NUTRITIONAL EFFECTS 



685 



acids, for a deficiency or an excess can cre- 

 ate an imbalance and alter appetite. Oppor- 

 tunity to study the amino acids in reproduc- 

 tion is now possible because of the work of 

 Greenstein, Birnbaum, Winitz and Otey 

 (1957) and Schultze (1956) , who maintained 

 rats for two or more generations on syn- 

 thetic diets containing amino acids as the 

 only source of protein. Similarly, the amino 

 acid needs for egg-laying in hens has been 

 reported (Fisher, 1957). Tissue culture 

 methods also permit the study of the nu- 

 tritional requirements of embryonic gonadal 

 tissue, the success of avian gonadal tissue in 

 culture being judged by survival, growth, 

 and differentiation. In experiments in which 

 this technique was used it was found that a 

 medium made up of amino acids as the basic 

 nitrogen source can maintain gonadal ex- 

 plants very successfully, even though the 

 choice of amino acids does not exactly cor- 

 respond to the 10 essential amino acids rec- 

 ommended for postnatal growth (Stenger- 

 Haffen and Wolff, 1957). 



3. Carbohydrate 



The absence of dietary carbohydrate does 

 not appreciably affect the regularity of 

 estrous cycles in rats provided the caloric 

 need is met. However, the substitution of 

 20 per cent sucrose for corn starch induced 

 precocious sexual maturity which was fol- 

 lowed by sterility (Whitnah and Bogart, 

 1956). The ovaries contained corpora lutea, 

 but the excessive luteinization of unruptured 

 follicles suggested a hypophyseal disturb- 

 ance. Substitution of 20 per cent lactose for 

 corn starch had no effect. Increased amounts 

 of lactose retarded the gain in body weight 

 and blocked ovarian maturation, possibly 

 because the animal could not hydrolyze ade- 

 quate amounts of the disaccharide. Ad- 

 dition of whole liver powder to the diet 

 counteracted the depressing action of 45 per 

 cent lactose on the ovary (Ershoff, 1949). 



4. Fat 



There seems to be little doubt that dietary 

 fat is reciuired for normal cyclic activity, 

 successful pregnancy, and lactation, and 

 that the requirements for essential fatty 

 acids are lower in females than in males 

 (Deuel, 1956). 



Conception, fetal development, and par- 



turition can take place in animals fed a 

 diet deficient in fatty acids (Deuel, Martin 

 and Alfin-Slater, 1954) , despite a reduction 

 in total carcass arachidonic acid (Kum- 

 merow. Pan and Hickman, 1952). Earlier 

 reports indicated that a deficiency of es- 

 sential fatty acids caused irregular ovula- 

 tion and impaired reproduction (Burr and 

 Burr, 1930; Maeder, 1937). The large pale 

 ovaries lead Sherman (1941) to relate es- 

 sential fatty acid deficiency to carotene 

 metabolism. In this regard the removal of 

 essential fatty acids from an adequate diet 

 supplemented with vitamin A and E lead 

 to anestrum and sterility while maintaining 

 good health (Ferrando, Jacques, Mabboux 

 and Prieur, 1955). Perhaps the differences 

 in opinion regarding the effects of fatty acid 

 deficiency can be related to the duration of 

 the experimental period. Panos and Finerty 

 (1953) found that growing rats placed on 

 a fat-free diet exhibited a normal time for 

 vaginal opening, normal ovarian weight, 

 follicles, and corpora lutea, although in- 

 terstitial cells were atrophic. However, reg- 

 ular estrous cycles were noted for only 20 

 weeks, thereafter 60 per cent of the animals 

 exhibited irregular cycles. 



A decrease in reproductive function may 

 be invoked by adding 14 per cent arachis 

 oil to the diet (Aaes-Jorgensen, Funch and 

 Dam, 1956) . Increasing dietary fat by add- 

 ing rape oil did not influence ovarian func- 

 tion but did cause the accumulation of 

 ovarian and adrenal cholesterol (Carroll 

 and Noble, 1952). 



Essential fatty acid deficiency is as- 

 sociated with underdevelopment and 

 atrophic changes of the uterine mucosa. 

 Adding fat to a stock diet enhanced uterine 

 weight in young animals at a more rapid 

 pace than body weight (Umberger and 

 Gass, 1958) . 



5. Vitamins 



Carotenoid pigments are present in the 

 gonads of many vertebrates and marine in- 

 vertebrates, and, in mammals, are par- 

 ticularly prominent in the corpus luteum. 

 However, no progress has been made in 

 determining either the importance of the 

 carotenoids in the ovary or of the factors 

 controlling their concentrations. It is well 

 known that vitamin A deficiency induces 



