damage increased, liver fat tended to decrease and 

 often was too small to be apparent microscopically 

 without special stains for fat. 



Rats maintaining weight on SPM, SPB, 

 and SPPB diets. — In table 29 are summarized 

 data for the weights of the livers and kidneys 

 from fasted and nonfasted rats that were main- 

 taining their weight on diets containing milk, 

 beef, or peanut butter. For comparison, data are 

 also included for rats fed SP 8 HVO and SPE 

 diets from the same experimental series. The 

 younger fasted or nonfasted rats were littermates 

 except for an occasional death before the age 

 scheduled for sacrifice. 



The influence of fasting on the size of the kidney 

 as well as the liver was again apparent in the 

 results for the young rats. In general, the 

 results for SPM, SPB, and SPPB diets were 

 similar to those obtained with the semipurified 

 diet except for the tendency to large livers in 

 animals over 400 days old fed SPPB diet. For 

 aU diets except the SPE diet, an increase in liver 

 weight with age was accompanied by a parallel 

 increase in body weight, with the liver remaining 

 a relatively constant percentage of the body 

 weight. The tendency for certain litters to be 

 particularly prone to enlarged, damaged kidneys 

 was apparent in the group of rats 400 to 600 days 

 of age. One litter accounted for the largest 

 kidney recorded in table 29 for each of the diets 

 except SPE. The littermate fed SPE diet was 

 moribund at the time of sacrifice and had a kidney 

 weighing 8.7 grams. The kidney weighing 5.57 

 grams from the littermate fed SPB diet was 



responsible for the high average ratio of kidney to 

 body weight noted for this diet. 



Rats losing weight on SPM, SPB, and SPPB 

 diets. — -Differences among these diets became 

 apparent in rats that were losing weight, as is seen 

 in table 30. Some extremely large kidneys were 

 found in young rats fed SPPB diet, particularly 

 in the nonfasted animals. The largest kidney 

 observed, weighing 15.8 grams, was from a 341- 

 day-old nonfasted rat fed this diet. Although 

 large kidneys were a frequent finding in SPPB 

 rats, the kidneys of a small group of older non- 

 fasted rats that had lost less than 100 grams were 

 normal in size. This group of animals included 

 the oldest surviving rats on this diet. Enlarged 

 kidneys were a frequent finding when weight loss 

 exceeded 100 grams, regardless of diet, although 

 there were relatively few large kidneys among the 

 older SPM rats. The relation of kidney size to 

 the extent and type of damage observed was 

 similar to that previously discussed for rats fed 

 SP 8 HVO or SPE diets; hyalin casts were gen- 

 erally present in kidneys weighing 2 grams or more 

 and cystic and glomerular damage in those exceed- 

 ing 3 grams in weight. 



The livers from SPPB-f ed rats tended to be large 

 but were generally smaller than those from SPE- 

 fed rats. In contrast to the results with SPE 

 diet, the large livers from rats fed SPPB diet 

 generally showed little microscopic evidence of fat. 



Rats fed SPE diet with added nutrients. — 

 In table 31 are summarized data for the kidney 

 and liver weights of rats fed the 10 supplemented 

 SPE diets. Enlarged kidneys and livers such as 



Table 29. — Kidney and liver weights of fasted and nonfasted rats maintaining weight at different ages on 



diets with protein-fat-containing foods 



Condition, age of rats 



Rats 



Aver- 

 age 

 age 



Kidney weight 



Liver weight 



Aver- 

 age 

 body 



weight 



Kidney 



to 



body 



weight 



Liver 



to 



body 



weight 



Liver 



to 



(days), and diet 



Average 



Range 



Average 



Range 



kidney 

 weight 



Fasted rats 



200 to 399 days: 



SP8 HVO 



Number 

 5 

 5 

 6 

 6 

 6 



10 

 6 



7 

 8 

 8 



10 

 10 

 10 

 10 

 10 



Days 

 313 

 313 

 304 

 304 

 289 



523 

 496 

 503 

 502 

 509 



201 

 201 

 202 

 202 

 202 



Grams 

 1.37 

 2. 09 

 1. 38 

 1. 52 



1. 43 



2. 01 



2. 09 

 1.90 

 2. 16 

 2.06 



2. 08 

 2. 04 

 1. 98 

 1. 90 

 1. 96 



Grams 

 1. 23-1. 60 

 1. 60-2. 91 

 1. 06-1. 85 

 1. 16-2. 23 

 1. 12-1. 91 



1. 43-2. 59 

 1. 55-3. 82 

 1. 43-3. 20 

 1. 33-5. 57 

 1. 46-3. 68 



1. 43-3. 32 

 1. 76-2. 22 

 1. 51-2. 34 

 1. 55-2. 24 

 1. 59-2. 85 



Grams 



10. 7 

 21. 7 



11. 9 

 11. 9 

 11. 8 



14 6 



18.9 

 13. 8 

 13. 8 

 16. 9 



21. 6 

 23. 9 

 21. 2 

 18. 6 

 20. 



Grams 



9. 1-13. 1 



17. 0-30. 1 



7. 3-16. 2 



8. 7-15. 5 



10. 4-14. 3 



11. 9-18. 2 

 14. 3-24. 4 

 10. 4-19. 6 



9. 4-18. 8 



13. 0-22. 5 



14. 3-30. 7 

 19. 2-27. 1 

 16. 5-27. 5 

 16. 5-21. 9 



15. 0-27. 7 



Grams 

 523 

 578 

 580 

 540 

 495 



716 

 648 

 659 

 642 

 741 



530 

 540 

 581 

 540 

 569 



Percent 



0. 27 



. 36 



. 24 

 . 28 

 . 29 



. 28 

 . 32 

 . 29 

 . 34 

 . 28 



. 39 

 . 37 

 . 34 

 . 35 

 . 34 



Percent 



2. 1 



3. 7 

 2. 

 2 ^ 

 2. 4 



2. 

 2. 9 

 2. 1 

 2. 1 

 2. 3 



4. 1 

 4. 4 

 3.7 

 3.4 

 3.5 



Ratio 



7. 8 



SPE 



SPM 



10. 6 



8. 6 



SPB 



7. 8 



SPPB_ 



8 6 



400 to 499 days: 



SP 8 HVO 



7. 4 



SPE 



9. 9 



SPM 



7. 3 



SPB 



6 6 



SPPB 



8. 5 



Nonfasted rats 



150 to 250 days: 



SP 8 HVO 



10 5 



SPE 



11 8 



SPM 



10 7 



SPB___ 



9. 8 



SPPB 



10 3 







45 



