mammalian carotenoids 



Cheese 



Cheese undergoes the same seasonal variations in carotenoids as does 

 milk. ^ * ^ About 85 per cent, of the milk carotenoids are transferred to 

 the cheese i * 9, i b o ^nd these carotenoids persist through ripening. 

 Little difference was noted between carotene levels in Cheddar and 

 Cheshire cheeses, mean values 2-0 ^g. and 10[xg./g. of cheese fat for 

 winter and summer cheeses respectively ; ^ ^ ^ a typical value when 

 calculated on the whole cheese is 1-8 [xg./g. 1*^ 



The sharp fall in plasma carotenoid levels at parturition 1 », 1 4 0. 1 4 1, 

 16 2^ 16 2A ig stabilized for about three weeks post-partum when the 

 levels are about 46 per cent, of the pre-partum levels ; thereafter the 

 levels begin to increase (Fig. 32). The physiological factors controlling 

 this drop are not yet completely understood ; the claim of Sutton, 

 Kaeser and Soldner ^ * ' that the sharp decline coincides with a rapidly 

 filling udder, t.e., with the drawing off of colostrum cannot be the only 

 factor operating, because a similar fall occurred when a mammec- 

 tomised cow gave birth to a premature calf. ^ ^ ^ Goodwin and Wilson ^ ® • 

 consider that the changes have no significance for carotenoids per se^ 

 but merely indicate a general variation in the concentration of blood 

 constituents at parturition, for similar changes have been noted with 

 plasma lipids, ^ •* * Ca and P, 1 e 4, 1 b 6 vitamin E, ^ ^ * and cholesterol. ^ ' ^ 



It is interesting to note that the drop does not occur in cows which 

 develop milk fever. ^ ^ ^ In induced mastitis, however, the milk caro- 

 tenoid levels are increased but the total amount secreted per day is 

 always below average because of the lowered milk yield ; on recovery 

 the values returned to normal. ^ ^ ' Calves which were born with no 

 plasma carotenoids had 4-5-17-7 (xg./lOO ml. according to diet within 

 3-4 days of birth. At about 7 days this had dropped to a steady level. ""^ 



Spielman et al.^*^ found that foetal livers and blood contain caro- 

 tenoids and that the liver levels but not plasma levels were proportional 

 to the maternal intake of carotenoids. This is contrary to the work of 

 Lund and Kimble*^* on humans which demonstrated a direct correla- 

 tion between maternal and foetal plasma carotenoids. As has been 

 previously stated a normal plasma carotenoid level for a full-term 

 foetus is 22 (xg./lOO ml.i^o 



Factors other than dietary and reproductive can play some part in 

 controlling plasma carotenoid levels in cattle. For example, cows 

 with acetonaemia have high blood carotene accompanied by low vitamin 

 A levels. Massive doses of vitamin A cure the acetonaemia and 

 restore both the carotenoid and vitamin A levels to normal. ^ » ^- ^ " ® 

 A similar reaction to vitamin A therapy can be produced in normal 

 cattle ; massive doses of vitamin A reduce the plasma and milk 



243 



