Nutrition

Abstract

An attempt will be made in this review to emphasize those areas of in vestigation in which noteworthy progress has been made. One of the out standing difficulties encountered in assessing progress in nutrition during 1953 was the lack of standardization of diets used by laboratories when simi lar problems were under study. The gathering volume of data indicates the marked effect of small changes in the diet when the nutrient or the metabolic balance is critical. This is perhaps one of the most significant aspects of nu trition research with experimental animals during the past year. It is hearten ing that Turk (1), a leading soils authority, should "spike" the half-truths of the food faddist by stating, "The theory that the over-all nutritive value of foods for man is favorably influenced by a fertile soil has not been proved," which means that the qualitative character of foods is little affected by fer tilizers applied to the soil. CARBOHYDRATESRatio techniques for the estimation dry of matter consumption of grazing animals have been studied by Kane et at.(2). The method requires two fac tors: A measurable constituent present in the forage, such as lignin, plant pigment, or indigestible protein; and an indigestible substance such as chromium sesquioxide, barium sulfate, radioactive isotopes, or dyes. The following formulae were developed: per cent indicator in the feed (A) Dry matter digestibility = 10�100 . per cent indicator in the feces Total amount of "external" indicator fed (B) Dry matter consumption = --------------Amount of "external" indicator in feces multiplied by Amount of dry matter in feces sample Per cent dry matter indigestibilityThese authors have shown that the dry matter intake calculated by formula B, based upon chromium oxide and lignin, agreed closely with weighed amounts of dry matter fed to experimental animals and were equally valid with standard total collection procedures. This held for other internal factors as well as laboratory indicators. The results obtained were within plus or 1 The survey of the literature pertaining to this review was completed in Novem ber, 1953. t The following abbreviation is used: TDN for total digestible nutrients. 319 Annu. Rev. Biochem. 1954.23:319-344. Downloaded from www.annualreviews.org Access provided by Michigan State University Library on 02/07/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS