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Department of Animal Husbandry, Cornell University, Ithaca, N. Y.
ABSTRACT
Conclusions: The knowledge of nutrition has expanded greatly during this semicentennial period. All of the known vitamins were discovered and the degree of their essentiality for dairy cattle was largely determined. The essentiality of magnesium, iron, copper, and cobalt was discovered, and important contributions were made to the already existing knowledge that calcium, phosphorus, iodine, sodium, potassium, and sulfur perform essential functions in the animal body. In addition, the toxic effects of substances such as fluorine, selenium, molybdenum, nitrates, and dicumarol occurring naturally in feedstuffs were discovered and, in some cases, means of prevention and/or cure were worked out. It developed that some of the mineral deficiencies and excesses prevailed in certain areas, implicating soil structure, climate, and fertilization and management treatments. Although an excellent foundation knowledge of the use of dietary energy by cattle had accumulated by the end of the nineteenth century, the greater part of the present knowledge derived from studies conducted during the first three decades of the present semicentennial period. Detailed studies were made of the biochemical, physiological, and pathological effects of dietary deficiencies, excesses, and interrelationships. The knowledge that the dairy cow by virtue of her rumen can digest crude feeds and synthesize many metabolically essential substances has largely developed during the last 50 years. The information thus accrued has been employed to determine the nutrient requirements of cattle for various body functions. Improvements in chemical methods used before 1906 and the introduction of new chemical, physical, and biological methods since 1906 have made it possible to describe more completely the nutritive qualities of feedstuffs, factors affecting these qualities, and the effects of the feedstuff upon the animal. Information resulting from these developments has been used during this period in conjunction with the knowledge obtained on the nutrient needs in the formulation of feeding standards and, therefore, in the practical rationing of dairy cattle. Although by 1956 there is much need to reinvestigate the needs of dairy cattle for certain nutrients, particularly in relation to nutrients discovered since some of the requirements were quantitated, present-day feeding standards in conjunction with economic values provide for the feeding of dairy cattle on a more satisfactory, scientific and economic basis than ever before. Many problems seeming to implicate nutrition and feeding remain in 1956, however. An attempt has been made here to sketch the historical development of only a few significant occurrences in the nutrition and feeding of dairy cattle; the reader will recognize many gaps, as complete coverage has not been attempted.
1 Guggenheim Fellow, 1955–56, at National Institute for Research in Dairying, University of Beading, England.
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