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Conduct Science metabolic have dual food and water systems to allow for easy measurement of an animal’s intake. All cage components are autoclavable.

  • The funnel-and-cone design separates feces and urine for clean clear collection.
  • Multiple sizes available. Inquire for details
  • Autoclavable to 48 Degrees C

Documentation

An integral aspect of experimental research in the neurosciences is the direct handling of experimental animals, typically rodents. Though rodents are manageably easy to house, store, and take care of, often research protocols require stringent maintenance and control of food and water intake, as well as the collection and examination of non-contaminated samples of urine and fecal excretion. Keeping track of the metabolic processes provides a picture of the animal’s overall health and physiological status (Tarland, 2007), along with further information that may prove essential to experimental outcomes.

The metabolic cage (Engellenner et al., 1981) is an apparatus that offers a reliable means for management of intake and output data and consistent collection of urine and feces for periods of 24 hours or longer. First established for compiling feed tables for farm animals, the metabolic cage’s design has evolved with the purpose of extensive observation of metabolic function, and how different factors affect metabolic processes. The apparatus consists of a transparent, upper chamber with a grid floor where the rodent is held, a feed chamber located outside of the cage and an easy pull-out drawer to hold the liquid feed and a calibrated water bottle atop a calibrated spillage collecting tube. A separate chamber for urine and feces collection is located beneath.

The research on the usage of the metabolic cage in rodents suggests the likelihood of negative physiological effects caused by experiences of social isolation, grid floor, and absence of nesting material (Tarland, 2007). Even with these limitations, however, metabolic cage utilization remains an essential practice in animal research, being the only method providing total control over feed and water intake during long periods of observation.

Apparatus and Equipment

The metabolic cage setup consists of an upper cage or chamber made of transparent, gnaw-proof material such as polycarbonate, and an outer feed chamber with a pull-out drawer that prevents the disturbance of the animal during refill. The construction of the feed chamber and drawer also functions to prevent feed getting through the main chamber floor and causing contamination of urine and fecal samples. Attached to the apparatus is a calibrated water bottle located outside of the cage. A calibrated spillage collecting tube, used to calculate exact water intake, can be found just below the spout of the water bottle so as to prevent contamination of urine and fecal samples.

The main chamber has grid floors and is connected underneath to collecting tubes for urine and feces. The urine flow through the middle of a funnel and to a urine collection tube and the feces roll down the side of the funnel and to a separate fecal collection tube.

Protocol

Prior to metabolic cage utilization, rodents may first be typically housed in normal cages before being transferred to metabolic cages. Once individually-housed in metabolic cages, fecal pellets and urine are collected after a prescribed amount of time and immediately stored and refrigerated before analysis. The samples are weighed at the time of collection, whereas the subjects are weighed daily and after every sampling occasion (Eriksson et al., 2004).

Applications

Urine and feces collection are important experimental methods in determining the health of an animal. For instance, a clinical urine analysis may include measurement of pH, protein, glucose, bilirubin, hemoglobin and ketone levels (Tarland, 2007). Single sampling is a less complicated affair than what is more typical of experimental protocols which require 24-hour or longer periods of observation, necessitating the use of the metabolic cage. Metabolic cages are especially useful in experiments that involve analysis of biochemical, nutritional, toxicological, and physiological aspects of rodent behavior.

Strengths and Limitations

Metabolic cages are widely considered a useful tool in animal research, providing a means for extensive observation of factors that influence metabolic processes. The apparatus is fairly simple and straightforward, lessening complications in rodent housing and observation, as well as urine and fecal collection and analysis.

Housing in these cage types, however, have been seen to cause inconvenience to the animals. Research has shown that isolation-induced stress from the individual housing in metabolic cages cause age-dependent metabolic and behavioral responses in rats (Gil et al., 1998). Other studies have found evidence for stress from metabolic cage housing in reduced weight gains and increased fecal production (Eriksson et al., 2004). Other features of the environment have also been found to influence rodent welfare, such as the grid floor, minimized cage space, and lack of nesting material (Tarland, 2007). The rodents housed in metabolic cages are restrained from doing some of their natural behaviors, and the limitations that arise have an impact on the animal’s well-being as well as the reliability of research outcomes and must therefore not be overlooked.

Summary

  • The metabolic cage is an apparatus, and housing tool that provides a means for observation of metabolic function, control of food and water intake, and separate collection of urine and fecal samples for analysis in animal research
  • The apparatus consists of a transparent, upper chamber with a grid floor where the rodent is held, a feed chamber located outside of the cage and an easy pull-out drawer to hold the liquid feed, a calibrated water bottle atop a calibrated spillage collecting tube, and collecting tubes for urine and feces collection
  • Metabolic cages are especially useful in experiments that involve analysis on biochemical, nutritional, toxicological, and physiological aspects of rodent behavior

References

Engellenner, W. J., Rozboril, L., Perdue, V. P., Burright, R. G., & Donovick, P. J. (1982). A simple and inexpensive metabolic cage for mice. Physiology & behavior, 28(1), 177-179.

Eriksson, E., Royo, F., Lyberg, K., Carlsson, H. E., & Hau, J. (2004). Effect of metabolic cage housing on immunoglobulin A and corticosterone excretion in faeces and urine of young male rats. Experimental physiology, 89(4), 427-433.

Gil, M. C., Aguirre, J. A., Lemoine, A. P., Segura, E. T., Barontini, M., & Armando, I. (1999). Influence of age on stress responses to metabolic cage housing in rats. Cellular and molecular neurobiology, 19(5), 625-633.

Tarland, E. (2007). Effect of metabolism cage housing on rodent welfare (Doctoral dissertation, slu).

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