Abstract
The content of vital elements in the blood of animals can depend on a complex of factors, which include both the individual characteristics of organisms and environmental factors. It is interesting to study the effect of animal age on the blood mineral profile, however, taking into account possible differences in the chemical composition of feeds in different periods, an adequate assessment of the mineral profile on the same animals does not seem correct. The aim of the research was to study the differences in phosphorus, calcium, sodium and iron content in the blood serum of cows and heifers of the Hereford breed belonging to two adjacent generations. The material for the study were blood samples taken from 79 pairs of animals (motherdaughter) kept in the same conditions. As a result of the research, significant age differences in mineral status were established. The daughter generation (heifers) showed a higher phosphorus content (2.08 mmol/L versus 1.68 mmol/L in mothers; p = 0.0036) and, as a result, a lower Ca/P ratio (p = 0.0094). On the contrary, the sodium concentration was significantly higher in the maternal generation (median 179.70 mmol/L versus 144.60 mmol/L in daughters; p = 0.0001). No significant differences in the content of calcium and iron were found. The Principal Component Analysis (PCA) has confirmed that the main vector of variability between generations is related to calcium-phosphorus metabolism. At the same time, a significant overlap of the concentration ellipses indicates a high individual variability of the mineral profile, unrelated to the age. Thus, the results obtained indicate multidirectional age-related changes in the metabolism of key macronutrients. This justifies the need to adjust the mineral composition of diets and premixes for Hereford breed animals, taking into account their age (generation) in order to maintain physiological health and productive potential.