Objectives: Renal function tests were performed on 38 clinically healthy Holstein calves aged 1435 days, of which seven had survived bovine neonatal pancytopenia (BNP). The main objective was the establishment of reference values for renal fractional excretions (FE) of sodium (Na), potassium (K), calcium (Ca) and phosphate (P) in calves fed milk replacer. Additionally, it should be clarified whether calves suffer from permanent renal disorders as a result of BNP.
Material and methods: The fractional excretions were determined using wet chemical analyses of simultaneously taken urine and blood samples. Their calculation was based on the endogenous excretion of creatinine.
Results: There were no significant differences in the FE between calves with and without a history of BNP. Based on the values of all 38 calves, reference values were calculated for the FE indicated above, and also for the urinary γ-glutamyltransferase-creatinine ratio as a parameter for the damage of tubular cells.
Conclusion: It has been demonstrated that age- and feeding-specific reference values for renal function parameters in cattle are necessary. For renal function analyses in calves, the nutritional supply with electrolytes has to be considered to differentiate the variability of electrolyte excretions due to different feeding regimes from renal disorders. Based on the calculated reference values for calves fed milk replacer, renal function disorders can be determined sensitively and further differentiation is possible.
Keywords: Calf; electrolytes; fractional excretion; urine.