Chao C H, Shiau J W
Northern Region Branch, Taiwan Livestock Research Institute, Ministry of Agriculture, 207-5, Bi-tou-mian, Wu-hoo village, Si-hoo Township, Miaoli County, Taiwan.
Pol J Vet Sci. 2025 Jun;28(2):303-309. doi: 10.24425/pjvs.2025.154951.
β-Casein accounts for approximately 30% of total milk protein, with the A1 and A2 variants being the most common. A1 β-casein may release β-casomorphin-7 (BCM-7) during digestion, which is associated with adverse health effects, whereas A2 β-casein does not. This study investigated the A2 allele frequency and its potential influence on milk performance in Holstein cattle in Taiwan. A total of 1,050 cows from five herds were genotyped using the GeneSeek 50K SNP chip. The A2 allele frequency ranged from 0.58 to 0.75 among herds, with an average of 0.66. Hardy-Weinberg equilibrium tests indicated no significant deviation within herds. Pedigree validation confirmed Mendelian inheritance of A1 and A2 alleles. Furthermore, 348 cows with complete lactation records were evaluated for 305-day mature equivalent milk and fat yields across genotypes. Although cows with the A1/A1 genotype showed numerically higher milk and fat yields, one-way ANOVA and Tukey's HSD tests revealed no statistically significant differences. These results suggest that while A2 allele selection is increasing in Taiwan, β-casein genotype does not significantly influence milk or fat production in the studied population.
β-酪蛋白约占牛奶总蛋白的30%，其中A1和A2变体最为常见。A1 β-酪蛋白在消化过程中可能释放β-酪蛋白吗啡-7（BCM-7），这与不良健康影响有关，而A2 β-酪蛋白则不会。本研究调查了台湾荷斯坦奶牛的A2等位基因频率及其对产奶性能的潜在影响。使用GeneSeek 50K SNP芯片对来自五个牛群的总共1050头奶牛进行了基因分型。各牛群中A2等位基因频率在0.58至0.75之间，平均为0.66。哈迪-温伯格平衡检验表明各牛群内无显著偏差。系谱验证证实了A1和A2等位基因的孟德尔遗传。此外，对348头有完整泌乳记录的奶牛按基因型评估了305天成熟当量的产奶量和产脂量。虽然A1/A1基因型的奶牛在产奶量和产脂量上数值较高，但单因素方差分析和Tukey's HSD检验显示无统计学显著差异。这些结果表明，虽然台湾对A2等位基因的选择在增加，但β-酪蛋白基因型对所研究群体的产奶量或产脂量没有显著影响。
