Department of Genetics, Faculty of Veterinary Medicine, Bursa Uludag University, Bursa, Turkey.
Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Bursa Uludag University, Bursa, Turkey.
Anim Biotechnol. 2023 Dec;34(8):4116-4125. doi: 10.1080/10495398.2023.2267614. Epub 2024 Jan 30.
The A2 milk marker is gaining popularity worldwide; thus, many farms plan to convert their dairy cattle herds to the A2A2 genotype. Variation in beta-casein genotypes needs to be monitored in large dairy cattle populations. Therefore we aimed to evaluate the genotypic distributions, population genetics, and diversity parameters in Holstein-Friesian cows. A total of 1200 cattle were genotyped using the Affymetrix Axiom array system. We performed an association analysis regarding the genotypes and phenotypic traits, including lactation and test-day milk yield. We next evaluated the effects of the genotypes considering the genetic merit of the animals. Animals were grouped based on their PTAs for milk production, fat, protein, and daughter pregnancy rate. Thus, we tested the genotype × genetic merit interaction for significance. The A2 allele frequency is remarkably high (0.68), and the heterozygous genotype is predominant (46.25%). The marker showed intermediate variability and diversity levels, indicating a considerable frequency of the A1A1 genotype (9.33%) remains in the population. ANOVA results showed no significant association between the genotypes and milk yield traits. A similar finding is valid for the genotype × genetic merit regarding the genomic test results. The data presented here may be helpful for further investigations and applications on A2 milk production.
A2 牛奶标记物在全球范围内越来越受欢迎；因此，许多农场计划将其奶牛群转换为 A2A2 基因型。需要在大型奶牛群体中监测β-酪蛋白基因型的变异。因此，我们旨在评估荷斯坦奶牛的基因型分布、群体遗传学和多样性参数。使用 Affymetrix Axiom 阵列系统对 1200 头牛进行了基因分型。我们针对基因型和表型性状（包括泌乳和测试日牛奶产量）进行了关联分析。接下来，我们考虑动物的遗传优势来评估基因型的影响。根据产奶量、脂肪、蛋白质和女儿怀孕率的 PTAs 对动物进行分组。因此，我们测试了基因型与遗传优势的互作是否显著。A2 等位基因频率非常高（0.68），杂合基因型占主导地位（46.25%）。该标记显示出中等水平的变异性和多样性，表明在该群体中 A1A1 基因型的频率相当高（9.33%）。方差分析结果表明，基因型与牛奶产量性状之间没有显著关联。关于基因组测试结果，基因型与遗传优势之间的关联也同样有效。这里呈现的数据可能有助于进一步研究和应用 A2 牛奶生产。
