Faecal output

In a digestibility trial, the food under investigation is given to the animal in known amounts and faecal output is measured. More than one animal (typically four) are used, because animals, even of the same species, age and sex, differ slightly in their digestive ability, and because replication allows more opportunity for the detection... 

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 ... 

In some circumstances the lack of suitable equipment or the particular nature of the trial makes it impractical to measure either food intake or faecal output directly. For instance, when animals are fed as a group or in a grazing situation, it may be impossible to measure the intake of each individual. However, digestibility can still be measured if the food contains some indicator substance that is known to be completely indigestible. If the concentrations of this indicator substance in the food and in small samples of the faeces of each animal are then determined, the ratio between these concentrations can be used to calculate digestibility. For example, if the concentration of the indicator increased from 10 g/kg DM in the food to 20 g/kg DM in the faeces, this would mean that half of the dry matter had been digested and absorbed. In equation form this is presented as ... 

External indicators such as chromic oxide may also be used to estimate faecal output rather than digestibility. In this application, the indicator is normally given for 10 15 days in fixed amoimts (e.g. administered in a gelatin capsule) and once its excretion is assimied to have stabihsed its concentration in faecal samples is determined. Faecal dry matter output (kg/day) is then calculated as ... 

For example, if an animal is given 10 g of chromic oxide per day and the concentration of indicator in the faeces is 4 g/kg DM, then faeces output would be calculated as 10/4 = 2.5 kg DM/day. If food intake is known, then dry matter digestibility could be calculated as (dry matter intake — faecal DM output)/DM intake. Alternatively, if DM digestibility is known, then dry matter intake could be calculated as faecal DM output/DM digestibility. The n-alkane technique is very useful in this context. As plants contain mainly odd-chain n-alkanes in their waxy cuticle, even-chain (C32) n-alkanes can be used as an external indicator to determine faecal output. At the same time, the odd-chain n-alkanes (C35) can be used to estimate diet digestibility. Dry matter intake can then be estimated in group-fed or grazing animals. 

The patients receive a dedicated low residue diet (Nutra Prep , E-Z-EM, Lake Success, NY, USA). This diet is provided in a box and supplies the patient with all the meals and drinks for the entire day before CT colonography (Fig. 4.2). This box contains powdered drinks with vanilla flavour, fruit drinks, soups, chips and nutrition bars. The diet reduces the fat intake and the faecal output. Patients are allowed to have breakfast (8 a.m.), lunch (noon) and dinner (5 p.m.). Breakfast consists of a tropical fruit juice, one vanilla drink and tea or coffee. At lunch patients drink another tropical fruit juice and vanilla drink and/or apple sauce, a soup and tea or coffee. At dinner they can have another soup and/or vanilla drink. Between the meals they can eat the chips and nutrition bars. The patients are allowed to drink as much additional water as they want to. 

Bajka BH, Gillespie CM, Steeb CB, Read LC, Howarth GS (2003) Applicability of the Ussing chamber technique to permeability determinations in functionally distinct regions of the gastrointestinal tract in the rat. Scand J Gastroenterol 38(7) 732-741 Bass P, Kennedy JA, Wiley JN (1972) Measurement of faecal output in rats. Dig Dis 17... 

Bravo L, Abia R, Eastwood MA, Saura-Calixto F. Degradation of polyphenols (catechin and tannic acid) in the rat intestinal tract. Effect on colonic fermentation and faecal output. Br J Nutr 1994 71 933-946. 

The final emulsification of dietary lipids into micelles (droplets that are small enough to be absorbed across the intestinal mucosa) is achieved by the action of the bile salts. The bile salts are synthesized from cholesterol in the liver, and secreted, together with phospholipids and cholesterol, by the gall bladder. As shown in Figure 4.15, some 2 g of cholesterol and 30 g of bile salts are secreted by the gall bladder each day, almost all of which is reabsorbed, so that the total faecal output of steroids and bile salts is 0.2—1 g/day. 

A 65-year-old man had been taking mefenamic acid for 2 years when he was admitted to hospital because of diarrhoea with severe steatorrhoea, some 50 g of fat being lost daily. When all drug therapy, including mefenamic acid, was stopped, the diarrhoea ceased within 2 days. The faecal output was normal 2 weeks later (89 ). 

