Date of this Version
Total collection data from many universities were pooled for statistical analyses to evaluate existing data from dairy animals and determine if one or more modifications were needed for Standard Table D384.1. Many of these studies were carried out to evaluate nutritional characteristics associated with different diets. The data collected were sufficient to evaluate total manure, total and volatile solids, and N excretion values. Some experiments had sufficient number of samples analyzed to evaluate P, K, Ca, Mg, Na, Cl, S, and micro-elements. Statistical analyses were conducted to determine if a single column value was appropriate and define the regression equations necessary to estimate excretions if the assumptions of the column inputs were not met.
The results indicate that separate classifications are needed for replacement heifers and mature animals. Final classifications for replacement heifers included: milk fed calves, weaned calves weighing less than 274 kg, heifers weighing between 273 and 613 kg, and veal calves. Additionally, classifications for lactating and dry animals are needed. Previously, the estimates for manure production and nutrient excretion were based on body weight. These findings indicate that a better predictor for lactating cattle is daily milk production instead of body weight. Milk production drives feed intake in the lactating animal. It is most appropriate that estimated manure and nutrient excretion values reflect the relationship between feed intake, milk production (nutrient utilization) and nutrient excretion.