822 XIII. ESSENTIAL FATTY ACIDS 



did observe improved lactation performance in the case of rats on diets 

 containing corn oil, as compared with animals on a fat-free diet or on one 

 containing hydrogenated coconut oil, which might be interpreted as related 

 to an intake of EFA. However, no improvement in lactation was noted 

 when as much as 125 mg. of linoleate was given per day to the mother or 

 directly to the pups. In the most recent studies of Deuel et o/.,-"'* 100% 

 mortality was observed before weaning when the fat-free diet of the mothers 

 was supplemented with 10 mg. of cottonseed oil or with 10 mg. of linoleate. 

 However, the lowest mortality rate and the highest weaning weights of the 

 pups were noted in rats receiving 100 or 200 mg. of cottonseed oil daily, or 

 80 mg. of linoleate. On this basis, the latter workers ascribe the beneficial 

 effect of fat upon reproduction and also upon lactation to the EFA present 

 in this foodstuff. 



(4) Protection against X-Irradiation 



Cheng and her co-workers'^" reported that cottonseed oil in amounts as 

 loAv as 2% in the diet of male rats affords protection against multiple sub- 

 lethal doses of x-ray, as compared with the situation noted in rats on a fat- 

 free diet. Decker et al.^^^ had observed earlier that a typical EFA defi- 

 ciency could be provoked in fat-depleted mice when they were exposed to 

 .\-irradiation. Although cottonseed oil had a protective effect against x-ir- 

 radiation in the experiments of Cheng et al.,^*^ irrespective of whether old 

 rats or young mature male animals were employed in the tests, it was found 

 that fat protected only the old female rats against x-irradiation. It was 

 suggested that, because of the higher linoleate requirement of the male ani- 

 mals, they Avere depleted of EFA sooner on the fat-free diet than were the 

 female rats. Consequently, the EFA level was not the limiting factor in 

 the protection of young rats. This hypothesis was supported by the longer 

 survival of the control females than of the control males in the group of 

 young mature animals. In another study, it Avas found that the linoleate 

 protection was in addition to that afforded by liver powder; moreover, 

 Cheng and Deuel -"^ proved that hydrogenated coconut oil gave no protec- 

 tion. 



In subsequent studies by Deuel, Cheng et al.,-^^ it was demonstrated that 

 the protective effect of cottonseed oil was a function of the EFA present 

 therein. Thus, when 10 mg. of ethyl linoleate were given daily to fat- 

 depleted rats which were subsequently exposed to weekly doses of x-rays 



209 A. L. S. Cheng and H. J. Deuel, Jr., Federation Proc, 12, 410-411 (1953). 



210 H. J. Deuel, Jr., A. L. S. Cheng, G. D. Kryder, and M. E. Bingemann, Science, 117, 

 254-255(1953). 



