Disclosed herein is a method of sorting, treating, and feeding a group of bovine animals in a feed lot, wherein the method may include the steps of determining an ob genotype of each animal, comparing the relative weight and back fat of each animal with the other animals, dividing the animals into subgroups based on weight, back fat, and ob genotype. The same number of through electrodes are included in each of paths extending from a first power source terminal through each of circuit elements formed for the semiconductor chips to a second power source terminal. A transparent glue covers the light emitting diodes and copper foils are located on a rear side of the circuit board. The heating control unit controls the power of the heating by switching on and off of one or more half cycles of the mains AC voltage. In a preferred embodiment, the fluid is a reagent in a reagent pack used in a diagnostic analyzer.