Section G. General. Nitrogen metabolism and the rumen

Abstract

The fact that rumen micro-organisms have a modifying effect on the utilization of food nitrogen by ruminants has been recognized for very many years (references to early work are given in Hungate, 1966) but until about 1947, when this subject was reviewed by McNaught & Smith (1947), many of the processes involved were not well understood. Since that time a large amount of work has been done in this field and more recent reviews (Chalmers & Synge, 1954; Blackburn, 1965; Hungate, 1966; Waldo, 1968) present a much clearer picture. Most of the work covered by these authors will be mentioned only briefly in the present review and attention will be directed mainly to developments reported in the last few years. Few references to work published before about 1964 will be given as they may readily be found in later publications.

Voltage Dependence of Junctional Conductance in Early Amphibian Embryos

“…Records similar to those in Fig. 1 have been obtained from pairs of Limulus retinula cells, but the morphological basis is unclear and the mechanism may be quite distinct (2,12).…”

A Rapid Procedure for Purine Measurement and Its Use for Estimating Net Ruminal Protein Synthesis

“…Combining this purification procedure with the hydrolysis procedure of Marshak and Vogel (1951) In that trial, acid-precipitated casein was included as one source of N. As some of this insolubilized casein escaped ruminal digestion in a subsequent study (Zinn and Owens 1983) Storm et al (1983) by Savage (19'77), 697o by Santos et ai. (1982), 69-1l%o by Merchen and Satter (1983), 6l-7O7o by Hvelplund (1984),70-137o by Moller et al (1984) (Ling and Buttery 1978;Siddons et al 1982 (Smith 1969(Smith , 1975Czerkawski 1976), though Ling and Buttery (1978) (Siddons et al 1982) but should not alter purine content (Ha and Kennelly 1984). In addition, backflow of digesta into the duodenum following intestinal hydrolysis of polynucleotides but before absorption of nucleic acids from the small intestine should not alter purine recovery if any backflow of digesta is accompanied by the digesta marker.…”

Proteins in the digesta of the pig : amino acid composition of endogenous, bacterial and fecal fractions

“…Various other methods employing such markers as diaminopimelic acid (Synge, 1953) or nucleic acids (Smith, 1969) (Darcy, Laplace and Duée, 1982). The diaminopimelic acid (DAPA) content of all samples was assayed systematically using hydrolysates prepared according to the performic oxidation required for sulphur amino acid assay.…”