Modeling and prediction accuracy of ammonia gas emissions from feedlot cattle

Objective: The objective was to develop an equation to indirectly predict the effect of feeding Experior (TM) (lubabegron; Elanco Animal Health, Greenfield, IN) on ammonia gas emissions (AGE) from cattle in subsequent feedlot studies. Materials and Methods: Our approach was to develop a prediction equation [the Elanco Ammonia Gas Emission Prediction Model (EPM)] using data from a 91-d clinical efficacy study in which lubabegron was fed to cattle housed in a cattle pen enclosure system and compare the precision and accuracy of the EPM with the precision and accuracy of a published equation that was developed to predict AGE from open-air feedlots. Results and Discussion: The evaluation of the published equation used to predict daily AGE (g/animal) resulted in poor precision (R-2 = 0.329) but reasonable accuracy (prediction bias = +14.8%). The developed EPM equation explained 98.7% of the variation in observed log 10 of cumulative AGE in the clinical efficacy study. Implications and Applications: The EPM explained 58.9 to 84.9% of the variation in cumulative AGE in 2 evaluation data sets, with a prediction bias of +0.13 to +18.6%. These data suggest that the EPM derived from the development data set using the cattle pen enclosure measurement system showed great promise to accurately and precisely predict cumulative AGE in future feedlot studies.