Sebastiani Carla, Arcangeli Chiara, Ciullo Marcella, Torricelli Martina, Cinti Giulia, Fisichella Stefano, Biagetti Massimo
Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche-Togo Rosati (IZSUM), Via Salvemini 1, 06126 Perugia, Italy.
R&D Cooperlat, Società Cooperativa Agricola, via Piandelmedico 74, 60035 Jesi (Ancona), Italy.
Animals (Basel). 2020 Feb 5;10(2):252. doi: 10.3390/ani10020252.
The majority of proteins in cow's milk are caseins, which occur in four groups (α-s1, α-s2, β, and k) encoded by different genes (, , , and , respectively). In this study, we focused on the β-casein allele variants A1 and A2 due to their influence on milk's technological characteristics and human health. Digestion of the β-casein variant A1 leads to the formation of β-casomorphin 7 (BCM-7), a bioactive peptide that has been suggested to be a possible cause of various human diseases and associated with low milk digestibility. The potential negative role of the β-casein variant A1 in human health has stimulated the planning of cattle breeding programs based on genetic selection to increase the frequency of the A2 variant, which is associated with increased milk digestibility. The aim of this work was to evaluate the frequencies of the different β-casein variants in Italian Holstein Friesian dairy cows from cattle farms located in central Italy to select a population of A2 homozygous animals. β-casein genotypes were identified by evaluating the presence of single nucleotide polymorphisms (SNPs) of the gene using PCR and sequencing analysis. The frequency of the desirable β-casein variant A2 in the studied bovine population was 0.61. The frequency of the undesirable A1 variant in the studied bovine population was 0.30. The frequency of the A2 allele was higher than expected for the breed; therefore, genetic selection for the A2 variant in these animals could be achieved in a fairly short time using A2 homozygous bulls.
牛奶中的大多数蛋白质是酪蛋白，它们分为四组（α-s1、α-s2、β和κ），分别由不同的基因（分别为 、 、 和 ）编码。在本研究中，我们关注β-酪蛋白等位基因变体A1和A2，因为它们对牛奶的技术特性和人类健康有影响。β-酪蛋白变体A1的消化会导致β-酪蛋白吗啡7（BCM-7）的形成，这是一种生物活性肽，有人认为它可能是各种人类疾病的一个原因，并且与牛奶消化率低有关。β-酪蛋白变体A1在人类健康方面的潜在负面作用促使人们计划开展基于基因选择的奶牛育种项目，以提高A2变体的频率，A2变体与牛奶消化率的提高有关。这项工作的目的是评估位于意大利中部奶牛场的意大利荷斯坦弗里生奶牛中不同β-酪蛋白变体的频率，以选择一群A2纯合动物。通过使用PCR和测序分析评估 基因的单核苷酸多态性（SNP）的存在来鉴定β-酪蛋白基因型。在所研究的牛群中，理想的β-酪蛋白变体A2的频率为0.61。在所研究的牛群中，不理想的A1变体的频率为0.30。A2等位基因的频率高于该品种的预期；因此，使用A2纯合公牛，可以在相当短的时间内实现对这些动物的A2变体进行基因选择。
