1. Lactoferrin was identified in milk from a variety of mammals (guinea-pig, cow, goat, pig, mare and mouse) on the basis of its electrophoretic mobility, the stability at acid pH of its iron-complex an dits immunological properties. 2. Milk from rats, rabbits and dogs was apparently devoid of lactoferrin. 3. A comparison of the concentration of lactoferrin wiht that of iron (the latter based on data from the literature), in milk from various mammals, failed to provide any grounds for the assumption of a direct role of lactoferrin in the excretion of iron into milk.

Lactoferrin in milk from different species

Copper and zinc are readily determined in biological material by atomic absorption spectrophotometry. Two procedures are presented for the quantitative estimation of these metals in serum. One of these involves simple dilution and aspiration into the burner of the instrument. Suitably prepared standards must be used. The other method involves trichloroacetic acid preparation of the proteins prior to aspiration. With both methods satisfactory results in precision and recovery of added metals are obtained. Urinary copper determinations require chelation of the metal with ammonium pyrrolidino dithiocarbamate or some similar sequestering agent and concentration by extraction of the chelate into a suitable organic solvent. A similar procedure must be used in analyzing cow's milk for copper. Tissue analysis requires heating with boiling nitric acid and removal of the acid under reduced pressure prior to aspiration into the burner. It has been shown that procedural errors in such determinations are very much smaller than biological variation.

Determination of Copper and Zinc in Biological Material

Off Flavors of Milk: Nomenclature, Standards, and Bibliography

INTRODUCTION . METHODOLOGY IN ANALYSIS OF MILK . Sample Collection . Methods of Estimating Milk Output . Analytical Techniques . DEVELOPMENTAL CHANGES IN TRACE ELEMENT CONCENTRATIONS DURING LACTATION . Patterns of Trace Element Concentrations During Lactation . Iron . Copper . Zinc •.•...• ••.•.• •.•........•...••.• ••• ••• •..•....... Manganese . DIETARY INFLUENCE ON MILK COMPOSITION-EFFECTS OF MATERNAL TRACE ELEMENT DEFICIENCY OR EXCESS ......... . Iran . Copper . Zinc . Manganese . Comments . TRACE ELEMENT BINDING FACTORS IN MILK . Iran . Zinc . Copper . Manganese . Comments . BIOA V AILABILITY OF TRACE ELEMENTS IN MILK .. Iran . Zinc . Copper and Manganese . INFANT FORMULAS .. CONCLUDING REMARKS .

Iron, copper, zinc, and manganese in milk.

The concentration of iron in cow's milk, 0.40-0.59 microgram/ml, was found to be very similar to that of human milk, 0.20-0.69 microgram/ml. The copper concentration of cow's milk (0.06-0.09 microgram/ml) is lower than in human milk (0.24-0.50 microgram/ml) whereas the concentration of zinc is higher in cow's milk (3.23-5.15 micrograms/ml) than in human milk (1.16-3.83 micrograms/ml). Cow's milk contains about 4-5 times more calcium and magnesium, 854-1430 micrograms/ml and 87-131 micrograms/ml, respectively, than human milk (220-252 micrograms/ml and 26-35 micrograms/ml). Cow's milk was fractionated and the trace element and mineral contents of the different fractions were compared to results from human milk. The casein fraction in cow's milk contains a large proportion of the total amounts of the elements cited above (Fe 24%, Cu 44%, Zn 84%, Ca 41%, Mg 25%) whereas human casein only binds minor amounts (Fe 9%, Cu 7%, Zn 8%, Ca 6%, Mg 6%). Whey proteins bind a major part of these elements in human milk, but not in cow's milk. Significant amounts of iron are bound to the lipid fraction in both cow's and human milk (14 and 33%, respectively), predominantly bound to the outer fat globule membrane. Low molecular weight compounds (ligands) bind significant proportions of all the elements investigated in both cow's and human milk, with the exception of zinc in cow's milk, of which only 2% is associated with this fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

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R.L. King

Papers

Relation of Natural Copper in Milk to Incidence of Spontaneous Oxidized Flavor

Distribution of Natural and Added Copper and Iron in Milk

Adsorption of Copper on Stainless Steel