Callegaro Simone, Tiezzi Francesco, Maltecca Christian, Fabbri Maria Chiara, Bozzi Riccardo
Department of Agriculture, Food, Environment, and Forestry (DAGRI), University of Florence, Florence 50144, Italy.
Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA.
J Anim Sci. 2024 Jan 3;102. doi: 10.1093/jas/skae354.
This study aimed to estimate the genetic parameters of stayability (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, 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 to 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.
本研究旨在使用单步基因组最佳线性无偏预测（ssGBLUP）方法估计意大利夏洛来牛和利木赞肉牛在不同产犊时的留种能力（STAY）的遗传参数，比较高斯线性模型和阈值模型。研究还考察了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。STAY是农场盈利能力的关键性状，定义为母牛在牛群中存活并保持生产能力直至确定年龄的概率。我们评估了从第二次到第三次产犊及后续间隔的STAY（例如，STAY23、STAY78），以及两个繁殖力性状和几个体型性状。数据分别包括来自2471个至1774个牛群的47362头利木赞母牛和9174头夏洛来母牛，它们出生于1977年至2023年之间。使用ssGBLUP对单变量阈值和高斯线性动物模型进行分析，以估计STAY性状（STAY2至STAY8）的遗传参数。此外，使用双变量模型估计STAY与繁殖力和体型性状之间的遗传相关性。对于利木赞牛，使用高斯线性模型和阈值模型时，STAY的遗传力分别为0.13至0.11和0.21至0.14；对于夏洛来牛，分别为0.14至0.11和0.21至0.19。观察到基于STAY性状对基因分型公牛的显著重新排名，特别是与早期产犊（STAY3）相比，更晚产犊（STAY8）时更为明显，这表明STAY性状在遗传上是不同的。利木赞牛的STAY与体型性状之间的遗传相关性为正。在夏洛来牛中，许多性状不相关，但一些体型性状显示出正相关，除了臀部凸度与STAY呈负相关。总之，STAY的遗传力估计表明，在利木赞牛和夏洛来牛群中提高长寿的遗传改良是可行的。选择在早期和晚期产犊时STAY的基因组育种值持续较高的公牛，突出了长期长寿的重要性。遗传相关性表明，基于体型性状的选择可以通过提高利木赞牛的母牛恢复力来提高牛群的存活率。而对于夏洛来牛，一些体型性状与STAY呈正相关，而臀部凸度呈负相关，这可能会影响长寿。
