QUALITY OF MILK.

Otago Witness, Issue 3404, 11 June 1919, Page 10

QUALITY OF MILK.

The onus of proof that milk from the original producer—the cow, has not been tampered with rests upon the vendor—a fact -which necessarily at times may prove an anxious ordeal to an honest vendor of milk. Milk may fall below the official regulations in respect to the percentage of butter-fat and "solids than fat." To enable reliable information in this connection, investigations have been made at Armstrong College, Newcastle-on-Tyne, and a Teport on the results, published in the Journal of the Central Chamber of Agriculture. It would seem that discretion by the local authorities may well be displayed in certain circumstances.

From February, 1904 to 1915, the mixed milk of five cows, milked three times a day, was tested on 2716 days. On 783 of these days the mixed morning milk contained less than 3 per cent, fat; the noon milk was deficient on only five days and the evening milk on eight days. During the same period on 252 days the mixed milk of five cows, milked twice a day, was found to be deficient in fat 20 times in the morning and nine times in the evening. It is thus clear that_ two milkings a dav at as nearly equal intervals as possible considerably reduced the number of times when the milk was liable to be deficient, but did not remove the risk. It is a safeguard, therefore, to milk but twice a day, and the iisual thing with us, although at home it may at times suit the producer to milk three times in the day. In respect to "solids not fat," the investigation showed similar discrepancies. These milkings involved greater risks of deficiency than two milkings ; but still, here again the risk was not eliminated. The matter of feeding some concentrated food was considered while the cows were on pasture during the summer, with the idea of ascertaining whether it was profitable. Trials were made for three years with two lots of five cows. In the first year Lot I—of five cows—received 41b of cotton cake, and 41b of maize meal per cow; and Lot .2 got half those quantities. Each cow in Lot 1 gave 20.6 pints daily, and each cow in Lot 2 gave 21 pints. In each case the average percentage of "fat" and "solids not fat" were above the regulation limit. In the second year each cow in Lot 1 received 21b cake and 21b maize meal for the first five weeks, and double these quantities for the second five Aveeks, both in addition to grass. The cows in Lot 2 got grass only. Result, each cow in Lot 1 gave 25 pints daily, and each COWS in Lot 2 24 pints. Similar trials with similar results Avere made the following year. It should be noted that in the trials during the two summers 1905 and 1915 the cows receiving cake and meal gave morning milk deficient in fat on 27 out of a total of 154 days, while those receiving no cake and meal were so deficient only on 16 days. In these trials it was noted that Avhen coavs are turned out to grass in early summer the Aoav of milk is increased for a time, whether cake and meal are fed or not. The results sboAV that neither the quantity of milk given nor the content of the milk in fat or "solids not fat" were increased Avhen cake and meal were fed in addition to pasture. The pasture was only of average quality. The only effect of the cake and meal Avas that the cows Avere kept in in somewhat better condition, but this nothing like compensated for the cost of these foods. "These results slioav that cows in milk, grazing on fair average or better pastures, will give no return for cake and meal fed in addition, this being a most important point at the present time."

Further trials were made in respect to moderate versus heavy rations of concentrated food, Four trials were made — A, B, C, D. In experiment A each cow received 601 b sAvedes, 151 b hay, and 61b straAV chaff Avith concentrated food in the proportion of three parts cotton cake, three parts maize meal, and three parts malt dust. In experiment B the concentrated foods Avere fed in the same proportion Avhile the cows were on pasture. In experiments C and D each coav received 501 b swedes, 121 b hay, and 61b chopped straw, while the concentrated foods were in the proportion of two parts maize meal, one part linseed, and one part cotton cake. The results showed that, on the average, the quantities of milk wore only increased slightly Avhen the large amounts of concentrated foods Avere fed. and that the percentages of fat or of "solids not fat" in the milk were not at all increased thereby. While they show clearly that cows that are moderate milkers, and are receiving fair rations of food, Avill not give more or better milk if the concentrated food is increased, it must not be forgotten that a coav, naturally a heavy milker, requires additional food corresponding to her milk yield, so far as it is safe to feed up to this extent. It is- therefore of the greatest importance in feeding a herd of milking coavs that the better milkers should receive heavier rations of the concentrated foods.