Fraga Angelina Bossi, de Lima Silva Fabiane, Hongyu Kuang, Da Silva Santos Darlim, Murphy Thomas Wayne, Lopes Fernando Brito
Centro de Ciências Agrárias, Universidade Federal de Alagoas, BR 104 Norte, Km 85, 57.100-000, Rio Largo, AL, Brazil.
Departamento de Estatística, Universidade Federal de Mato Grosso, 78.060-900, Cuiabá, MT, Brazil.
Trop Anim Health Prod. 2016 Mar;48(3):533-8. doi: 10.1007/s11250-015-0985-2. Epub 2015 Dec 30.
The objective of this research was to try to unveil the relationship between production traits and genotypic proportions of crossbred dairy cattle using principal component analysis (PCA) and cluster analysis. The herd consists of crossbred animals of Holstein (H) and Zebu (Z) (Gir and Guzerat) in different genotypic proportions; the composition of which varies from 12.5 to 100.0 % of the genetic group H. For this study, 834 milk production records from 257 cows from the years 1997 to 2014 were analyzed. The animals were all managed at a farm located in northeastern Brazil. The variables in the PCA were total milk yield per lactation (MY), milk yield adjusted to 305 days (MY305), lactation length (LL), and proportion of H and Z breeding. This analysis reduced the size of the sample space from the original five variables to two principal components (PCs) that together explained 89.4 % of the total variation. MY, MY305, LL, and genotypic proportion of H all contributed positively to PC1. The genotypic proportion of Z contributed negatively, which established a contrast between H and Z. Further cluster analysis identified two distinct groups when considering production performance and genotype of the animals. The high-performance group was predominantly Holstein breeding, while the lower performing group consisted mostly of Zebu. Under the environmental and management conditions in which this research was conducted, the best performances for the traits considered were achieved from cows whose genotypic proportion was between 38.0 and 94.0 % Holstein breeding.
本研究的目的是尝试运用主成分分析（PCA）和聚类分析揭示杂交奶牛生产性状与基因型比例之间的关系。该牛群由不同基因型比例的荷斯坦（H）和瘤牛（Z）（吉尔牛和古泽拉特牛）杂交动物组成；其组成中遗传群体H的比例从12.5%到100.0%不等。本研究分析了1997年至2014年来自257头奶牛的834条产奶记录。这些动物均在巴西东北部的一个农场饲养管理。主成分分析中的变量包括每个泌乳期的总产奶量（MY）、校正到305天的产奶量（MY305）、泌乳期长度（LL）以及H和Z的育种比例。该分析将样本空间的规模从原来的五个变量缩减为两个主成分（PC），这两个主成分共同解释了总变异的89.4%。MY、MY305、LL以及H的基因型比例对主成分1均有正向贡献。Z的基因型比例有负向贡献，这在H和Z之间形成了对比。进一步的聚类分析在考虑动物的生产性能和基因型时确定了两个不同的组。高性能组主要是荷斯坦育种，而低性能组主要由瘤牛组成。在本研究开展的环境和管理条件下，对于所考虑的性状，基因型比例在38.0%至94.0%荷斯坦育种之间的奶牛表现最佳。
