THE DAIRY COW

Hawke's Bay Tribune, Volume XX, Issue 281, 15 November 1930, Page 12

THE DAIRY COW

ITS MINERAL NEEDS. In “Bibby’s Hearth and Farm” there is an article upon mineral needs of dairy cows by Mr W. Biften. Of the live stock of the farm dairy cattle make the greatest call for minerals in their diet, he says. The minerals absorbed go to build up the bones, maintain the balance of salts in the blood, provide for the development and birth of calf, and supply the “ash” contained in the milk. Considering the high standard of milk production which a good proportion of our cows aro achieving, apart from other bodily need for minerals, there is certainly risk that rations may occasionally be short in one or two of those elements. The outcome of such an insufficiency is a weakening of the animal’s constitution, thus making it more susceptible to certain contagious diseases. Here there may bo noted, too, the recent discovery by Dryerre and Greig, of Edinburgh, that milk fever in cows is always associated with a deficiency of lime in the blood. To an extent there is a greater risk of a herd suffering from mineral short age than from lack of flesh-forming or energy-giving nutrients. This is because there is no way of measuring by inspection the extent to which the mineral stores of the body have been depleted, while loss of condition from Want of protein or carbohydrate soon makes itself evident. The fact that common salt (sodium chloride) is indispensable for the well-being of the dairy herd is well known. Sodium is required to maintain the supply in the blood, while chlorine furnishes an clement of the hydrochloric acid found in gastric juice, the digestive agent of the proteins consumed. lODINE. A number of other mineral elements are found in the animal body, but of these not more than three are at all likely to be deficient in the blood. One of them, iodine, is a special importance, not only as a safeguard against goitre, but because of the fact that the animal cannot fuiiy absorb the calcium, phosphorus and iron it requires except in conjunction with small quantities of iodine/ The proper functioning of the glands of the body which deal with nutrition, as well as those which have to do with reproduction, appears to depend on the presence of iodine in small quantity. Because of the importance of this element many stockowners take the precaution of adding a little finelypowdered potassium iodine to mixtures of minerals provided for the stock. So little as 2 oz. of iodide to 1 cwt. of salts mixtures will remove all likelihood of deficiency. The two minerals most likely to be short in the food of dairy cattle are calcium (lime) and phosphorus. Notwithstanding an abundance of other food materials, if the supply of these is withheld long enough the cow’s flow of milk will eventually drop. Deep-milking cows call for relatively large supplies of calcium and phosphorus. A gallon of cow’s milk contains, roughly, i oz. of lime and 1-3 oz of phosphoric acid. Therefore a cow giving 4 gallons of milk is subjected to a daily drain of 1 oz. of the former and 1 1-3 oz. of the latter. To ensure that this loss may ho made good it is not enough to feed a ration providing simply the amounts of calcium and phosphorus contained in the milk yield, for a cow is able to absorb into her system oly a proportion—-a varying one—of the mineral elements she ingests. For this reason much more should be available in the diet than will be required for the manufacture of the milk.