Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

In the absence of actual biological data on total excreted nutrients, development of models is needed to predict these values. Models are usually constructed based on relationships that have been determined biologically and that allow for estimation of values. Estimation of nutrient excretion has become necessary due to the recent emphasis on environmental management and regulation of animal feeding operations. Because of the impact that new environmental regulations will have on animal production it is important to determine if model estimates are accurately predicting biological nutrient excretion rates. A broiler chick total excreta collection by age period trial was conducted to determine actual excretion of dry matter (DM), nitrogen (N) and phosphorus (P). Values obtained in this trial were compared to the latest broiler model developed and proposed by the American Society of Agricultural Engineers (ASAE). The new proposed ASAE model overestimates DM, N and P excretion by 19.4, 14 and 13%, respectively as compared to numbers obtained from a total collection trial in broiler chicks up to 2.36 kg of body weight fed an average industry diet. The apparent overestimation in nutrient excretion levels in the proposed ASAE model reflects variability inherent at the commercial production level. These overestimations are within what would be expected when average production levels (variable) are being used compared to levels obtained from one controlled battery trial.