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Departments of Poultry Husbandry and Biochemistry and Nutrition, Texas Agricultural Experiment Station, College Station
The growth of New Hampshire chicks was increased by feeding an APF concentrate or by injecting crystalline vitamin B12. The vitamin B12 content of the tissues has been shown to be related to the feeding of APF concentrates or to the injection of the crystalline vitamin, or both. The alfalfa sample used in this test depressed the growth of the birds and tended to decrease the vitamin B12 content of the tissues when groups fed equivalent levels of APF were compared. Such growth inhibition could not be overcome by feeding an excess of vitamin B12 in the form of an APF concentrate. APF concentrate 4 produced an increase in growth over that obtained by injecting crystalline B12, and such an increase is thought to be due to the aureomycin contained in this concentrate. However, the B12 content of the liver and kidney from birds fed APF 4 was not as high as that of those from chicks injected with 1 µg B12 per chick per week.
2 The crystalline vitamin B12 used in the microbiological assays was generously supplied by Dr. D. F. Green, Veterinary Department, Merck and Company, Rahway, New Jersey.
3 A preliminary report of this work was presented before the annual meeting of the American Institute of Nutrition, Atlantic City, New Jersey, April 19, 1950.
Manuscript received 13 June 1950.