The B-vitamin content of milk in relation to breed of cow and stage of lactation

Microbiological methods were used to measure biotin, nicotinic acid, pantothenic acid, riboflavin, ‘vitamin B 6 ’ and vitamin B 12 in milk from Guernsey, Friesian and Shorthorn cows. 2. A study was made of day-to-day variations and breed differences in the B-vitamin content of such milk. Fluctuations in each vitamin were observed from one day to the next in milk from individual cows, these variations being especially marked with biotin and vitamin B 12 . In addition, the variations in the mean vitamin levels of milk from cows of the same breed were generally greater than any breed difference. 3. Samples of milk from ten Friesian and ten Shorthorn cows were taken at intervals throughout one complete lactation and analysed for each of the vitamins mentioned above. The results of this study of lactational trends are presented in detail.