Rats maintaining weight on SPM, SPB, and 

 SPPB diets. — The limited data for rats fed diets 

 containing high levels of milk, beef, or peanut 

 butter are reported in table 65. The results for 

 rats fed SPM and SPB diets were similar to those 

 for SP 8 HVO rats. In general, serum cholesterol 

 levels were low in rats under 400 days of age, and 

 tended to be higher in rats 400 to 599 days of age. 

 The slightly higher value for rats under 400 days 

 of age on SPPB diet was due to inclusion of one 

 rat with a value of 236 mg./lOO ml., and is of 

 questionable significance considering the limited 

 data available. In the older rats fed this diet, 

 however, cholesterol values were significantly 

 higher (P<0.01) than those for rats of comparable 

 age fed stock, SP 8 HVO, SPM, or SPB diets, 

 with 54 percent exceeding 200 mg./lOO ml. 



Rats losing weight on stock, SP 8 HVO, 

 SPE, SPM, SPB, and SPPB diets.— In table 66 

 are summarized similar data for rats that were 

 losing weight on these same diets. The results 

 are reported without regard to weight loss before 

 sacrifice. Although there seemed to be a trend 

 toward somewhat higher cholesterol values when 

 weight loss exceeded 100 grams, the data available 

 were too few to warrant separation on this basis. 

 Differences in serum cholesterol with age and with 

 diet were still apparent in the moribund rats. 

 Cholesterol levels exceeding 150 mg./lOO ml. were 

 rarely seen in rats less than 400 days old on SP 



8 HVO, SPM, and SPB diets. In the intermedi- 

 ate age group, elevated cholesterol values were 

 found with all diets, although the proportion of 

 rats with high serum levels and the extent of the 

 elevation depended upon the dietary regimen of 

 the rats. Except with SPPB diet, rats with a 

 relatively long lifespan tended to have lower 

 cholesterol levels than did those in the intermedi- 

 ate age group. Rats fed stock or SP 8 HVO diets 

 generally had lower levels than did those fed the 

 other diets. One exceedingly high value of 1,813 

 mg./lOO ml. has been omitted from the average 

 value recorded for stock rats. In this animal the 

 thyroid gland was almost entirely replaced by 

 tumor. On SPE and SPPB diets, the proportion 

 of elevated cholesterol values was high in compari- 

 son with those obtained in rats fed the other diets 

 investigated. 



Cholesterol and kidney damage. — -The in- 

 crease in serum cholesterol with age appeared to 

 be associated, in part at least, with an increase 

 in the number of rats with enlarged and damaged 

 kidneys. In table 67 are summarized data relat- 

 ing kidney size to serum cholesterol level. On 

 stock, SP 8 HVO, SPM, or SPB diets, levels 

 exceeding 150 mg./lOO ml. were rarely found in 

 healthy or moribund rats with kidneys weighing 

 less than 1.8 grams. Kidneys in this weight 

 range showed little evidence of degenerative change. 

 Somewhat higher serum cholesterol levels tended 



Table 66. — Influence of diet and age on serum cholesterol levels in rats losing weight on stock, SP 8 HVO, 



SPE, SPM, SPB, and SPPB diets 





Rats 



Average 

 age 



Serum cholesterol 



Diet and age of rats 

 (days) 



Average 



Range 



Rats with cholesterol levels of — 





Less than 

 150 mg./ 

 100 ml. 



150 to 199 



mg./lOO 

 ml. 



200 to 299 



mg./lOO 



ml. 



300 mg./ 

 100 ml. 

 and over 



Stock : 



500 and over 



SP 8 HVO: 



Less than 400 . 



400 to 699. ._ 



Number 



9 



5 



12 



3 



7 

 16 

 40 

 12 



4 

 5 

 1 



3 

 3 

 5 



12 

 10 



2 



Days 



721 



264 

 570 

 743 



189 

 367 

 497 

 640 



340 

 501 

 600 



268 

 535 

 704 



306 

 520 

 663 



Mg./lOO ml. 



166 



91 

 182 

 113 



153 

 386 

 346 

 218 



184 

 258 

 175 



118 

 348 

 162 



163 

 276 

 315 



Mg./lOO ml. 



101-235 



80-103 

 84-385 

 96-129 



90-248 

 121-904 

 132-932 

 115-290 



103-419 



122-573 



175 



98-134 

 155-620 

 105-220 



51-298 

 138-654 

 289, 341 



56 



100 



42 



100 



57 

 6 

 5 



17 



75 



20 







100 







40 



67 



30 







22 





 33 









 6 

 2 

 







20 



100 





 33 



20 



8 



10 







22 





 8 

 



43 

 19 

 35 



83 







40 









 33 



40 



25 



30 















17 



700 and over . 

 SPE: 



Less than 300 



300 to 399 









 69 



400 to 599 . 



58 



600 to 699. .. . 







SPM: 



Less than 400 . __ 

 400 to 599 



25 

 20 



600 and over. . 

 SPB: 



Less than 400.. 

 400 to 599 









 33 



600 and over . 

 SPPB: 



Less than 400 



400 to 599 .. . . 









 30 



600 and over 



100 



79 



