Assessment of sodium and potassium levels in soil, feeds and hair of dairy cows in east-central Poland / Ocena poziomu sodu i potasu w glebie, paszach i sierści krów mlecznych z rejonu środkowo-wschodniej Polski

Studies were conducted on farm “A” located in east-central Poland to assess the mineral content in cows, taking into account individual links of the soil-feed-animal trophic chain. The mineral assessment included the determination of Na and K. Soil samples were taken once from the humus layer (that is at the depth of 0-15 cm) of pastures and arable fields in mid-growing season by means of a soil sampling stick. Feed samples were taken regularly when the feeds were included in rations (all year round), making sure the samples were representative. Sodium and potassium contents in soil and feeds were determined by the Atomic Absorption Spectrometry methods and in hair by the Inductively Coupled Plasma-Optical Emission Spectrometry method. There were two dates for hair sample collection: I (10-14 days prior to calving) and II (after the first month of lactation). The results showed that Na and K concentrations were sufficient to meet animal needs. The sodium level in cow’s hair fell within the physiological range. Also potassium concentration complied with the referential standards (2000 mg·kg^-1 d.m.) and approximated 2040 mg·kg^-1 d.m.