Factors affecting the concentration of vitamins in milk: I. Effect of breed, season and geographical location on fat-soluble vitamins

Abstract

TWO surveys were done, one in 1943-44 and one in 1958-60, of the seasonal variation in the concentration of vitamin A and carotene in milk fat from 13 different areas in Great Britain. In the 1958-60 survey a-tocopherol and vitamin D were also measured. The main purpose of the second survey was to find out if the marked swing from Shorthorns to Friesians, and the trend towards greater use of carotene-rich foods in winter feeds that occurred in the intervening 15 years, had affected the pattern of vitamin A activity. In addition, monthly samples of butter were obtained in 1958-59 from a single factory in New Zealand during a complete butter-making season (9 months) and were assayed for vitamin A, carotene, a-tocopherol and vitamin D. Three experiments were done to study the effect of breed on the vitamin A and carotene content of milk fat, and in one of them a-tocopherol and vitamin D were also determined.The seasonal trends for vitamin A and carotene were essentially the same in both surveys. A peak occurred in May after the spring flush of grass and was followed by a decline with a second peak in the autumn, except in 1959 when both the summer and autumn were very dry. Potencies were higher in the south than in the north, where the differences between summer and winter were more marked. In winter, mean vitamin A potencies of 5-8 and 7-7 jug/g fat were found for northern and southern areas, respectively; the corresponding values for jS-carotene were 2-0 and 4-5 ^ig/g fat. Mean summer values were 8-8 and 9-7 /xg/g fat for vitamin A and 5-1 and 6-5 /xg/g fat for carotene, equivalent to increases of about 52 and 26% and about 155 and 44%, respectively, over winter values. Differences in mean potency between areas are explained by length of grazing season and type of winter feed.The concentration of vitamin A in the fat was essentially the same for Ayrshires, Friesians, Jerseys and Shorthorns but somewhat lower for Guernseys; that of carotene was higher for the Channel Island breeds, particularly Guernseys, than for the other breeds studied.Compared with this country, concentrations of carotene were higher and of vitamin A lower in milk fat from New Zealand, probably because of the predominance of Jersey cows in New Zealand herds. The seasonal trends for these vitamins were similar in both countries, but the spring peaks were earlier, the autumn peaks later and the summer declines more pronounced in New Zealand than in this country.Concentrations of a-tocopherol in British milk fat showed a trend similar to that found for both vitamin A and carotene and were again influenced by feeding practices. 1 Dairy Res. 31

Selection and segregation of herds for a valuable milk trait

“…The milk fat colour curve (Fig. 1, Winkelman et al, 1999) adapted to predict the mid-point of each period as a percentage of the lactation day one value was similar to those recorded for New Zealand bulk milk (McDowell and McDo- well, 1953; Thompson et al, 1964;Keen, 1986;Keen and Wilson, 1993).…”

Environmental and genetic factors influence the vitamin D content of cows’ milk

“…Evidence suggests that this seasonal variation is the result of insufficient stores of vitamin D in the liver and fat tissues for mobilisation in times when dietary intake of the vitamin is low (18) . Many subsequent studies have confirmed the seasonal variation of the vitamin D content of milk (approximate differences ranging between 0•004 and 0•0014 µg/g fat) across different countries and breeds of cattle (Table 1) (19)(20)(21)(22) . Although seasonal variation in vitamin D content is widely reported in the literature, units of measurement are inconsistent, which makes it difficult to compare between studies.…”

Relationships between the conditions of cow’s milk production and the contents of components of nutritional interest in raw milk farmhouse cheese

“…The xanthophyll and β-carotene contents in cheese fat were the richest with the Montbéliarde breed and the poorest with the Abondance breed, respectively. Several studies have previously observed an effect of the cow's breed on the carotenoid content in milk fat [29,41,65,71], but none have experimentally compared these three breeds to our knowledge. The variations in the carotenoid content in milk fat related to the cow's breed could be due to differences between breeds of: (1) intestinal conversion of β-carotene into retinal by the 15, 15' dioxygenase [29], (2) quantitative secretion of β-carotene from plasma into milk [37] and/or (3) β-carotene storage and mobilization [67].…”