[Analyses of the relationship between the concentrations of essential trace elements in total mixed ration and faeces samples from Holstein Friesian dairy cows and the estimation of faeces reference values].

Introduction: Undersupply and oversupply of dairy cows with essential trace elements should be avoided from the point of view of animal health and environmental pollution. The aim of the study was to proof the results faecal analyzes on the nutritional supply situation with essential trace elements in comparison to measurements from total mixed ration (TMR) analyses. Concentrations of iron (Fe), copper (Cu), zinc (Zn), Mangan (Mn), selenium (Se), cobalt (Co), molybdenum (Mo) were measured as representative multicentric random sample in 574 TMR, 600 pooled faecal and blood samples from dairy cows. Trace elements, Fe in 0 %, Se 18 %, Zn 43 %, Cu 52 %, Co 53 % and Mn 59 %, were within the target range. Undersupply was found in 0 to 8 % and an oversupply in 39 to 100 % of the TMR samples. The tolerance limit for Fe was exceeded in 11 % and for Mo in 13 %. The results indicate the need for optimized ration design. The trace element concentrations in the faecal samples varied over a wide range. Results of pooled faecal samples (n=10 per pool) corresponded closely with the mean values calculated from the individual samples (r2 > 0,9). Correlation between element concentrations in the TMR and faecal samples for Fe (r=0,687), Cu (r=0,675), Zn (r=0,635), Mn (r=0,656), Se (r=0,573), Co (r=0,795), and Mo (r=0,708) were highly significant. No correlations were detected between the element concentrations in the TMR and in the blood samples. The regression analyzes showed a highly significant linear adjustment of the measured value distribution around the regression lines over the entire value range including the zero point. Reference values were calculated for the faecal concentrations of Cu, Zn, Mn, Se and Co. Tolerance reference limits in the TMR were calculated for the faecal concentrations of Fe and Mo. The trace element concentrations in the TMR samples reflect the nutritional supply situation. Knowledge of the nutritional supply situation of the herd is of great importance for the stock management of dairy cow. Fecal sample analyzes can be used as an alternative to TMR examinations to assess the nutritional supply situation.