentially affecting longevity.

中文翻译：

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意大利夏洛莱和利木津品种功能寿命和相关性状的遗传参数


本研究旨在使用单步基因组最佳线性无偏预测 （ssGBLUP） 方法估计不同产犊的生存能力 （STAY） 的遗传参数，比较意大利夏洛莱和利木津肉牛的高斯线性和阈值模型。它还检查了 STAY 与其他性状之间的遗传关系，以确定长寿的潜在指标，并评估 STAY 选择对经济重要性状的影响。保持能力是农场盈利能力的一个关键特征，定义为奶牛在牛群中存活并保持生产力直到确定年龄的概率。我们评估了从第二次到第三次产犊和后续间隔（例如，STAY23、STAY78）的 STAY，以及两个生育性状和几个体型构造性状。数据包括 47,362 头豪华奶牛和 9,174 头夏洛莱奶牛，分别来自 2,471 个和 1,774 个牛群，出生于 1977 年至 2023 年间。拟合单变量阈值和高斯线性动物模型进行分析，以使用 ssGBLUP 估计 STAY 性状 （STAY2 至 STAY8） 的遗传参数。此外，双变量模型用于估计 STAY 与生育力和体型特征之间的遗传相关性。使用高斯线性和阈值模型，豪华轿车的 STAY 遗传力范围为 0.13 至 0.11 和 0.21 至 0.14，夏洛莱的遗传力范围为 0.14 至 0.11 和 0.21 至 0.19。观察到基于 STAY 性状的基因型公牛的显着重新排序，特别是与早期产犊 （STAY3） 相比，更远的产犊 （STAY8） 表明 STAY 性状在遗传上是不同的。STAY 和 Limousine 的体型构象特征之间的遗传相关性呈正相关。 在夏洛莱，许多性状不相关，但一些构象性状呈正相关，但臀部凸度与 STAY 呈负相关。总之，STAY 的遗传力估计表明，Limousine 和 Charolais 牛群的长寿遗传改良是可行的。在产犊早期和晚期选择具有始终高基因组育种值的公牛进行 STAY 突出了长期长寿的重要性。遗传相关性表明，基于体型特征的选择可以通过提高 Limousine 奶牛的适应力来提高牛群存活率。相反，对于夏洛莱犬，一些体型特征与 STAY 呈正相关，而臀部凸起呈负相关，可能影响寿命。