Factors relating to incidence of spontaneous oxidized flavor and copper in cow's milk

The incidence of spontaneous oxidized flavor (SOF) is commonly assumed to be dependent on the combination of substrate supply and contents of pro- and anti-oxidants in milk. A total of 142 cows in the experimental herd at the Swedish University of Agricultural Sciences were included, 87 of the Swedish Red breed and 55 of the Swedish Holstein breed. Altogether 893 milk samples were analyzed for milk composition, copper content, and milk flavor. Milk copper concentration was highest in early lactation and during the spring period. Oxidative off-flavor was most common during the first 3 weeks of lactation. However, when adjusting for copper concentration the odds ratio for incidence of SOF was instead highest in lactation weeks 14-39. The higher incidence of SOF during the first 3 weeks of lactation is proposed to be a consequence of the high copper concentration in milk during this period.