Collection of excreta

Ammonia may be produced and lost between deposition and collection of excreta in winter housing, during its storage and following land application. The treatment of excreta from winter-housed stock as a waste disposal problem rather than a fertilizer resource results in substantial loss of N as NH3. 

Collection of excreta and external secretions including sweat and uncannulated saliva, of placenta at delivery, and of amniotic fluid at the time of rupture of the membrane before or during labor... 

Subjects were all students or employees of the University of Nebraska who maintained their usual work, study and social activities except for the eating of the experimental diets and nothing else, making collections of excreta, giving blood samples, and filling out various questionnaires. All were assumed to be in good health as evaluated from health histories by medical personnel of the University of Nebraska Health Center. Signing of subject consent forms was required of all participants prior to participation. This project was approved for human subject participation by the University of Nebraska Institutional Review Board for the Protection of Human Research Subjects. 

Critical features of metabolism frequently require administration of radiolabelled material to man during ED. Such studies generally involve administration of single doses, with subsequent collection of excreta as well as blood sampling until virtually all drug has been eliminated. The clinical phase of such studies is generally not complex, but preparation for the study, with synthesis of the radioactive molecule and development of cold assays of metabolites as well as parent molecule, may take many months. Such studies also require submission of applications with detailed dosage and radioactive exposure calculations for authorisation by external bodies such as the Administration of Radioactive Substances Advisory Committee (ARSAC) in the UK. 

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. 

Studies that have included measurement of urinary and fecal excretion of radioactivity have helped to confirm these studies of total volumes of distribution of the thyroid hormones. When excreted radioactivity is subtracted from injected radioactivity and the result divided by plasma radioactivity (all in the same units and corrected for radioactive decay), the quotient is taken as the volume of distribution. The problem with this approach is that it is difficult to ensure complete collection of excreta. 

With subjects that produce discrete fecal pellets, collection of excreta is simple and straightforward. When possible, it is advantageous to keep insects in contain-... 

The development that has taken place is the result of 100-150 years of enormous investments. All over the world, this has left us with a sewer and treatment plant infrastructure that will be in use for an unknown future. We will still see developments in terms of technical improvements and sustainable solutions. However, we will not, as a general trend, see the wastewater collection and treatment concept replaced by, e.g., centralized collection of solid human excreta or on-site solutions. This could have been a realistic option for further development 150 years ago — not now ... 

Following dose administration, rats are placed in individual cages. The urine and feces that collect in containers are removed at predetermined intervals. The volume of urine and the weight of feces are measured. After the final collection, the cage is rinsed, normally with ethanol or water, to assure complete recovery of excreta. If the rats are also used for serial blood sampling, it is important that bleeding be performed inside the cage to avoid possible loss of urine or feces. 

Raw slurry was collected and prepared by diluting fresh excreta from fattening pigs with tap water to a standard concentration of total solids (TS) 30 g/1 and chemical oxygen demand (COD) 38 g/1. The methods of excreta collection, the animal diets, and the slurry... 

In addition to ARSAC approval, the protocol must also be approved by ethics committees in the normal manner for studies in man. The study should be conducted in between four and eight consenting subjects, in facilities where any spills of radiolabelled materials can be contained and monitored. Normally, subjects will be required to provide blood samples and to collect all excreta for a period determined by the known or estimated half-lives of the parent compound and metabolite. With cooperative subjects, recoveries of radioactivity should be close to 100%. Samples will be assayed for radioactivity and by cold chromatographic methods, and every attempt should be made to identify major metabolites... 

The greatest opposition to the new fibre is the result of the waste disposal problems it will produce. Vast quantities of excreta will be deposited by the animals and will presumably have to be collected and dumped. Have the risks to health been fully considered Will decomposition produce methane and a risk of explosions ... 

The nutrient balance technique, whether used for measuring N balance, calcium balance, or balance of other nutrients, is not particularly accurate. Inaccuracies are introduced with feeding. It may not always be possible to measure exactly how much food is consumed by the animal or human subject. Inaccuracies are introduced in collecting the excreta, especially as collections must be made over the course of many days. An important source of error is the fact that the value for N balance is determined by subtraction, that is, subtracting the amount excreted from that consumed. The values for balance, whether positive or negative, are often small compared to the values for the amount of nutrient consumed. 

Two studies discuss the acute absorption of radiolabeled maneb in rodents. The first study (Brocker and Schlatter 1979) used unfasted adult female rats dosed with [ " Mnjmaneb at a dose of 4-10 mg/kg. The rats were kept in metabolism cages which allowed the collection of respired air, urine, and feces for several hours post-dosing. The maneb was given alone or in conjunction with different metal compounds. Radioanalysis of excreta and selected tissues revealed that at 72 hours post-dosing, only 4-6% of the radioactivity was retained in the body with the majority of the label located within the liver and kidney. For 2 different chemical preparations of maneb, the recovery of label in feces was 94-96%, with the remainder in the urine. The respired air of two rats contained only 0.24 and 0.60% of the label, respectively. When molar excesses of the chloride salts of zinc, copper, iron, and mercury were added with the maneb. 

A classic technique employed in pharmacology and toxicology disposition studies for all routes of administration is the mass balance approach (Riviere, 1999). Mass balance analysis accounts for all of the topically applied dose of the compound, whether it is in the formulation, associated with the skin surface, penetrated into the stratum comeum, distributed into the carcass, or absorbed into and excreted from the blood into urine and feces. In this context, total recovery of 90% of the apphed dose is considered excellent recovery (Schaefer and Redelmeier, 1996). Mass balance studies are conducted by collecting all excreta after topical and parenteral administration. Data from a parenteral route such as intravenous dosing is required to correct for the fraction of absorbed compoimd appearing into the excreta collected if a precise estimate of bioavailability is to be determined and all routes of excretion are not collected (e.g., collection of urine and feces but not expired air) (Riviere, 1999). In such a study, absorption is calculated as follows ... 

Animals excrete urine and dung directly to land or it may be collected as manure and recycled. These different forms of excreta need to be estimated since they can be significant contributors to GHG emissions and to nutrient losses to waterways that affect eutrophication potential. For feed production, data are required on land used and external inputs, such as fertiliser and resources, for example, irrigation water. Emissions generated in feed production need to be accounted for (e.g. LEAP, 2014b) in wool LCA studies. 

It is more difficult, if not impossible, to collect excreta of insects with highly dilute or watery feces. The Mexican bean beetle, Epilachna varivestris, usually excretes droplets of feces that adhere to the foliage on which they feed. The Colorado potato beetle, Leptinotarsa decemlineata, also excretes watery fecal material that tightly adheres to leaf tissue when dry. For such species, estimates of excreta as a function of uric acid concentration (Bhattacharya Waldbauer 1970, see below) has been suggested (Kogan 1986) but has not been widely used. 

Crude papain, obtained as the dried exudate of the fruit and leaves of Caricapapaya L., Cari-caceae, Is usually found to have been contaminated during collection, drying, or storage by insects, rodent hair and excreta, botanical plant parts, sand, etc. and may thereby become further contaminated by harmful bacteria and enteric organisms. 

Individual metabolism cages are recommended for collecting urine and feces in oral dosing studies. Excreta should be collected for at least 5 elimination half-lives of the test substance. When urine concentrations will be used to determine elimination rates, sampling times should be less than one elimination half-life (taken directly from the bladder in IV studies) otherwise, samples should be taken at equal time intervals. 

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