Selection in local dual-purpose breeds requires great carefulness because of the need to preserve peculiar traits and also guarantee the positive genetic progress for milk and beef production to maintain economic competitiveness. A specific breeding plan accounting for milk, beef, and functional traits is required by breeders of the Alpine Grey cattle (AG), a local dual-purpose breed of the Italian Alps. Hereditability and genetic correlations among all traits have been analyzed for this purpose. After that, different selection indexes were proposed to identify the most suitable for this breed. Firstly, a genetic parameters analysis was carried out with different datasets. The milk dataset contained 406,918 test day records of milk, protein, and fat yields and somatic cells (expressed as SCS). The beef dataset included performance test data conducted on 749 young bulls. Average daily gain, in vivo estimated carcass yields, and carcass conformation (SEUROP) were the phenotypes obtained from the performance tests. The morphological dataset included 21 linear type evaluations of 11,320 first party cows. Linear type traits were aggregated through factor analysis and three factors were retained, while head typicality (HT) and rear muscularity (RM) were analyzed as single traits. Heritability estimates (h²) for milk traits ranged from 0.125 to 0.219. Analysis of beef traits showed h² greater than milk traits, ranging from 0.282 to 0.501. Type traits showed a medium value of h² ranging from 0.238 to 0.374. Regarding genetic correlation, SCS and milk traits were strongly positively correlated. Milk traits had a negative genetic correlation with the factor accounting for udder conformations (−0.40) and with all performance test traits and RM. These latter traits showed also a negative genetic correlation with udder volume (−0.28). The HT and the factor accounting for rear legs traits were not correlated with milk traits, but negatively correlated with beef traits (−0.32 with RM). We argue that the consequence of these results is that the use of the current selection index, which is mainly focused on milk attitude, will lead to a deterioration of all other traits. In this study, we propose more appropriate selection indexes that account for genetic relationships among traits, including functional traits.

中文翻译：

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高山灰牛品种由于拮抗乳，牛肉和形态性状的不同组合而产生的选择响应

在选择当地两用品种时需要非常谨慎，因为需要保留独特的性状，还需要保证牛奶和牛肉生产的积极遗传进展，以保持经济竞争力。阿尔卑斯灰牛（AG）是意大利阿尔卑斯山的本地双重用途品种，其育种者需要针对牛奶，牛肉和功能性状的特定育种计划。为此目的，分析了所有性状之间的遗传性和遗传相关性。此后，提出了不同的选择指标来确定最适合该品种的品种。首先，利用不同的数据集进行了遗传参数分析。牛奶数据集包含406,918个测试日记录的牛奶，蛋白质和脂肪产量以及体细胞（表示为SCS）。牛肉数据集包括对749头小公牛进行的性能测试数据。平均日增重，体内估计car体产量和car体构象（SEUROP）是从性能测试中获得的表型。形态数据集包括对11,320头母牛的21种线性类型评估。通过因素分析汇总了线性型性状，保留了三个因素，而将头部典型性（HT）和后部肌肉性（RM）作为单个性状进行了分析。遗传力估计值（h 通过因素分析汇总了线性型性状，保留了三个因素，而将头部典型性（HT）和后部肌肉性（RM）作为单个性状进行了分析。遗传力估计值（h 通过因素分析汇总了线性型性状，保留了三个因素，而将头部典型性（HT）和后部肌肉性（RM）作为单个性状进行了分析。遗传力估计值（h²）牛奶性状的范围从0.125到0.219。牛肉性状的分析显示，h ²大于牛奶性状，范围为0.282至0.501。类型性状表现出中等的h ²值范围从0.238到0.374。关于遗传相关性，SCS和牛奶性状之间呈强正相关。牛奶性状与影响乳房构象的因子（−0.40）以及所有性能测试性状和RM呈负相关。后者的这些特性也显示出与乳房体积负相关（-0.28）。HT和解释后腿性状的因素与牛奶性状不相关，而与牛肉性状负相关（RM为−0.32）。我们认为，这些结果的结果是，当前选择指数的使用（主要侧重于牛奶态度）将导致所有其他特征的恶化。在这项研究中，我们提出了更合适的选择指标，以说明性状之间的遗传关系，包括功能性状。