Seasonal variation of carotene and vitamin A in butter-fat and in serum

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

Section: Vitamin Dmentioning

confidence: 57%

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

Thompson¹,

Henry²,

Kon³

1964

“…In a few cases (e.g. Lord (5), who also briefly reviews previous work) plasma and milk fat levels have been followed on the same cows at the same time, and it is apparent that the milk fat reflects fairly closely the changing levels in the plasma. While the seasonal trends in New Zealand milk fats cannot be ascribed to changes in the carotene intake (3), it seemed of interest to determine whether these somewhat unusual variations were also associated with similar changes in the level of vitamin A and carotenoids in the blood plasma.…”

Section: (With 5 Figures)mentioning

confidence: 99%

657. Factors influencing the vitamin content of milk fat: III. Seasonal changes in the vitamin A and carotenoid content of the blood plasma and milk fat of cows on pasture

McGillivray

1957

1. The levels of vitamin A alcohol and ester, carotene and xanthophyll in the blood plasma of six cows, grazed out-of-doors on pasture under typical New Zealand conditions, have been followed throughout one lactation. The same constituents have also been followed in the milk fats of these animals and in commercial factory butters over the same season.2. The seasonal trend in the vitamin A and carotenoid content of New Zealand milk fat is a reflexion of the changing level of these substances in the blood plasma.3. The decreased level of carotene, xanthophyll and vitamin A ester in the blood plasma over the summer months is consistent with a decreased absorption or utilization of carotenoids over this period.4. Throughout the year the vitamin A in the milk fat is predominantly in the ester form with no increase in vitamin A alcohol indicative of any increased utilization of hepatic vitamin A reserves.The author is indebted to the Department of Scientific and Industrial Research for a grant towards this investigation; to Mr M. R. Patchell and the farm staff of The Dairy Research Institute (N.Z.) for assistance in the collection of milk and blood samples; to Dr F. H. McDowall, Mr A. K. R. McDowell and the staff of the Chemistry Laboratory, The Dairy Research Institute (N.Z.), for the preparation of the fat samples and for the supply of factory butters. The assistance of Miss Fay Frecklington and Miss Jane Monroe with part of the experimental work is also acknowledged.

“…Over long periods clear relationships have been established between the levels of carotene in the blood plasma and the milk fat (e.g. (3,13)). Over the short period reported here, however, the marked drop in milk fat carotene (Fig.…”

Section: (1) Effect Of Carotene-free Dietmentioning

confidence: 99%

658. Factors influencing the vitamin content of milk fat: IV. The source of milk fat vitamin A and carotene

McGillivray

1957

With 2 Figures)'During the course of investigations into factors affecting the vitamin content of New Zealand milk fats(i, 2,3) the need for further information about the source of the milk fat vitamin A and carotene became apparent. Experiments were therefore carried out to investigate the relationship between the levels of carotene and vitamin A ester in the blood plasma and milk fat, and to assess the relative contributions of vitamin A of hepatic origin (through the blood plasma vitamin A alcohol) and vitamin A of immediate dietary origin (through the blood plasma vitamin A ester) to the vitamin A content of the milk fat. It is well recognized that for the production of milk fat of high vitamin A potency, cows are more dependent on a daily carotene or vitamin A intake than on liver reserves of vitamin A (e.g. (4)). For other species, relationships between dietary and milk fat vitamin A have been studied (e.g. (5)) and aspects of the problem have recently been investigated in cows by Chanda and co-workers(6,7,8). It seemed, however, that further information obtained under New Zealand conditions would enable a more precise interpretation of the seasonal variations already reported (3,9,10,11) in the levels of vitamin A and carotenoids in the milk fat and blood plasma of pasture-fed cows in this country. EXPERIMENTALThe cows used were predominantly Jersey from the herds of The Dairy Research Institute (N.Z.) and Massey Agricultural College. Unless otherwise stated, all cows were milked normally twice daily, milk samples being collected at the evening milking.In the first experiment, carried out in December, two cows, which had been fed normally on pasture, were brought indoors and fed, for 11 days, a carotene-free diet consisting of linseed meal, crushed oats and bran in equal quantities and straw ad lib. as roughage. At the end of this period they were returned to pasture. Milk and blood samples were taken throughout the experiment.In the second experiment, carried out in August, the effect on the milk fat levels of a single dose of vitamin A was investigated. The cows were on pasture throughout the experiment and were dosed orally with varying levels of vitamin A.* Milk samples were collected at intervals and, in the case of one cow, simultaneous milk and blood samples were taken at frequent intervals following the dose of vitamin A. * The vitamin A was administered as an emulsion supplied by Nicholas Products Ltd., Wellington, and containing approximately 8 mg. vitamin A per gram.