Details are given of a histochemical technique suitable for the identification of lipoproteins in cheese based on their property of forming insoluble complexes with sulphated polysaccharides.

The vitamin content of ultra-high-temperature (UHT) processed milk was compared with that of the original raw milk. Three processes were used. In the first, which caused no change in oxygen content, the milk was heated and cooled in a plate-type heat exchanger. In the second, the milk was again heated indirectly and then evaporatively cooled, leaving in the milk about one-third of the initial oxygen content. In the third process the milk was heated by direct steam injection and cooled by evaporation and contained little or no residual oxygen.

On processing and during subsequent storage for 90 days there was no loss of vitamin A, carotene, vitamin E, thiamine, riboflavine, pantothenic acid, biotin or nicotinic acid. There was little or no loss of vitamin B6 or vitamin B12 on processing, but up to 50% of each of these vitamins was lost during 90 days' storage. All the dehydroascorbic acid (DHA) and about 20% of the ascorbic acid (AA) was lost on processing. There was no further loss of AA during 90 days’ storage when no residual oxygen was present, but in milks containing more than about 1 ppm oxygen all the AA was lost within 14 days. About 20% of the folic acid was lost on processing; thereafter, as with ascorbic acid, the extent of the loss on storage depended on the residual oxygen content of the milk: in the absence of oxygen the folic acid was stable.

The fact that rumen micro-organisms have a modifying effect on the utilization of food nitrogen by ruminants has been recognized for very many years (references to early work are given in Hungate, 1966) but until about 1947, when this subject was reviewed by McNaught & Smith (1947), many of the processes involved were not well understood. Since that time a large amount of work has been done in this field and more recent reviews (Chalmers & Synge, 1954; Blackburn, 1965; Hungate, 1966; Waldo, 1968) present a much clearer picture. Most of the work covered by these authors will be mentioned only briefly in the present review and attention will be directed mainly to developments reported in the last few years. Few references to work published before about 1964 will be given as they may readily be found in later publications.

A study was made of the changes in the pathways of glucose catabolism in slices of lactating rat mammary gland which occurred when acetate or pyruvate was added to the medium.

When acetate was added there was an increase in the rates of oxidation of the C(2) and C(6) atoms of glucose but little change in that of the C(1) atom. The amounts of these carbon atoms which were incorporated into fatty acids, lactic acid and glyceride glycerol were reduced, but the results showed that the relative proportion of the glucose converted to these substances which passed through the pentose phosphate pathway was increased.

When pyruvate was added, the rates of oxidation of the C(1), C(2) and C(6) atoms were all reduced to about the same extent. The incorporation of the glucose carbon into fatty acids was almost abolished and its incorporation into lactic acid and glyceride glycerol was very much reduced. The results showed that most of the glucose incorporated into these compounds under these conditions passed through the pentose phosphate pathway.

Evidence is presented which suggests that the triose phosphates are not in complete isotopic equilibrium in lactating rat mammary tissue.

These results are discussed in relation to the existence of 2 pools of acetyl coenzyme A, one intra- and the other extra-mitochondrial, and to the possible inhibition of certain steps of the glycolytic pathway.

As previously described, the process consists essentially of the passage of milk at pH 5·2–5·3 through an ion exchange resin charged with a suitable mixture of the ions of Ca, K, Na and Mg.

The nutritive quality of plant-treated milk was assessed in feeding experiments with weanling rats and 1- to 2-day-old piglets.

No deleterious effect was found with rats, but tests with piglets indicated that the nutritive quality of the milk was impaired as evidenced by a higher mortality.

Post mortem examinations revealed no specific cause of death.

The use of hydrochloric acid instead of citric acid resulted in a lower mortality, though not as low as that found in piglets receiving untreated milk.

The difference in mortality between animals receiving treated and untreated milk was not consistent and was not found in some experiments.

It is concluded that the milk is unsuitable for piglets and that its suitability for human infants remains in question.

Total carotenoids, β-carotene and α-tocopherol concentrations were determined in serum from healthy dairy cattle of various ages, grazing good quality pasture, in different areas of New South Wales. The relationships of these components with each other and with age of the animal were examined.

Mean serum β-carotene concentrations for heifers and cows were 0·68 and 1·20mg/100ml, respectively. These concentrations were somewhat higher than those found for calves (0·20mg/100ml) and weaners (0·37 mg/100 ml). Total corresponding carotenoid values were generally about 20% higher than those for β-carotene for herds.

Mean serum α-tocopherol concentrations for heifers and cows were 0·54 and 0·90 mg/100ml, respectively. Again, these values were higher than those found for calves (0·22 mg/100 ml) and weaners (0·37 mg/100 ml).

There was a close relationship between serum α-tocopherol and β-carotene (r=0·90), between serum α-tocopherol and total carotenoids (r=0·92), and between serum β-carotene and total carotenoids (r= 0·99).

A study was made of the changes in the rates of oxidation of the C(1), C(2) and C(6) atoms of glucose and in the pathways of glucose catabolism in sheep udder tissue in vitro which occurred when acetate and pyruvate were added.

Whereas in rat mammary tissue the rate of oxidation of the C(1) atom of glucose was very much greater than that of the C(6) atom, the ratio of the rates of oxidation of these 2 atoms in sheep tissue was less than 2 when glucose was the only substrate.

The addition of acetate resulted in an unequal stimulation of the oxidation of these 2 atoms, with the result that the ratio of their rates of oxidation was about doubled. The rate of oxidation of the C(2) atom was also increased.

Acetate also increased the participation of the pentose phosphate pathway in glucose catabolism as measured by the incorporation of the C(1) and C(6) atoms of glucose into fatty acids, lactic acid and glycerol.

Pyruvate produced little effect on the rate of oxidation of the C(1) atom but somewhat depressed that of the C(6) atom of glucose. At the same time, it caused a large increase in the participation of the pentose phosphate pathway.

These results are discussed with reference to re-cycling of glucose carbon in the pentose phosphate pathway and to the relationship between that pathway and fatty acid synthesis. It is noted that the incorporation of glucose carbon into the 3 intermediates used gave values for the participation of that pathway which were in better agreement than was obtained in rat tissue. It is concluded that triose phosphates are more nearly in equilibrium in sheep than in rat mammary tissue.