The relation of fodder to the antiscorbutic potency and salt content of milk

With 15 Figures)THE discovery by Pyne(i) that the colloidal phosphate of milk is largely, if not entirely, tricalcium phosphate was a valuable link in the chain of evidence required for the complete elucidation of the mineral equilibria of milk. A method for estimating tricalcium phosphate in milk was examined by the writer (2) in a previous paper, and the suggestion was made that it should prove an effective means of exploring the hitherto obscure partition of calcium and phosphorus. The present paper gives the results of work undertaken with this end in view.Fifty-four samples of mixed milk (alternatively a.m. and p.m.), from the College herd of thirty-six to forty-eight Dairy Shorthorns, were taken at regular intervals during the period October 1935 to November 1936. All samples were kept in cold storage at 45° F. until required in the laboratory. METHODS OF ANALYSISOn arrival in the laboratory, the samples were placed in a water-bath at 30° C. and then cooled to room temperature. Quantities required for the various determinations were measured with a pipette, and the weight of milk or whey so discharged was subsequently ascertained. All estimations were made in duplicate. Soluble constituentsFor this purpose the analyses were conducted on the rennet whey, correcting for the removal of fat and protein by the use of the factor 100-(F + P-0-4) 100where F = percentage fat, and P = percentage nitrogen x 6-38. This factor has been found suitable for converting whey percentages to soluble milk constituents (2). The whey was prepared by adding 225 ml. of milk at 30° C. to 1-5 ml. of rennet extract, maintaining at 30° C. in a water-bath, cutting with a stainless steel knife when of the requisite firmness, and then filtering through a battery of four Whatman No. 40 11 cm. filter papers. The time of coagulation was

Section: Seasonal Variationcontrasting

confidence: 82%

156. The composition of milk and whey, with special reference to the partition of calcium and phosphorus

Ling

1937

“…The nutritive value would therefore appear to be higher in the summer months than at other times of the year, but whether this factor would be responsible for an increase in the calcium and phosphorus content of the milk as found by Davies and Provan is at present a matter for speculation. Hess, Unger and Supplee (55) reported similar results for the beneficial effect of pasture feeding on the calcium and phosphorus content of milk, though in this case the fact that previous to grazing the cows had been fed on a diet devoid of antiscorbutic vitamin adds another factor to those to be considered. Five Holstein cows, freshened about 2 months previously, were used for this experiment and they were fed throughout the winter on a normal ration consisting of ensilage, hay, and concentrates.…”

Section: / the Range Of Variation Of The Mineral Constituentsmentioning

confidence: 60%

“…Hess, Unger and Supplee (55) claimed that a change from winter to summer feeding increases the citric acid content of the milk. Their results are shown in Table XXXVI, and as previously explained the analyses are for composite samples of five cows over a whole day's milking.…”

Section: Occurrence Of Citric Acid In Milkmentioning

confidence: 99%

25. The Mineral Constituents and Citric Acid Content of Milk

Allen

1931

“…The data on which the opinions are based, however, are rather meagre and, on the whole, inconclusive. Hess, Unger and Supplee (34) found that the calcium and phosphorus content of the milk was higher when cows were on pasture. But as pointed out by Maynard(35) this result is based upon only one analysis of a pooled sample of milk from a group of cows before and after grazing.…”

Section: R6le Of Minerals In Nutritionmentioning

confidence: 95%

12. The Mineral Requirements of Dairy Cattle

Crichton¹

1930

The most important fact brought out by a review of the present position of our knowledge of mineral metabolism and the mineral requirements in the dairy cow is, that, in spite of the amount of work which has been done on the subject, our information is exceedingly scanty. We know that deficiency of calcium or phosphorus may affect rate of growth, milk yield, breeding capacity, and in all probability susceptibility to certain diseases. We know also that even on what are counted good rations, depletion of the tissues, especially of calcium, in heavy milking cows during lactation is common. In some districts deficiency of iodine causes pathological conditions, and it is common knowledge based on practical observations that even on pasture there is liable to be a deficiency of chlorine. With regard to the possibility of deficiencies of other mineral elements and the effect of such deficiencies on the health and milk production of cows, we have not yet even begun to accumulate knowledge. It is thus impossible to make a final pronouncement with regard to any of the main problems. We need many more data on the metabolism of minerals in the lactating animal and on feeding experiments of long duration with rations of different mineral content. Such information as we have, however, suggests that the subject is one of great potential practical importance, and that if the necessary information were available it might be applied to the more economical production of milk, both by increasing milk yield and by reducing mortality from disease.With regard to the information we do possess, much of it is not immediately applicable in practice because the data have been accumulated with diets and under conditions which have no parallel in practice. The following conclusions sum up in a general way the practical bearing of our present knowledge.