(1) Further experiments are described, the results of which support the relationship between the presence of vitamin A in the diet of the cow and its presence in milk fat.
(2) The typical winter ration of concentrates, roots and hay may be adequate to maintain the vitamin A value of the milk fat for considerable periods provided that at least one of the components supplies adequate amounts of that dietary principle. Well cured green meadow hays are in this respect greatly superior to dry brown seeds hays.
(3) The addition of cod liver oil to a winter ration deficient in vitamin A will induce a sharp rise in the vitamin A value of the milk fat of cows. No such effect is seen when oils deficient in this dietary factor (coconut oil, arachis oil) are given.
(4) The administration of cod liver oil in doses from 1 to 8 ozs. daily to milking cows caused no “fishy” taint in the milk or butter-fat.
(5) The administration of cod liver oil caused no appreciable change in the yield of milk but the higher doses appeared to cause a noticeable drop in the percentage of fat. Further experiments are required to throw more light on this observation.