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Effect of fat on the vitamin K requirement of the chick. Davies, Ronald Edgar


A study has been made of the relationship of dietary fat to the vitamin K requirement of the chick. In these experiments, the vitamin K status of chicks was measured by determining the blood "prothrombin time" by the method of Quick (1936) as modified by Almquist (1941). It was possible to produce a "prothrombin deficiency" in chicks by feeding diets which consisted of unextracted natural ingredients. The extent of this deficiency was affected by the maternal supply of vitamin K. In some cases the coagulation defect was sufficiently severe to cause fairly heavy mortality from haemorrhaging. Certain fats, when added to the diet, protected the chick from a vitamin K deficiency. Beef tallow, hydrogenated cottonseed oil, and to a lesser extent cottonseed oil and hydrogenated animal fat all shortened blood "prothrombin time" of chicks, when added to a vitamin K deficient diet. These fats prevented the haemorrhaging which sometimes resulted from vitamin K depletion. Herring oil generally did not shorten "prothrombin time" unless the vitamin K deficient diet was also deficient in folic acid. The effect of fats on "prothrombin time" was apparently not due to the vitamin K content of the fat, nor to an increased absorption of vitamin K resulting from increased bile secretion. Oral administration of oils shortly before drawing blood did not affect "prothrombin time" of blood from vitamin K deficient chicks; this indicates that lipaemia per se did not cause the shortening in "prothrombin time" observed after feeding a high-fat diet. Free fatty acids added to a vitamin K deficient diet did not affect "prothrombin time" to a significant degree. Addition of choline to a vitamin K deficient diet did not affect "prothrombin time". This observation agrees with those of field and Dam (1945) but disagrees with those of Honorato and Moline (1942). the addition of methionine also failed to affect "prothrombin time". Herring oil also has a shortening effect when added to such a diet, but not when added to a diet containing adequate folic acid. Cholic acid added to a vitamin K deficient diet caused a lengthened "prothrombin time." Desoxycholic acid had a similar effect in one test, but had no effect in another case. Injection of chicks with the surface active agent Triton WR-1339 likewise lengthened "prothrombin time." Triton had no effect, however, when added to blood in vitro. Breast muscle and brain tissue differed in the thromboplastic properties of their extracts. The breast muscle preparation required the addition of phospholipid for maximum thromboplastic activity. Acetone partly extracted and partly destroyed the thromboplastic agent of breast muscle, but did not affect that of brain tissue. Although bile salts may affect blood phospholipid levels, their effect on blood "prothrombin time" was not due to the sensitivity of the breast muscle thromboplastic agent to phospholipid. The "prothrombin time" of blood, as determined with breast muscle thromboplastic agent, is not necessarily a measure of the vitamin K supplied to the chick.

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