Nutrition

The diet of dairy cows has to be mineral balanced due to the fact that through milk are eliminated significant amounts of minerals, especially calcium and phosphorus, but also potassium, sodium, chloride, etc. Moreover, the mineral substances have a plastic role in the organism, participating in a high proportion in the tissues supporting structure, as well as with a functional role by keeping the main body functions.

As a consequence, it is imposed the mineral balance of the dairy cows nutrition, being useful to take into account the extent to which mineral elements are not toxic to the body, the requirements of this category of cattle, as well as the mineral elements content in the forages from the rations structure.

The need of dairy cows in macroelements, namely in calcium and phosphorus, is determined based on the body weight, on the milk production level and on the physiological state.

For maintenance need was established as being 5 g calcium and 5 g phosphate / 100 kg live weight. The addition of macro-elements for the milk secretion is of 3 g calcium and 2 g phosphate / l of milk. The phospho-calcium ratio is recommended to be approximately 1 / 1.6, and for cows with high milk production of 1 / 1.2.

Ruminants exhibit increased requirements in terms of sodium chloride (salt) consumption, the more susceptible being the diary cows. The maintenance amount is, on average, 5 g of NaCl / 100 kg LW, and for production is of 2 g NaCl / liter of milk.

Potassium is found in sufficient quantities in the vegetal forages, in a proportion of more than 2.5% of the DM, which makes the appearance of gaps at diary cows be very rare.

The necessary magnesium for maintenance is on average of 2 g Mg / 100 kg LW, and for the production it is of 1 g Mg / liter of milk. The magnesium deficiency, associated with the calcium one, can cause at dairy cows the appearance grass tetany. This condition occurs mostly in early spring when the animals are out to pasture, the young plants being characterized by a high level of potassium and proteins, which determine a decrease in the absorption of magnesium in the body.

Iron, copper and cobalt are micronutrients of little importance for dairy cows, the lack is manifested only in the areas with poor soil in iron, sandy soils, with peat, where plants have poor content of these elements. It has been established that an iron requirement for dairy cows is of 50-100 mg / kg DM of ration, for copper 10-20 mg / kg DM of ration and cobalt 0.10-0.60 mg / kg DM of ration.

Selenium is recommended to ensure the amount of 0.30 mg / kg DM of ration. Deficiencies may occur in areas with poor soils in selenium, which determine the obtaining of plants under 0.10 ppm selenium content.

The amount of iodine from the ration influences the milk content of this microelement, easily crossing the breasts barrier. The needs of iodine of dairy cows are recommended to vary between 0.2 and 0.8 mg / kg DM of ration. The deficiency in iodine causes placental retention in dairy cows, infertility, reduced milk production, as well as the decrease of the milk fat percentage.

Therefore, in order to provide the necessary minerals for diary cows, it is recommended the use of mineral forages in the concentrate mixtures, as well as mineral premixes or briquettes.