Abstract: A method and apparatus whereby livestock and poultry are administered feed additives in their feed ration. The apparatus stores additive concentrates separately until just prior to use, then on demand dispenses the additive concentrates into one or more weigh hoppers for weighing therein. The weighed contents of the weigh hoppers are discharged into a liquid carrier within a mixing vessel where the dispensed additives are diluted, suspended, and dispersed by mixing. The resulting carrier-and-additive slurry is pumped to a receiving station for mixing with a feed ration. The weighing components are isolated from movements that would affect additive weight determinations during the weighing process so that accurate measurements of additive weights are obtained. Dispensing and weighing of multiple additives within a single weigh hopper are sequential. Each additive may be weighed and discharged from the hopper individually or cumulatively with other additives.