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Biomedical subjects

D D Muir

Publications and source records attributed to D D Muir.

9 recordsLinked to original sources
PubMed2001

Thrice-daily milking throughout lactation maintains epithelial integrity and thereby improves milk protein quality.

Cows managed for extended lactations of 16 months duration were milked on a half-udder basis twice or thrice daily, commencing in lactation week 9. Mammary epithelial integrity (assessed by milk sodium : potassium ratio) was greater in the half-udder which was milked thrice daily. This difference was evident throughout the lactation but became greater after week 41. Milk protein composition was assessed during late lactation (52+/-3 weeks). Casein number (casein as a proportion of total protein) was significantly higher in half-udders milked thrice daily, as were the relative amounts of alpha- and beta-caseins, whilst those of kappa- and- caseins were reduced. Two days of inverted milking frequency (i.e. thrice-milked udder halves now milked twice, and vice versa) only partly reversed these differences. We concluded that thrice-daily milking will help to prevent or ameliorate the usual decline in milk processing quality associated with late lactation. Part of this effect is due simply to reduced exposure to proteolytic enzymes as a result of decreased storage time in the udder, but part is due to a better maintenance of epithelial tight junction integrity as lactation advances, which restricts leakage of proteolytic enzymes from serum into milk.

Animals↗
PubMed1979

Inorganic constituents of milk: I. Correlation of soluble calcium with citrate in bovine milk.

A high correlation was found between soluble calcium and citrate concentrations during a study of seasonal changes in the composition of the commercial milk supply to South-west Scotland. A simple physicochemical model of the ion equilibria in the aqueous phase of milk suggests that the observed correlation is causal. This hypothesis was corroborated by an analysis of data on individual cow milks and by experiments involving the addition of citrate to milk at constant pH.

Animals↗
PubMed1973

The structure of hydroxyethyl starch.

1. It is suggested that the structure currently used to describe hydroxyethyl starch (a blood plasma volume expander) is a gross oversimplification.2. A model having a much more complex substitution-pattern is proposed, and an accurate, rapid test has been devised for distinguishing between the two models.3. This test shows that the simple model has no basis in reality, and that the more complex substitution pattern is correct.4. Studies involving the enzymic hydrolysis of hydroxyethyl starch are shown to provide qualitative support for the new model, and the significance of the findings is discussed.

Chemical Phenomena↗