REPRODUCTIVE ENDOCRINOLOGY IN BIRDS 



1107 



did not show any carry-over effects (Eaton, 

 Carson and Beall, 1955). Whether or not 

 estrogen i)lays a role in the regulation of 

 some of the reproductive functions of males 

 cannot be stated definitely until evidence 

 of estrogen secretion during various i)arts 

 of the !'ci)i'()(hi('ti\'<' cycle has been o})tained. 



7. Xiitritiun 



'i'lie importance of various nutrients for 

 the normal development of the rei)roductive 

 tract is hardly in doubt. Unfortunately, as 

 Lutwak-lViann (1958j pointed out, few ex- 

 periments have been carried out on the 

 effects of nutritional deficiencies on repro- 

 duction of male birds, and in these the data 

 presented were not statistically analyzed 

 and do not lend themselves to such analy- 

 sis. The conclusions reported here, therefore, 

 may have to be accepted with reservations. 



The lack of statistical analysis leads to a 

 criticism of the design of some of the ex- 

 periments, in which it was impossible to 

 distinguish the effect of a specific de- 

 ficiency from general inanition. The latter 

 has been shown to be a cause of atrophy of 

 the testes (Portier, 1920; Parker and Mc- 

 Spadden, 1943; Mason, 1949; chapter by 

 Leathern ) . 



Some of the studies on the effect of nu- 

 trition on reproduction in male birds have 

 been directed to the problem of vitamin de- 

 ficiencies. Of the fat-soluble vitamins, only 

 A, D, and E have been studied in relation 

 to their influence on male reproductive per- 

 formance. Vitamin A deficiency leads to 

 atrophy of the testes of roosters although 

 body weight is not affected (Lowe, Morton, 

 Cunningham and Vernon, 1957). This effect, 

 therefore, is probably a specific deficiency 

 symptom rather than a symptom of inani- 

 tion. Feeding a vitamin A-deficient ration 

 to mature cockerels resulted in a sharp de- 

 crease in the number of spermatozoa per 

 ejaculate, whereas the incidence of morpho- 

 logically abnormal and of nonmotile sperm 

 increased. These symptoms all proved to be 

 reversible when vitamin A was fed (Paredes 

 and Garcia, 1959) . 



Vitamin E deficiency resulted in abnor- 

 mal spermatozoa (Adamstone and Card, 

 1935) and atrophy of the testes (Adamstone 

 and Card, 1934; Herrick, Eide and Snow, 



1952). This atrophy may have been the re- 

 sult of a decrease of gonadotrophin secretion 

 by the anterior pituitary (Herrick, Eide 

 and Snow, 1952). Unfortunately, no data 

 were given on body weights, so that it is 

 not certain whether or not the observed 

 effect was the result of starvation. In our 

 laboratory, vitamin E deficiency has often 

 resulted in a decrease in body weight, and 

 thus it seems possible that, in the experi- 

 ments cited, inanition may have been a 

 contributing factor in causing testicular 

 atrophy. 



Feeding of vitamin D-deficient diets from 

 6 weeks of age caused a decreased testicular 

 weight in cockerels 14 and 16 weeks of age. 

 (Buckner, Insko, Henry and Wachs, 1951). 

 Body weights of the vitamin-deficient birds 

 were less than half those of the controls, 

 thus indicating that inanition was a con- 

 tributing factor. 



Investigations of vitamin B deficiencies 

 have been carried out by Haque, Lillie, 

 Shaffner and Briggs (1949). Unfortunately, 

 no statistical analysis of the data was re- 

 ported nor do the published data lend them- 

 selves to analysis. An increase or decrease 

 in testicular weight even at 50 per cent may 

 not be significant, for under normal con- 

 ditions testicular weight shows great varia- 

 bility. A vitamin deficiency may increase 

 this variability even more, because some 

 birds may have a genetically lower re- 

 quirement than others. The latter statement 

 finds support in the observations by Howes 

 and Hutt (1952) and Laraoreux and Hutt 

 (1939, 1948) that breeds differ in their nu- 

 tritional requirements. On the basis of data 

 available in the literature and after careful 

 consideration of the possible effects of inani- 

 tion Mason (1939) concluded that thiamine 

 deficiency per se caused testicular dysfunc- 

 tion. 



Haque, Lillie, Shaffner and Briggs (1949) 

 determined the response of the comb to a 

 standard dose of androgen in birds fed 

 diets deficient in various vitamins. With the 

 reservation that statistical analysis might 

 prove them incorrect, the tentative con- 

 clusions may be drawn that deficiency of 

 vitamin E, nicotinic acid, or riboflavin re- 

 sults in a greater than normal response of 

 the comb. The explanation for this effect 



