848 XIV. NUTRITIONAL VALUE OF FATS 



interval during winch diets containing several fat levels were given ad 

 libitum. As soon as recovery occurred, breeding tests were carried out. 

 The following percentage of fertility was noted in the groups on various 

 diets: 0% fat, 20%; 5% fat, 0%; 10% fat, 20%; 20%o fat, 80%; and 

 40% fat, 80%. In no case were the mothers on a fat-free diet able to 

 raise their progeny through the age of twenty-one days. 



French, Ingram, Ivnoebel, and Swift'^ concluded, as a result of tests on 

 reproduction over three generations of albino rats fed diets ad libitum 

 composed of natural foods which varied in fat and carbohydrate content, 

 that there was a significant decrease in the reproductive performance of 

 the rats when 23% of fat was fed, as compared mth that noted when the 

 animals received a diet containing 4.4% fat, or one high in carbohydrate 

 (3.4% fat). However, a larger number of litters was produced by mothers 

 on the high-fat diet, and the total number of young was also considerably 

 greater, although the number per litter was less. Thus, on the control 

 diet the average number of surviving young was 10.0 ± 0.44, while on the 

 carbohydrate diet the average was 10.2 ± 0.37, as compared with a value 

 of 9.3 ± 0.32 for litters produced by mothers on the high-fat regimen. 

 The average birth weight of the rats was slightly lower in the high-fat 

 group, i.e. 6.1 ± 0.08 for the males, as contrasted mth 6.5 ± 0.08 and 

 6.4 ± 0.07 for the males receiving the low-fat and carbohydrate diets, 

 respectively, and 5.7 ± 0.07 for the females in the high-fat group as con- 

 trasted with 6.0 ± 0.07 for those whose mothers were on the other two 

 diets. The fact which was particularly striking was the increased number 

 of successful litters obtained on the high-fat diet in the third generation as 

 contrasted with the first. Thus, the number of litters was increased from 

 twenty-one to forty-three for the animals in the high-fat group, while the 

 values for the high-carbohydrate group increased only from twenty-one 

 to thirty, and for the control group from fifteen to twenty-two successful 

 litters. 



On the basis of these results it appears to the author that one might still 

 ascribe certain nutritional benefits to high-fat diets as contrasted with 

 low-fat diets, if one considers the number of successful pregnancies as the 

 dominant factor, rather than the weight of the newborn rats. Most of 

 the experimental evidence indicates the great importance of fat in rendering 

 normal pregnancy and lactation possible. To what extent this favorable 



^ C. E. Froiich, R. H. Ingram, L. K. Knoebel, and R. W. Swift, ./. Nutrition, 48, 91- 

 102(1952). 



