FEEDING DAIRY COWS

New Zealand Herald, Volume LXXIII, Issue 22402, 24 April 1936, Page 8

FEEDING DAIRY COWS

FACTORS IN NUTRITION BY HYGEIA There is a greater risk of a dairy herd suffering from mineral shortage than from lack of flesh - forming materials or energy-giving nutrients. This is because there is no way of measuring, by inspection, the extent to which tho 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 is indispensible to the dairy herd is well known. Sodium chloride is required to maintain the supply in the blood, while chlorine furnishes an element of the hydrochloric acid found in gastric juice, the digestive agent of tha proteins consumed. If feeding stuff is burnt, there is always ash loft. This is the mineral matter which the plant drew from the earth while it was growing. The amount of mineral varies with the plant species, but is not always constant in any one variety or ago of plant, being often, also, influenced by tho soil and climate. A rich soil or an application of fertiliser usually increases the mineral matter in a plant. It is now known that the mineral contents of their food is most important to dairy cattle, and if they are not receiving foods which are rich in certain minerals, these must be supplied in some other form. Most plants contain potassium, calcium, magnesium and iron, and some contain small quantities of sulphur and phosphorus. Tho three minerals that the cow requires daily are salt, lime and phosphorus. There are other minerals required, but they are usually found in sufficient quantity in her daily rations. There is a deal to bo said about the assimilation of minerals by dairy cows. It is now known that liigh-producing cows, fed the usual ration of hay, silage and green feed, may take lime and phosphorus out of their bones to put in the milk early in the lactation period, and that they will do this though the minerals are supplied to them in their food. When this discovery was made, many men began to question the usefulness of feeding minerals to dairy cows. Later work has shown that if there was a sufficient supply in the ration the losses of lime and phosphorus were restored toward the end of tho lactation, or during tho dry period. Thus it became known that the bones contain calcium and phosphorus as a deposited reserve to be used when needed. If tho drain on the skeleton is not too heavy and is restored by calving time, no barm is done. This discovery indicated that for the adequate nutrition of the dairy cow, the dry period was just as imporant as, if not more so, than the period j of heaviest production. |