ANNUAL REPORT, 1945-46 25 



of each flavor of ice cream were assayed. The carotene content was 0.10 mg. per 

 100 gm.; the riboflavin, 0.26 mg. per 100 gm. No reduced ascorbic acid could 

 be detected in any samples, probably owing to destruction by the large amount 

 of air incorporated in commercial ice cream to increase its bulk. Comparison of 

 these ice creams with numerous widely used foods, showed them to be excellent 

 sources of carotene and riboflavin. Since the average yearly consumption of ice 

 cream is estimated at three gallons per person, it contributes significant amounts 

 of carotene and riboflavin to the human dietary. 



The Vitamin Content of Mare's Milk. (Arthur D. Holmes, Beula V. McKey, 

 Anne W. Wertz, Harry G. Lindquist, and Leonard R. Parkinson.) This in- 

 vestigation was undertaken to compare the composition of cow's milk and mare's 

 milk — two species of animals that consume the same type of ration, but possess 

 different types of digestive tracts. Studies have shown that the vitamin content 

 of cow's milk is likely to be due in part to vitamins produced by bacterial syn- 

 thesis in the cow's rumen, but the mare has no rumen. This, the initial paper of a 

 proposed series, reports the results of assays of mare's milk for ascorbic and 

 nicotinic acids, riboflavin, thiamine, bacteria, fat, size of fat globules, and total 

 solids. Three normal, adult Percheron brood mares, in the latter stages of lacta- 

 tion, were used as a source of the milk. Eleven samples of fore-milk were ob- 

 tained from each mare in the early morning. The average values obtained were: 

 ascorbic acid, 12.9 mg.; nicotinic acid, 0.72 mg.; pantothenic acid (3 samples,) 

 2.77 mg. ; riboflavin, 0.11 mg. ; thiamine, 0.39 mg. per liter; bacteria, 3.70 per 

 cc; fat, 1.2 percent; fat globule size, 3.4 microns; and total solids, 10.20 percent. 

 The values for ascorbic acid, nicotinic acid, riboflavin, fat, and total solids were 

 lower than the corresponding values for milk from cows that consumed the same 

 pasturage; but the thiamine values were higher. The greatest difference in 

 vitamin content between mare's and cow's milk was in riboflavin. As yet, it is 

 impossible to explain why the former has much less than one tenth as much ribo- 

 flavin as the latter. 



A Study of the Changes in Vitamin Content Coincident with Different Stages 

 and Rates of Maturity of Vegetables Used for Home Consumption. (Arthur D. 

 Holmes and Carleton P. Jones.) During the past year published results from 

 the studies in this field have been concerned with kale and summer squashes 

 grown under local climatic and cultural conditions, and supply information of 

 particular value regarding the value of these vegetables for the human diet. 



Influence of Supplementary Calcium and Magnesium Fertilizers Upon Nutritive 

 Value of Kale. (Arthur D. Holmes, Leo V. Crowley, and John W. Kuzmeski.) 

 The kale was grown on a Merrimac fine sandy loam in four experimental plots, 

 all of which received a commercial 4-9-7 fertilizer at the rate of one ton per acre. 

 In addition, the experimental plots received varjing amounts of magnesium 

 sulfate, ground limestone, or both, with one plot serving as a control. Twenty 

 samples of kale were assayed for water, calcium, iron, magnesium, phosphorus, 

 and carotene. The addition of 150 pounds of magnesium sulfate per acre def- 

 initely increased the magnesium content of the kale and may have slightly in- 

 creased the calcium and phosphorus content. Limestone, applied at the rate of 

 1,000 pounds per acre, definitely increased the calcium and phosphorus content 

 of the kale and may have depressed its iron content. Neither magnesium sulfate 

 nor limestone nor both produced any pronounced effect on the water or the caro- 

 tene content of the kale. As compared with other leafy vegetables kale is rich 

 in carotene, the precursor of vitamin A. Judged by the results of this study, the 

 use of magnesium sulfate and limestone as supplementary fertilizers enhances 

 the food value of kale. 



