Association of β-casein gene polymorphism with milk composition traits of Egyptian Maghrebi camels (Camelus dromedarius).

Amira M Nowier,Sherif I Ramadan

doi:10.5194/aab-63-493-2020

Amira M Nowier, Sherif I Ramadan

Open Access

https://doi.org/10.5194/aab-63-493-2020

Copy DOI

Abstract

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 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.

Highlights

Camels are multipurpose animals used for meat and milk production, agricultural work and transportation, and for racing contests and tourism
Among the 68 tested Maghrebi camels, the A/G genotype showed the highest frequency of 50 %, while the A/A and G/G genotypes occurred at a frequency of 38 % and 12 %, respectively (Table 2)
This study aimed to identify CSN2 gene polymorphism in Egyptian Maghrebi camels and to determine their association with the chemical composition of milk

Summary

Introduction

Camels are multipurpose animals used for meat and milk production, agricultural work and transportation, and for racing contests and tourism. In Egypt, there are different dromedary camel breeds: Maghrebi, used for milk and meat production; Somali and Sudani for racing; and Falahy for agricultural work (Wardeh et al, 1991; Ramadan et al, 2018; Nowier et al, 2020). A growing demand for camel milk and processed milk products like pasteurized milk, flavored milk, fermented milk, milk tea, cheese, and butter has driven the commercialization of dairy camel farming Products of camel milk are a good source of energy and nutrients, and they improve the limited shelf life of camel milk (Brezovecki et al, 2015). Intensive dairy camel farms are being established in the Gulf countries, Tunisia, Australia, Europe, and the USA to supply the local and international markets (Hammadi et al, 2010; Ayadi et al, 2013; Nagy and Juhasz, 2016; Faye, 2018).

Objectives

Methods

Results

Conclusion