title: Monthly variation and distribution of erythrocyte Na, K and Mg concentrations in normal dairy cows.
abstract: Blood samples were taken from the caudal vein of 64 normal dairy cows monthly for 12 months and the concentrations of erythrocyte Na (ENa), erythrocyte K (EK), and erythrocyte (EMg) were determined. The overall range of ENa concentrations in the cows was 16 to 176 mmol/l red cells with a grand mean (+/- SD) of 96 +/- 15.4 mmol/l, and a positively skewed distribution with a degree of skewness of 4.4. The overall range of EK concentrations was 13 to 99 mmol/l, with a grand mean (+/- SD) of 32.8 +/- 13.12 mmol/l red cells, and a distribution which suggested bimodality with modes at 26 and 70 mmol/l red cells. The overall range of EMg concentrations was 0.1 to 2.6 mmol/l red cells with a grand mean (+/- SD) of 0.99 +/- 0.12 and mode and median of 0.97 mmol/l red cells; the distribution was that of a normal Gaussian curve. Analysis of variance showed significant effects with respect to cows and calendar months but not lactation months on all cations (all P less than 0.01). The calendar months effects were similar for cows with mean erythrocyte K concentrations below 35 mmol/l for Friesians and Jerseys but not for Australian Illawarra Shorthorn cows. The repeatabilities were 0.4, 0.9 and 0.2 respectively for ENa, EK and EMg. It was concluded that ENa had a moderate genetic component, EK a high, and EMg a low genetic component. There was no significant correlation between plasma Na and ENA or plasma K and EK, but there was between plasma Mg and EMg (r = 0.21, df = 307, P less than 0.01).
authors.affiliation: Department of Physiology and Pharmacology, University of Queensland, Australia.
authors.forename: D C
authors.initials: DC
authors.lastname: Fenwick
authors.forename: R C
authors.initials: RC
authors.lastname: Daniel
mesh_terms: D000818:Animals; D002417:Cattle / Q000097:blood*; D004912:Erythrocytes / Q000737:chemistry*; D005260:Female; D008274:Magnesium / Q000097:blood*; D011188:Potassium / Q000097:blood*; D012016:Reference Values; D012621:Seasons; D012964:Sodium / Q000097:blood*
chemical_list: D012964:Sodium; D008274:Magnesium; D011188:Potassium