Pasturing heifers from German Red Pied and German Holstein Frisian breed on pasture grounds not treated with nitrogen fertilizer

On 25 heifers (12 German Red Pied, 13 German Holstein Frisian) measurements of body weight and of blood components were performed at the end of the stalling period and repeatedly in the time the animals were on pasture. Blood samples (V. jugularis) were analysed for acid-base balance, hemoglobin content, hematocrite, MCHC, O2CONT, O(2)SAT, O(2)CAP, HHb, COHb, MetHb in whole blood and for total protein, albumin, creatinine, urea, Ca, Mg, P, Fe in blood plasma. For 19 out of 22 variables significant mean differences could be found between some sampling points. More profound changes concerned albumin, creatinine, urea, Ca, Mg, P, Fe, COHb, MetHb, pH, pCO(2), BE and HCO3 and less profound Hb, Hk, MCHC, total protein, O(2)SAT and HHb. Mean differences between pasture groups and breeds were evident at some measuring points. Ca, Mg, Fe and Hb and Ilk showed significant negative correlations with growth parameters at some sampling points. Strong correlations for creatinine, Fe, Hb, Hk, O2CONT and O(2)CAP between sampling points are an expression of individual specificity of these variables. Correlations of the changes of the variables with the starting value at the end of the stalling period show, that adaptation took place in an individual and time specific way concerning direction and degree. Results indicate variation causes of usually applied clinical-chemical blood measures in young cattle on pasture, which can be explained in relation with food availability and adaptation to environmental conditions and should be considered in setting and applying reference values.