In a study of the average ascorbic acid content of milk produced by a mixed dairy herd, Rasmussen, Guerrant, Shaw, Welch and Bechdel1 found that the ascorbic acid content of milk was "relatively high during the early stages of lactation, but decreased to a minimum, after about two months of lactation, and then increased to a maximum in the later stages of lactation." These authors also reported that the ascorbic acid content of milk varies with breeds of cows, being 50 per cent greater for Brown Swiss than for Holstein cows, and it appears from their data that the proportion of milk from cows of each of the five breeds under observation was not uniform for all the mixed milks assayed at the thirteen monthly periods.
Whitnah and Riddell2 reported that during the first month of lactation milk has about a 10 per cent lower vitamin C content
HOLMES AD, TRIPP F, WOELFFER EA, SATTERFIELD GH. ASCORBIC ACID CONTENT OF COW'S MILK AT VARIOUS STAGES OF LACTATION. Am J Dis Child. 1940;60(5):1025-1030. doi:10.1001/archpedi.1940.02000050009002