A U.S. Patent Application for “Feed Media” was published by Amgen on March 12th, 2020. The present invention is a method for stabilizing a concentrated feed medium for feeding a mammalian cell culture comprising including in the feed medium at least about 9 mM pyruvate, wherein the feed medium comprises cysteine and/or cystine, wherein the sum of the concentrations of cysteine and/or cystine is at least about 7.9 mM, wherein the pH of the feed medium is from about 5.8 to about 7.4, wherein the feed medium comprises tyrosine and the tyrosine concentration is not more than about 4.4 mM, and wherein the feed medium with the included pyruvate is stable… Learn More