Nitrogen faecal

The procedure of sample preparation for faecal BA analysis and derivatisation is an adaptation of the method of Czubayko et al. [17]. The internal standard (125 pg HDCA) is added to the aqueous phase of extraction. The sample is saponified with 200 pi 10 mol/1 sodium hydroxide at 120°C for 120 min and then acidified to pH 1 with hydrochloric acid. After extraction of BAs with diethyl ether (4 x 1 ml), the solvent phases are pooled and evaporated under a stream of nitrogen. The residue is... 

Morales, C. E. (1987). Carbon and nitrogen content of copepod faecal pellets Effect of food concentration and feeding behavior. Mar. Ecol. Prog. Ser. 36, 107—114. 

Several other long-term effects of acarbose were explored in healthy men by Couet et al. (1988). There was an increase in faecal nitrogen excretion, while nitrogen balance decreased. Acarbose also increased the faecal excretion of starch, fat, iron and chromium. Plasma vitamin A decreased following acarbose treatment, while vitamin B6 increased. 

A. Picarelli, M. Greco, F. Di Giovambattista, A. Ramazzotti, C. Cedrone, E. Coarzziari, and A. Torsoli. Quantitative determination of faecal fat, nitrogen and water by means of a spectrophotometric technique near infrared reflectance analysis (NIRA). Assessment of its accuracy and reproducibility compared with chemical methods. Clin. Chim. Acta 234 147 (1995). 

Nitrites formed by nitrification from ammonia nitrogen also have a high indicator value they too are considerably adsorbed in soil. However, the source of their occurrence is not limited to faecal contamination. 

The values for faecal nitrogen digestibility (or crude protein digestibility) are given for all the species. In the case of rabbits and fish, these data are, in these tables, the only estimates of the nitrogen values of feed materials. 

Moughan PJ, Stevens EVJ, Reisma ID, Rendel ]. The effect of avopatcin on (be ileal and faecal digestibility of nitrogen and amino acids in the milk-fed calf. Animal Prod 1989 49 63-71. 

For poultry, the determination of digestibility is complicated by the fact that faeces and urine are voided from a single orifice, the cloaca. The compounds present in urine are mainly nitrogenous, and faeces and urine can be separated chemicaUy if the nitrogenous compounds of urine can be separated from those of faeces. The separation is based on the fact either that most urine nitrogen is in the form of inic acid, or that most faecal nitrogen is present as true protein. It is also possible to alter the fowl s anatomy by surgery so that faeces and mine are voided separately. 

This is a direct measure of the proportion of the food protein that can be utilised by the animal for synthesising body tissues and compounds, and may be defined as the proportion of the absorbed nitrogen that is retained by the body. A balance trial is conducted in which nitrogen intake and urinary and faecal excretions of nitrogen are measured, along with the endogenous fractions in these two materials. The biological value is then calculated as follows ... 

The endogenous urinary nitrogen results from irreversible reactions involved in the breakdown and replacement of various protein secretions and structures within the body. Thus, both the faecal and urinary endogenous fractions represent nitrogen that has been absorbed and utilised by the animal rather than nitrogen that cannot be so utilised. Their exclusion from the faecal and urinary values in the above formula gives a measure of the true biological value. 

Biological value is stated as the proportion of the nitrogen intake that is actually retained and takes account of endogenous urinary and faecal nitrogen, whereas chemical score and the essential amino acid index are based on the proportion of the main limiting amino acid of the protein in relation to that in a standard protein. 

Protein requirements for maintenance are estimated from endogenous urinary nitrogen and metabolic faecal nitrogen excretion. There are also small losses of nitrogen in hair and scurf. In ruminants the protein requirement for maintenance can generally be met by microbial protein synthesis. 

The net requirement for nitrogen for maintenance is that required to replace the endogenous urinary loss (EUN) plus part of the metabolic faecal nitrogen loss (MFN) plus loss of nitrogen in hair and scurf (D).The total is termed the basal endogenous nitrogen (BEN) and is of the order of 0.35 g/kg W° /day, which translates to a metabolisable protein demand of 2.19 g/kg Metabolisable protein is assmned... 

Figure 9.1 shows an overview of protein metabolism in addition to the dietary intake of about 80 g of protein, almost the same amount of endogenous protein is secreted into the intestinal lumen. There is a small faecal loss equivalent to about 10 g of protein per day the remainder is hydrolysed to free amino acids and small peptides, and absorbed (section 4.4.3). The faecal loss of nitrogen is partly composed of undigested dietary protein, but the main contributors are intestinal bacteria and shed mucosal cells, which are only partially broken down, and the protective mucus secreted by intestinal mucosal goblet cells (see Figure 4.2). Mucus is especially resistant to enzymic hydrolysis, and contributes a considerable proportion of inevitable losses of nitrogen, even on a protein-free diet.

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