2 To find the effects produced when pigeons are fed diets lacking thiamin 

 (vitamin B), feed one young pigeon brown rice and water and another white rice 

 and water — that is, a diet lacking thiamin. Keep a daily record and graph of the 

 food consumed and of the weight of each pigeon. Should the growth curve of the 

 pigeon on white rice drop sharply, give close attention to the animal, as poly- 

 neuritis and death will result if the animal is kept on this diet too long. The 

 pigeon may be saved, even after polyneuritis develops, if it is promptly given 

 thiamin. What effect does a lack of thiamin have upon the appetite? What 

 abnormal effects does a lack of thiamin produce? 



3 To find the effect of a diet deficient in ascorbic acid feed one of two guinea- 

 pigs, weighing approximately 300 g each, a complete diet and the other a diet 

 lacking ascorbic acid.^ 



Keep a record of weights and make a graph showing the growth curve of each 

 animal. Compare results in weight and appearance and note conclusions. 



4 To find the effects of vitamin A and thiamin deficiencies, keep three pairs 

 of rats on diets having vitamin differences. Keep one pair of rats, from three to 

 four weeks old, on a complete diet; one pair on a similar diet lacking vitamin A; 

 and the third pair on a similar diet lacking thiamin. All the conditions for the 

 three pairs should be exactly the same, except for the variations in the diet.^ 

 Weigh weekly for six weeks and plot the growth curve of the rats on each diet. 

 Compare results and note conclusions. 



^This diet consists of a mixture of rolled oats and bran, equal parts by volume, 50 g; 

 skim-milk powder (heat for 4 hr at 110° C), 30 g; butter, 10 g; and table salt, 1 g. For the 

 normal, or control, diet use the same combinadon but add 10 g or more of spinach or other 

 greens, or 1 mg of pure ascorbic acid (vitamin C) daily. Prepared rabbit foods on the market 

 are complete in every essential but ascorbic acid, and may be substituted for the mixture 

 given above in performing this experiment. 



^Formulas for rat diet: 



Note that hydrogenation of oils results in solid fats. Hydrogenated cottonseed oil is 

 commonly used as shortening in place of lard and other solid fats. 



A good salt mixture to use contains in each 100 g: 5g NaCl, 16 g MgSO^ 7 H.O, 10 g 

 NaH.PO^Hp, 28 g K.HPO^, 38 g calcium lactate, 3 g iron lactate. 



Note that the thiamin-deficient diet (Diet II) is the same as the complete diet except 

 that the protein is vitamin-free and the yeast is autoclaved (that is, heated at 110° C for 

 4 hr) to destroy the thiamin. 



Note that the vitamin-A-deficient diet (Diet III) is the same as the complete diet except 

 that the protein is vitamjn-free and the cod-liver oil (source of vitamin A) is omitted. 



112 



