170 vitamins a and carotenes 



11. Turkeys 



Studies on the vitamin A requirement of turkeys have been limited 

 mainly to poults. The results of several of these studies are summarized 

 in Table XXI. The NRC subcommittee recommendation, 4000 I.U. per 

 pound of feed, applies to both poults and breeders and is therefore in excess 

 of what is required for growth. A level of 2500 I.U. per pound of feed should 

 be adequate for growth. 



12. Insects 



A few species of insects are the only invertebrates that have been studied 

 specifically as to their vitamin A requirements. None of the insects studied 



TABLE XXI 

 Estimates of the Vitamin A Requirements of Turkey Poults 



(the cockroach, Blatella germanica,^^ the clothes moth, Tineola hisselliella,^^ 

 the flour beetle, Tribolium confusum^'^) were shown to require vitamin A 

 or carotene. In the cockroach the body lipids were shown to be free of vi- 

 tamin A.^" The failure to demonstrate a need for vitamin A by these species 

 and the frequent use of media that are essentially free of vitamin A and 

 carotene for raising invertebrates probably indicates that they do not re- 

 quire vitamin A. 



^s W. C. Russell, M. W. Taylor, and R. Van Reen, Federation Proc. 8, 394 (1949). 

 " R. Van Reen, M. W. Taylor, and W. C. Russell, J. Nutrition 43, 235 (1951). 

 " H. M. Scott, Kansas Agr. Expt. Sta. Bull. 276, (1937). 

 « H. S. Wilgus, Colo. Farm. Bull: 2, 3 (1940). 



49 F. D. Wharton, L. D. Matterson, H. M. Scott, and C. I. Bliss, J. Nutrition 39, 543 

 (1949). 



60 R. E. Bowers and C. M. McCay, Science 92, 291 (1940). 



61 M. F. Crowell and C. M. McCay, Physiol. Zool. 10, 368 (1937). 



62 M. D. Sweetman and L. S. Palmer, ./. Biol. Chcm. 77, 33 (1928). 



