Faeces collection

A marker which can be used in faeces collection. It is determined by flame photometry or by titration against ferrous ammonium sulphate following its conversion to dichromate. 

A quantitative faecal fat estimation may be performed. Faeces collections are made over three or five days, markers such as carmine or chromium sesquioxide being sometimes used to time the beginning and end of the collection. The patient may be placed on a known fat diet during the collection, enabling the fat balance to be determined. 

Figure 2. Pectins isolated from faeces of germfree rats (collecting period I).

Figure 3. High molecular and partially degraded pectins isolated from faeces of some conventional rats (collecting period II)...

The separation of faeces and urine beneath slatted floors in pig buildings by mechanically operated mesh belts has been shown to reduce odour emissions in the building and from the ventilation outlets. The system has other advantages in that the collection channels are much shallower than conventional channels and that welfare straw can be given to the pigs without blocking the slurry system. The system is now in use on farms. 

Figure 22.10 Reverse cholesterol transfer. High density lipoprotein (HDL) collects cholesterol from cells in various tissues/ organs the complex is then transported in the blood to the liver where it binds to a receptor on the hepatocyte, is internalised and the cholesterolis released into the hepatocyte. This increases the concentration in the liver cells which then decreases the synthesis of cholesterol by inhibition of the rate-limiting enzyme in cholesterol synthesis, HMG-CoA synthase. The cholesterol is also secreted into the bile or converted to bile acids which are also secreted into the bile, some of which is lost in the faeces (Chapter A).

Procedure. Depending on the diet allocation, weigh an appropriate quantity of the remainder of the marked feed and feed to the specified animal before its normal feed, ensuring all the marked feed has first been consumed. This could be at 21.30 h on the Monday of the collection week. Collect faeces samples 1.5 h before the first feed, then after 8 h, 12 h, and 18 h, and then at 2-h intervals until 01.30 h on Thursday, and at approximately 4-h intervals until 21.30 h Friday. A final sample is taken at 11.30 h on Saturday. 

Faeces samples were obtained from 86 healthy subjects (34 male, 52 female, age 30 8 years) to acquire a wide inter-individual range. All individual stools were collected in their entirety during a period of 5 days in plastic containers. They were weighed and, at the end, homogenised and pooled. Aliquots of stools are lyophilised and then stored frozen at -20°C until analysis. 

The measurement of digestibility in the bird is more complicated than in the pig, since faeces and urine are excreted together through the cloaca. As a result, it is necessary to separate the faeces and urine, usually by performing a surgical operation on the bird that allows collection of faeces in a colostomy bag. 

Biomarkers do not measure exposure directly, but are an indicator of absorbed dose. A biomarker of exposure is defined as a xenobiotic substance or its metabolite(s) or the product of an interaction between a xenobiotic agent and some target molecules(s) or cell(s) that is measured within a compartment of an organism and can be related to exposure. Urine, blood, nail, saliva, hair, and faeces are common media collected for biomarker measurements. Maternal biomarkers of exposure can also be measured in amniotic fluid and breast milk. These matrices can also provide a measure of exposure for children, both prenatally and postnatally. Biomarkers in first teeth have also been used to assess early childhood exposure, whereas biomarkers in meconium and cord blood have been used to assess in utero exposures. Biomarkers of genetic damage (e.g. DNA adducts) have been extensively used to assess exposure to genotoxic agents (Neri et al., 2006). 

A variety of in-vitro bioassay samples can be collected from an individual for the purpose of ascertaining whether an internal radionuclide deposition has occurred previously. Samples that may be collected and analysed for such a purpose include urine, faeces, hair, teeth, breath, tissue etc. 

Analysis of herbage (of forage) has sometimes been used to detect and identify radionuclides deposited from the atmosphere (Jackson et al., 1981). However, the problem arises that when the deposition rate is low, large areas of vegetation need to be sampled for detection. In the case of plutonium, an alternative is to collect the faeces of grazing animals such as cows, sheep and rabbits. Plutonium is very poorly absorbed by the mammalian gut and so virtually all that is ingested by an animal will appear in its faeces. Also, if the species selected obtains its food entirely by grazing, then the isotopic ratio Pu will be the same in the faeces as deposited on the... 

