Demirel Ahmet Fatih, Çak Bahattin
Department of Animal Husbandry, Faculty of Veterinary Medicine, Van Yüzüncü Yıl University, Van, Türkiye.
Vet Med Sci. 2025 May;11(3):e70334. doi: 10.1002/vms3.70334.
Caseins are the major proteins found in cow's milk. There are four known casein fractions: α-casein, α-casein, β-casein and κ-casein, encoded by the CSN1S1, CSN1S2, CSN2 and CSN3 genes located on the sixth chromosome of cattle. These genes are considered candidate genes in marker-assisted selection. Therefore, it is essential to determine the relationship between these genes and quantitative characters.
This study aimed to identify genotypes of CSN1S1, CSN1S2, CSN2 and CSN3 genes and investigate their effect on milk components with the PCR-RFLP method in Holstein cattle.
The material of the study consisted of 519 Holstein cows that managed under intensive systems in Konya (n:189), Manisa (n:195) and Diyarbakır (n:135) provinces in Türkiye. Blood and milk samples from these cows were used in the study. The genetic structures of bovine CSN1S1, CSN1S2, CSN2 and CSN3 genes were examined by PCR-RFLP in three Holstein cattle populations. A general linear model (GLM) was applied to analyse the effect of genotypic variants on phenotypic characters.
Results indicated that milk solids-non-fat (SNF) (p < 0.01), protein (p < 0.05) and lactose (p < 0.01) percentages were significantly affected by the genetic variants of the CSN2 gene of cow in general population. CSN2 A2A2 genotype led to a significant increase in SNF, protein and lactose percentages by 0.14, 0.05 and 0.08 in comparison to other genotypes, respectively. Moreover, significant effect of the CSN1S1 BC (p < 0.05) and CSN3 AA (p < 0.01) genotypes on fat percentage were found in Konya province. Furthermore, a statistically significant genotype-by-environment interaction was identified in both the CSN1S1 (p < 0.05) and CSN3 (p < 0.01) genes in relation to milk fat content.
As a result, after increasing the number of studies that investigated the relationship between casein genes and milk traits and determined the genetic variation of CSN1S1, CSN2 and CSN3 genes of the Holstein cattle, these genes can be a strong genetic marker as marker-assisted selection programme in early selection.
酪蛋白是牛奶中的主要蛋白质。已知有四种酪蛋白组分：αs1 - 酪蛋白、αs2 - 酪蛋白、β - 酪蛋白和κ - 酪蛋白，由位于牛第六条染色体上的CSN1S1、CSN1S2、CSN2和CSN3基因编码。这些基因被认为是标记辅助选择中的候选基因。因此，确定这些基因与数量性状之间的关系至关重要。
本研究旨在利用聚合酶链反应 - 限制性片段长度多态性（PCR - RFLP）方法鉴定荷斯坦奶牛CSN1S1、CSN1S2、CSN2和CSN3基因的基因型，并研究其对牛奶成分的影响。
研究材料包括在土耳其科尼亚（n = 189）、马尼萨（n = 195）和迪亚巴克尔（n = 135）省集约化饲养系统下管理的519头荷斯坦奶牛。研究使用了这些奶牛的血液和牛奶样本。通过PCR - RFLP对三个荷斯坦牛群体的牛CSN1S1、CSN1S2、CSN2和CSN3基因的遗传结构进行了检测。应用一般线性模型（GLM）分析基因型变异对表型性状的影响。
结果表明，在总体群体中，奶牛CSN2基因的遗传变异对非脂乳固体（SNF）（p < 0.01）、蛋白质（p < 0.05）和乳糖（p < 0.01）百分比有显著影响。与其他基因型相比，CSN2 A2A2基因型导致SNF、蛋白质和乳糖百分比分别显著增加0.14、0.05和0.08。此外，在科尼亚省发现CSN1S1 BC（p < 0.05）和CSN3 AA（p < 0.01）基因型对脂肪百分比有显著影响。此外，在CSN1S1（p < 0.05）和CSN3（p < 0.01）基因中均发现了与乳脂肪含量相关的基因型与环境的显著交互作用。
因此，在增加了研究酪蛋白基因与牛奶性状之间关系并确定荷斯坦奶牛CSN1S1、CSN2和CSN3基因遗传变异的研究数量之后，这些基因可作为早期选择中标记辅助选择计划的强大遗传标记。
