An improved method is provided for treatment of feed water for livestock and other animals to reduce bacterial contamination while at the same time improving live performance. A gaseous mixture comprising ozone and oxygen gas is produced from ambient air and directly contacted with a supply of water to produce a solution of gaseous mixture. This contact step is continued until the content of ozone in the water supply is within a range of from about 5 parts per million to about 20 parts per million, and the content of oxygen is between about 80% and 97% of saturation. Thereafter, the resultant water product is directed for use as feed water to livestock or other animals to be treated.