Prediction of urinary output from pasture-fed dairy cows

Abstract

Prediction equations using easily acquired measurements could offer an estimate of urinary nitrogen output (UNO), therein helping to refine nutrient management on dairy farms. However, there is little evidence regarding the validity of currently used equations for pasture-based diets. Using a dataset derived from a pasture-fed cow study, five published equations were evaluated for their usefulness in predicting UNO. Results indicated large variability in prediction accuracy (r²=36.8 - 77.5). A new prediction equation that achieved higher prediction accuracy was established (r²=84.4).