A study of polymorphism in milk proteins from local and imported dairy sheep in Australia by capillary electrophoresis

Patrick Clement, Samson Agboola, Roberta Bencini

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

Casein and whey protein fractions of milk obtained from 47 ewes of five breeds or crossbreeds (Awassi, Merino, East Friesian×Merino, Awassi×Merino and Awassi×East Friesian) were analysed by capillary electrophoresis (CE). The experiments were performed on a Beckman P/ACE' system 5510 with an uncoated fused-silica capillary and a low pH buffer containing urea and a polymeric additive. The four major caseins ('s1-, 's2-, ß- and '-casein) in an acid precipitate were well separated, as were the two whey proteins, '-lactalbumin ('-La) and ß-lactoglobulin (ß-Lg). The electromigration of the proteins was in the order of '-La, ß-Lg, 's2-CN, 's1-CN, '-CN and ß-CN. The milk samples were composed of the same variant of '-La and two different genotypes (A and B) of ß-Lg while the ß-Lg AB genotype was evident in the milk of some animals. The 's1-CN fractions displayed considerable heterogeneity with at least 4 different peaks, representing 4 different variants. A fifth peak, corresponding to the Welsh variant (or 's1-CN D), was present in 90% of the ewes' milk samples. The '-CN fraction was resolved as a single peak, while the ß-CN revealed significant heterogeneity with 3 variants. It appears that the presence of the 's1-CN Welsh variant in Merino ewe and its crosses with Awassi and East Friesian ewes adversely affected milk composition and yield.
Original languageEnglish
Pages (from-to)63-69
Number of pages7
JournalLWT - Food Science and Technology
Volume39
Issue number1
DOIs
Publication statusPublished - 2006

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