The objectives of this study were to detect the polymorphism of 2126A=G SNP in the β-casein (CSN2)
gene among Egyptian Maghrebi camels and to investigate the association of 2126A=G 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
50 flanking region of β-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 CSN2 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. |
