Nowier Amira M, Ramadan Sherif I
Biotechnology Research Department, Animal Production Research Institute, Agriculture Research Center, Dokki, Egypt.
Animal Wealth Development Department, Faculty of Veterinary Medicine, Benha University, Toukh, Egypt.
Arch Anim Breed. 2020 Dec 22;63(2):493-500. doi: 10.5194/aab-63-493-2020. eCollection 2020.
The objectives of this study were to detect the polymorphism of 2126 SNP in the -casein (CSN2) gene among Egyptian Maghrebi camels and to investigate the association of 2126 SNP genotypes, parity, lactation stage, and temperature-humidity index (THI) with the milk composition traits of Maghrebi camels. Sixty-eight hair samples were collected from three different populations of Maghrebi camels for DNA extraction. Fat, protein, total solids, solids-not-fat, and lactose percentages were determined in Maghrebi camel milk using an automatic milk analyzer device. Three different genotypes - A/A, A/G, and G/G - were identified in the 5 flanking region of -casein gene by using PCR-RFLP method with the A/G genotype showing the highest frequency. Association among these three genotypes with milk composition traits suggests a positive effect of A/A genotype on acidity and protein percentage. Higher protein and acidity values were observed in the milk of individuals carrying the A/A genotype. The protein percentage of this study significantly increased from the first till the fourth parity and then decreased. Fat and total solid percentages were significantly higher in the late stage of lactation, while lactose showed a decreasing trend from the early till the late stages of lactation. Fat and protein percentages were highest in the low THI class. Our results encourage the utilization of Maghrebi camel milk for cheese and butter processing at the late lactation stages of the middle parities of their productive life. Moreover, the A/G SNP of the gene may be used as a DNA marker in selection programs for the improvement of camel milk composition. Further studies are needed in order to fully explore the variation in the chemical composition of camel milk due to the effect of CSN2 gene, parity, lactation stage, and THI factors.
本研究的目的是检测埃及马格里布骆驼β-酪蛋白（CSN2）基因中2126 SNP的多态性，并研究2126 SNP基因型、胎次、泌乳阶段和温湿度指数（THI）与马格里布骆驼乳成分性状之间的关联。从三个不同的马格里布骆驼种群中采集了68份毛发样本用于DNA提取。使用自动乳分析仪测定马格里布骆驼乳中的脂肪、蛋白质、总固体、非脂固体和乳糖百分比。通过PCR-RFLP方法在β-酪蛋白基因的5侧翼区域鉴定出三种不同的基因型——A/A、A/G和G/G，其中A/G基因型的频率最高。这三种基因型与乳成分性状之间的关联表明，A/A基因型对酸度和蛋白质百分比有积极影响。携带A/A基因型的个体的乳汁中观察到较高的蛋白质和酸度值。本研究中蛋白质百分比从第一胎到第四胎显著增加，然后下降。脂肪和总固体百分比在泌乳后期显著较高，而乳糖从泌乳早期到后期呈下降趋势。脂肪和蛋白质百分比在低THI类别中最高。我们的结果鼓励在马格里布骆驼生产期的中期泌乳后期利用其乳汁进行奶酪和黄油加工。此外，该基因的A/G SNP可作为改善骆驼乳成分的选择计划中的DNA标记。为了充分探索由于CSN2基因、胎次、泌乳阶段和THI因素的影响导致的骆驼乳化学成分的变化，还需要进一步的研究。
