[Normal values of various biochemical indicators in lowland black-white dairy cows from the government sector of the Gdańsk Coast. II. Effect of basic species-specific factors].

For the estimation of influence of cows age on ten biochemical blood parameters, the investigation results of 1889 cows were chosen and for the evaluation of influence of lactation phase, the investigation results of 982 cows were selected. The levels of glucose, protein, albumins, urea, chlorides, sodium, potassium, magnesium, calcium and inorganic phosphorus were investigated in cows of the age of 3-10 and above 10 years as well as at cows which were dried up and after that in the consecutive lactating months. It was established that the majority of parameters did not change in the process of cows growing old and in the lactation. The results of earlier investigations with the lack of features, so called, the productive metabolic overloading of cows in governmental farm herds, were confirmed. It was settled that a necessity exists for an introduction of the following reference values: 0.62 mmol/l for the lowest boundary of magnesium level in cows of the age above 9 years, from 1.32 to 2.20 mmol/l for the value range of inorganic phosphorus level in cows of the age above 6 years and from 1.36 to 2.10 mmol/l for the latter compound in cows in the first three months of lactation.