There are several other biological samples less commonly analysed these include bile, sweat, saliva, faeces, lung and bone. Of these, saliva analysis has gained in popularity, chiefly because this fluid is easy to collect. Volumes are low, however. The concentration of analyte in saliva is often quite close to that in plasma (although the pH difference between saliva and plasma means that for some ionised compounds it is significantly different). From the viewpoint of sample preparation, saliva can... 

The radiolabelled peptide under study was administered to rats as described above. The animals were then placed in separate glass metabolic cages, allowing reliable separation of urine and solid excreta. The animals had free access to standard diet and water. Two hours after injection of the peptide, the rats urinary bladders were emptied manually, and the urine and faeces were collected. The procedure was repeated at 24 and 48 h post-injection. 

Metabolism of five individual representative kavalactones were studied in rats following both oral and intraperitoneal routes at doses of 400 and lOOmg/kg, respectively. Samples collected ftom urine, faeces and bile were extracted with ethyl acetate, treated with a trimethylsilating agent and analysed by gas chromatography (Rasmussen etal., 1979). 

In the terminal ileum and colon the bilirubin conjugates arc attacked by bacteria to fomi a group of compounds which are known collectively as stercohiliiioaeii, most of which arc excreted in faeces. Some are absorbed and eventually re-excreted from the bixly by way of bile. Small amounts of these tctrapyrroles are found in urine in which they are known as urohilinof en. 

Zinc metabolic studies in which the difference between the total dietary intake and the total excretion in faeces and in urine, is measured over a period of several days. The difficulties of this procedure include problems of ensuring complete collections of excreta and measurement of losses in sweat, shed skin and hair. These losses although minor, may cause cumulative errors. Analytical problems caused by accidental zinc contamination are also a worry, although here the use of stable zinc isotopes and mass spectrometry or neutron activation is an advantage. 

Yessotoxin is much less toxic to mice after oral administration than after injection. No deaths were recorded in mice given yessotoxin by gavage at 1 [55], 2 [67], 10 [65], or 50 mg/kg [68], No deaths or signs of toxicity were seen in mice dosed orally with la-homoyessotoxin or 45-hydroxy-yessotoxin at 1 mg/kg [67], In a pharmacokinetic experiment, known amounts of yessotoxin were administered orally to mice. Urine samples were collected at hourly intervals. The mice were killed after 6 h, and tissues were harvested. Only trace amounts of yessotoxin were found in blood, urine, and tissues. Most was recovered from the lower intestine and faeces. The difference in toxicity between injected yessotoxin and that given orally may therefore simply reflect a lack of absorption from the gastrointestinal tract [68],... 

Similar problems arise with many metal working fluids. These are sprayed onto the cutting tools, fall into an open collecting vessel, and are recirculated. They are frequently contaminated with organic detritus such as food crumbs, and mice or rat faeces or urine. They may be topped up periodically with fresh oil and maintained at temperatures of 20-30 °C leading to rapid deterioration. The effect of bacterial metabolism is to break the emulsion into organic and aqueous layers, the oil is converted into fatty acids, the pH falls the emulsion becomes useless and may cause corrosion spots on the finished item. 

We have used data from experimental works carried out with tried and tested methodologies. In fish studies, the collection of faeces is an important issue as the leaching of faecal material may lead to an overestimation of the digestibility. Currently, only two reliable methods exist to collect fish faeces. The first one is based on rapid decantation (Cho and Slinger, 1978) while the second, developed by INRA, is more effective since it allows the continuous collection of faeces (Choubert et al., 1982). The INRA system is illustrated in the figure below. 

Figure 8. Machine for the continuous collection of faeces by filtration (developed by INRA).

Since the total collection of faeces corresponding to a given meal is difficult in aquatic animals, apparent digestibilities are measured indirectly by incorporating an inert marker, usually chromic oxide, into the feed. Recently, other markers such as acid-insoluble ash, crude fibre, polyethylene, alkanes, cholestane or rare earth metals have been used successfully. 

A digestibility trial was carried out using three sheep to determine the digestibility of hay. During the 10-day faecal collection period, feed intake and faecal output were recorded. Samples of hay and faeces were analysed in the laboratory ... 

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