Antigen Molecular weight (kDa) Identity Sheep breed Faecal egg output Worms References... 

Progress towards human trials raises the thorny question of how to evaluate vaccine success in humans, because protection in experimental animals has almost invariably been measured by worm recovery. One exception was the small-scale attenuated vaccine trial in chimpanzees (Eberl et a/., 2001), where estimates of protection were based on faecal egg output and circulating antigen levels but could not be validated against worm burden for ethical reasons. More recently, these indirect estimators of worm burden have been evaluated with respect to actual recoveries in baboons exposed to the attenuated vaccine, revealing their significant overestimation of protection levels (Kariuki et al., 2004). This issue needs to be addressed before we proceed to full-scale vaccine trials for schistosomiasis mansoni but may be less crucial for schistosomiasis haematobia where egg output in the urine is easier to measure. 

Ihler C F, Bjorn H 1996 Use of two in-vitro methods for detection of benzimidazole resistance in equine small strongyles. Veterinary Parasitology 65 117-125 Jacob D E, Huchinson M J, Gibbons L M 1995 Equine cyathostome infection suppression of faecal egg output with moxidectin. Veterinary Record 137 545... 

Copper is present in all metabolicaily active tissues. The highest concentrations are found in liver and in kidney, with significant amounts in cardiac and skeletal musele and in bone. The liver contains 10% of the total body content of I2(X) (.unol (80 mg). Excess copper is excreted in bile into the gut. and the faecal copper output (12.5 imol/24 h) is the sum of unabsorbed dietary copper and that re-excreted into the gut. 

Chitosan also has hypocholesterolemic effects and acts as an adjuvant to weight loss in rat studies [31,32]. Studies have reported that chitosan reduced the concentration of plasma cholesterol in animals [33,34] and type If diabetes patients in combination with hypercholesterolemia [33]. This property is being attributed to the positive charge of the molecule that binds to fatty acids (released from consumed fat) and bile salt components, which results in disrupted lipid absorption in the gut [5]. Also, chitosan is dissolved in the stomach, emulsifying the fat and forming a gel in the intestine which entraps fat and prevents intestinal absorption [35,36]. Chitosan forms a floccule in the duodenum which entraps dietary oil [37]. However, these effects are still controversial [31,38,39]. Actually, van Bennekum et al. [32] suggested that the incorporation of chitosan in the diet of rats reduces cholesterol (food) intake, but did not affect either intestinal cholesterol absorption or faecal sterol output. 

Were it not for the fact that fibre in the diet increases faecal weight, people s attention might never have been drawn to this relatively minor component of the diet. It has been known since ancient times that when wholewheat products were consumed, then a predictable increase in stool output occurred. Many investigators have now shown that fibre, especially wheat fibre, will increase faecal weight. In fact the majority of studies have concentrated on the effect of bran or other forms of wheat fibre, probably because it is a readily available concentrated form of fibre, to the exclusion of other types. Figure 2 shows a typical example of such a study Seven healthy male student... 

A multivariate analysis was conducted that included N intake and ME intake as covariates in predicting N output in faeces, urine and milk. Metabolizable intake had a significant effect on predicting urinary N excretion and milk N secretion but not faecal N excretion. It should be noted that ME intake already includes faecal and urinary energy as part of the calculation, therefore, correlations are expected. The residual standard deviations from the multivariate arralysis including ME intake as a covariate were 13.8, 27.9 and 15.0 g/d. The prediction equations for urinary N excretion and milk N secretion (which had significant effect of ME intake) were ... 

Several studies have highlighted the wide variation in N excretion, particularly urine N. Weiss et al. (2009) reported that the variation in urinary N was 3.5 times greater than for faecal N excretion and Mills et al (2009) also found that there was greater variation in N excretion relative to milk yield. The residual standard deviations for N losses in faeces, urine and milk in the present study were estimated to be 14.6, 32.5 and 17.5 g/d, respectively from the univariate analysis. The higher residual standard deviation for urine N compared to faeces or milk output presents an opportunity to manipulate diets to reduce urine N excretion and may be, in part, explained by metabolizability of the diet. 

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