VIII. MISCELLANEOUS FACTORS 593 



tion, as in guinea pigs, was alleviated by feeding oatmeal but was aggra- 

 \atcd b}' increasing ihe phosphate content of the diet. Vitamin E was 

 inetl'ective. INIicroscopic appearance of the tissue lesions'" was reported to 

 be similar to those in guinea pigs."^ 



The gross similarities in guinea pig stiffness and human arthritis confer 

 a continuing interest upon tliis unusual disease. It is hoped that studies will 

 be resumed which will aim at the development of sound analytical proce- 

 dures and the estabhshment of the nutritional antl metabolic relationships 

 that may exist. 



VIII. Miscellaneous Factors 



The recent literature contains many depositions describing factors for 

 growth, reproduction, and intermediary metabolism. The evidence is fa- 

 vorable that one or more of these will pro^'e to be of major importance. This 

 is particularly true in the field of poultry nutrition,'''^ ■ "•* where at least 

 ten reports of new factors have been issued. However, caution is urged in 

 accepting the entire group as bona fide factors, for most of them have not 

 yet been purified or sufficiently cross-checked against other factors to deter- 

 mine what aliases may exist. In addition to probable duplications, the newer 

 members of the B12 group (see Chapter 3) as well as antibiotics may be 

 responsible for some of these effects. Artifacts may be obtained owing to 

 interplay of known factors, e.g., amino acid and amino acid-vitamin im- 

 balances; such derived foods as processed soybean meals, which are used 

 in many poultry diets, may vary considerably in their composition. Finally, 

 the possibility exists that uncontrolled pathogenic organisms in the intesti- 

 nal tracts of animals may influence performance in a non-uniform manner, 

 particularly where mobiUty is restricted, as in poultry batteries. 



A list of several of these and other newly described factors is given in 

 Table I. Where possible, pertinent information is given regarding the sus- 

 pected identities which reflects the opinions of either the listed authors or 

 the present writer. Finally, for convenience in summarizing some of the 

 older hterature, several earher "vitamins" and related materials are listed 

 in Table II. These have either been discarded altogether or have been 

 shown to be replacable by one or more known compounds. It is unlikely 

 that these terms will ever be used again, for the growth factors of the future 

 ^^^ll probably be given names in keeping with their chemical structure or 

 biological function. 



Certain trends in future research on new growth factors may be adum- 

 brated by an analysis of the current Hst. Thus, factors for rat nutrition are 



"1 M. A. Constant, P. II. Phillips, and D. M. Angevine, J. Nulrilion 47, 327 (1952). 

 "2 P. N. Harris and R. Wulzen, Ain. J. Palhol. 26, .595 (1950). 



1" H. Menge, G. F. Combs, P.-T. Hsu, and M. S. Shorb, Poultnj Set. 31, 237 (1952). 

 1" H. Menge and G. F. Combs, Poultry Sci. 31, 994 (1952). 



