Metabolic and cellular profile testing in calves under feedlot conditions, using discriminant analysis to identify calves with low potential for weight gain.

Thirty-eight variables were measured in blood samples of 48 calves at the beginning (day 0) of a feed trial. After 56 days, the calves were assigned (according to weight gain) into three groups: high gainers, medium gainers, and low gainers. Discriminant analysis was used on the variables that were measured to classify the calves into three groups. When the mean values for three overlapping groups of 16 calves each were analyzed, blood urea nitrogen data alone correctly classified 68.7% of the low gainers. Overall, correct classification never exceeded 58.3%. When three nonoverlapping groups of nine calves each were used, inorganic phosphate data (used first and alone) correctly classified 66.7% of the low gainers. After seven steps, 81.5% of the animals were correctly classified, including 88.9% of the low gainers. The two-group discriminant analysis identified 78% of the nine lowest gainers, and 90% of the remaining animals were correctly classified.