IX. REQUIREMENTS 445 



the parent hen was important in the survival of the chick on a K-deficient 

 diet and in controlling the blood-clotting time of the day-old chick." These 

 observations showed a transfer of the vitamin from the hen diet to the chick. 

 Alfalfa meal in the hen diet at a level of 2.5 % was sufficient for protection 

 of the chick. The vitamin was found in egg yolk but not in egg white. 

 Certain indications'* that the prothrombin content of chick blood rises for 

 the first 3 or 4 days of life despite very low vitamin K intake may have 

 been due to assimilation of vitamin K remaining in the unabsorbed yolk 

 which normally is present in the chick for some time after hatching. Cravens 

 et al} have also found that the blood-clotting time and prothrombin content 

 of day-old chicks is dependent upon the vitamin K content of the ration 

 fed the parent hen. One to two per cent of dried alfalfa or grasses was 

 required in the hen diet to maintain a normal prothrombin content in the 

 day-old chick. In these studies^- ^ higher intake by the hen of vitamin K 

 in the form of dried greens had little or no further effect on the chick. 



Tidrick et al.^ injected 2-methyl-l , 4-naphthohydroquinone disulfate into 

 hatching eggs and obtained chicks with superior reserve stores of vitamin 

 K, as indicated by retention of prothrombin levels in the chicks when fed a 

 vitamin K-deficient diet. 



On constant submarginal levels of vitamin K in the diet chicks tend to 

 show a progressive increase of blood clotting time up to approximately two 

 weeks of age and then a decrease.-' ^' ^ At this age the hemoglobin level of 

 chicks, even on a normal diet, passes through a minimum phase and begins 

 to increase again. The riboflavin requirement is probably at a maximum. 

 After 2 weeks the gain in weight per unit weight of food consumed decreases, 

 and the food intake of vitamins in reference to the weight of the bird begins 

 to increase. The age of 2 weeks appears to be a sensitive, if not critical, 

 physiological stage of the chick. It is evident, therefore, that the vitamin 

 K intake required to maintain any particular clotting time would vary 

 with the age of the chick over the first 2 to 3 weeks of life. However, the 

 vitamin K requirement does not seem to be related to the body weight of 

 the chick. ^ 



If the vitamin K-deficient chick is given a sufficiently large dose of the 

 vitamin the clotting time or prothrombin time can be restored in 4 to 6 

 hours.^'^" 



2 H. J. Almquist, E. Mecchi, and A. A. Klose, Biochem. J. 32, 1897 (1938). 



3 F. W. Stamler, R. T. Tidrick, and E. D. Warner, J. Nutrition 26, 95 (1943). 



•• W. W. Cravens, S. B. Handle, C. A. Elvehjem, and J. G. Halpin, Poiiltv!/ Sci. 20, 



313 (1941). 

 * R. T. Tidrick, F. W. Stamler, F. T. Joyce, and E. D. Warner, Proc. Soc. Exvtl. 



Biol, and Med. 47, 438 (1941). 

 « H. J. Almquist and E. L. R. Stokstad, J. Nutrition 14, 235 (1937). 

 '' H. Dam, J. Glavind, L. Lewis, and E. Tage-Hansen, Skand. Arch. Physiol. 79. 121 



(1938). 



