336 



ANIMAL BIOCHEMISTRY 



Daily riboflavin allowances for growing swine range from 2.1 mg. 

 (50 lb. live weight) to 6.3 mg. (250 lb. live weight). No allowances 

 have been recommended for breeding, pregnant, and lactating animals. 

 The tentative allowance for horses is 2 mg. per 100 lb. of body weight. 

 Since bacteria synthesize riboflavin in the rumen in quantity, rumi- 

 nants do not need a dietary source of this vitamin. 



Inasmuch as riboflavin is a factor in many metabolic processes, it 

 occurs in all metabolically active plant and animal tissues. The best 

 dietary sources are yeast, liver, kidney, milk, eggs, fish, oysters, and 

 muscle tissues. Alfalfa meals are relatively good and cereal grains 

 are fair but not rich sources. Fermentation residues from alcohol 

 manufacture probably offer the richest large supplies. 



Deficiency 



Lack of riboflavin leads to bloodshot eyes, a typical dermatitis, and 

 loss of hair as early symptoms in human beings and animals. Human 

 beings later develop facial lesions, especially of the lips, and cracks 



FIGURE 14-2. El[ects of the absence and the presence of riboflavin in the ration of 

 turkey poiiUs. Note retarded growth and prostrated condition (leg paralysis and 

 curled toes) of the poult which received the ribonavin-deficient ration in contrast to 

 the poujt which received the same ration supplemented with crystalline riboflavin. 



(Courtesy of Dr. R. V. Boucher.) 



