VIII. EFFECTS OF DEFICIENCY 297 



grew as rapidly as chicks on a mash diet and showed a much lower mortality. 

 In chicks, fat deficiency is sometimes associated with subcutaneous edema, 

 and in a few cases general edema in the body cavity was observed. The 

 deficient birds were unthrifty and had poor feathering (Fig. 9). Removal of 

 yolk sacs from the newly hatched chicks did not seem to affect the develop- 

 ment of the deficiency. 



4. Mouse 



Mice kept on a fat-deficient diet develop the same general symptoms as do 

 rats.'^ The first symptom to appear is a dandruff -like dermatitis on the scruff 

 of the neck, which spreads over the animal. The dermatitis is followed by 

 necrosis of the extremities, and hematuria is observed in a few cases. 

 Decker et al.^^ have shown that adult mice can be brought to a state of 

 chronic essential fatty acid deficiency without showing any external sjonp- 

 toms, and that in these animals acute symptoms may be brought out by 

 stresses such as injuries, pregnancy, and x-irradiation. Although most 

 studies in the field of essential fatty acid nutrition and metabolism have 

 been carried out upon rats, it would seem that the mouse could effectively 

 replace the rat as an experimental animal because mice develop deficiency 

 symptoms more cjuickly, consume less food, and require less space. 



5. Large Animals 



No conclusive work has been done on the essential fatty acid require- 

 ment of large animals because of the tremendous cost of such experimenta- 

 tion. Cows require a minimum of 4% extractable fat in the diet for milk 

 production,'^' -" and calves on a low fat diet do not thrive.-' However, no 

 evidence has been brought out to relate these observations to essential 

 fatty acid requirements. Hogs on a low fat diet have a drastically reduced 

 linoleic acid content, but no deficiency symptoms have been observed.--"-* 



All the vertebrates in which fat-deficiency symptoms have been produced 

 experimentally have straight alimentary canals. In the author's laboratory, 

 attempts to develop fat deficiency in guin3a pigs failed, although many 

 animals were maintained on a fat-free diet for periods of time longer than 



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(1943). 

 18 A. B. Decker, D. L. Fillerup, and J. F. Mead, J. Nutrition 41, 507 (1950). 

 •« G. Gibson and C. F. Huffman, Michigan Agr. Expt. Sta. Quart. Bull. 244, (1939). 

 20 L. A. Maynard, K. R. Gardner, and A. Z. Hodson, Cornell Univ. Agr. Expt. Sta. 



Bull. 722 (1939). 

 2> T. W. Gullickson, F. C. Fountaine, and J. B. Fitch, /. Dair7j Sci. 25, 117 (1942). 

 " N. R. Ellis and O. G. Hankins, J. Biol. Chem. 66, 101 (1925). 

 " N. R. Ellis and H. S. Isbell, J. Biol. Chem. 69, 219 (1926). 

 2^ N. R. Ellis and H. S. Isbell, J. Biol. Chem. 69, 239 (1926). 

 25 N. R. Ellis and J. H. Zeller, /. Biol. Chem. 89, 185 (1930). 



