livers of fasted animals fed SPE diet than in 

 those of nonfasted rats, but the fat content re- 

 mained approximately the same whether or not 

 the rats were fasted prior to sacrifice. 



Although the percentage of liver fat among 

 individual rats varied considerably, the livers from 

 stock or SP 8 HVO rats were not considered 

 fatty; those from SPE rats were consistently fatty. 

 Only two of the animals fed SPE diet had livers 

 with less than 30 percent fat. The highest per- 

 centage of fat observed was 63.3 percent in a liver 

 from a rat fed SPE diet. 



With the techniques used, fat was not detected 

 microscopically unless present in excess of 30 

 percent. When the concentration of fat was be- 

 tween 30 and 40 percent, numerous small vacuoles 

 were observed. When fat exceeded 40 percent, 

 large as well as small vacuoles were apparent. 



Although protein and ash in the livers from SPE 

 rats were diluted by fat, the total content of each 

 was equal to or greater than that found for these 

 components in the livers of stock or SP 8 HVO 

 rats. 



In table 57 are summarized data on the composi- 

 tion of livers from rats fed stock, SP 8 HVO, and 

 SPE diets as related to liver weight. There 

 appeared to be little evidence that the composition 



of this organ was influenced by its size. Livers 

 from stock rats were similar in composition 

 whether their average weight was 14.9 or 23.1 

 grams. The percentage of fat in livers weighing 

 less than 16 grams was low in comparison with 

 the larger livers from rats fed SPE diet. However, 

 small livers were rarely seen in rats fed this diet. 

 The increase in liver fat with age that was ob- 

 served in rats fed SP 8 HVO diet seemed to be 

 related, in part at least, to the body weight of 

 these animals. In table 58 are summarized the 

 results for liver fat as related to body weight. 

 For animals weighing less than 600 grams, the 

 increase in the average percentage of fat with age 

 was small and, considering the range of values 

 observed, was of questionable significance. The 

 percentage of fat in the livers of rats weighing 

 between 600 and 700 grams was significantly 

 higher (P < 0.01) than in the livers of the lighter 

 animals. Of the 11 rats weighing between 600 

 and 700 grams, 10 had livers containing more than 

 20 percent fat. In the larger rats weighing more 

 than 700 grams, there was some indication that 

 liver fat was lower when kidneys showed evidence 

 of damage. The 4 rats in this group with liver 

 fat less than 20 percent had kidneys showing de- 

 generative changes; the 2 rats with normal kidneys 



Table 57. — Protein, fat, and ash in livers of different weights from fasted and nonfasted rats fed stock, SP 



8 HVO, and SPE diets 



Condition, diet, and range 



Rats 



Average 



liver 

 weight 



Water 



Based on dry weight 



of liver weights (grams) 



Protein 



Fat 



Ash 



Nonfasted rats: 

 Stock: 



Less than 16.0 _ _ __ 



Number 

 4 

 5 

 5 



12 



10 



9 



2 



3 

 12 

 13 



Grams 

 14. 9 

 16. 6 



23. 1 



10. 7 



13. 



14. 6 

 18.0 



14. 1 

 18.2 



24. 1 



Percent 

 71. 

 71. 7 

 69.9 



67.9 

 68.4 

 67. 4 

 70. 2 



64. 6 

 60. 3 

 59. 



Percent 

 70.4 

 68. 

 69.4 



72.0 

 71. 6 

 68. 2 

 70.2 



64. 7 

 50. 9 

 48. 4 



Percent 

 15. 4 

 14.3 

 14. 8 



19. 

 18. 7 

 22 4 

 18! 



28.9 

 42. 6 

 45. 6 



Percent 

 4. 3 



16.0 to 19.9 . . 



4. 5 



20.0 and over- _ _ 



4. 7 



Fasted rats: 



SP 8 HVO: 



Less than 12.0 



12.0 to 13.9 



4. 6 

 4. 6 



14.0 to 15.9 



4. 6 



16.0 and over 



4.7 



SPE: 



Less than 16.0 



3.8 



16.0 to 19.9- 



3.3 



20.0 and over _ _ _ ______ 



3.3 







Table 58. — Liver fat and body weight of fasted rats maintaining weight on SP 8 HVO diet 



Body weight range (grams) 



Rats 



Average 



body 



weight 



Average 



liver 

 weight 



Liver fat on dry- 

 weight basis 





Average 



Range 



Less than 500.. - _______ 



Number 



6 



10 



11 



6 



Grams 

 462 

 550 

 653 



742 



Grams 

 10. 4 

 12.4 



13. 7 



14. 6 



Percent 



17. 1 



18. 

 22. 1 

 21.0 



Percent 

 14. 8-19. 1 



500 to 599 



15. 5-21. 7 



600to699__. _ .. 



19. 4-28. 6 



700 and over 



17. 8-28. 3 







70 



