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We investigated the influence of coprophagy on the calcium metabolism of the rat. 20 experimental animals were prevented from coprophagy by wrapping them in leather harnesses and compared with 21 controls on the same food intake. Kinetics of calcium metabolism were analysed using45Ca as tracer.

Chronic, five times weekly administration of lidocaine (60 mg/kg, i.p.) to rats resulted in the progressive development of abnormal eating behavior and seizures. Experimental rats became omniphagic, eating significantly more feces, straw, and gauze than controls. Following an average of 15 lidocaine injections unassociated with seizures, animals began to have major motor convulsions, which then increased in frequency and duration. A pharmacological kindling mechanism is suggested for the progressive effects of lidocaine on behavior and seizures.

Rats were gavaged with 144CeCI3 and either prevented from or allowed to practice coprophagy. Whole-body retention data varied widely and, in some instances, resulted in highly erratic patterns and enhanced gastrointestinal tract absorption of gavaged 144Ce in copraphagy-allowed rats. Greater whole-body retention of 144Ce was observed in coprophagy-allowed animals kept in solid plastic shoe box-type cages than in those kept in wire-bottom cages, owing to their continued access to the radioactive feces excreted within the first days after 144Ce gavage. Potential influences of coprophagy on results of experiments involving toxic materials are discussed.

Adult male rabbits, wearing a plastic collar to prevent coprophagy, excreted soft faeces during the first half of the light phase, starting at about the time the light switched on at 0600. While soft faeces were being excreted, food intake was reduced considerably in collared as well as in non-collared animals. Rate of passage of gastrointestinal contents in the rabbit was extremely high. Chromic oxide appeared in the faeces 4-5 h after it had been ingested in pelleted food. Coprophagy had no effect upon the rate of passage of gastrointestinal contents, and chromic oxide passed through at the same rate, whether it was incorporated in soft faeces or in pelleted diet.

Fifty-nine male Sprague-Dawley rata were subjected to an end-to-side portacaval shunt and compared with appropriate controls. During the first ten days after the operation, the liver weights decreased from an average of 4.2 to 2.3% of the body weight and thereafter remained at this level. Testicular atrophy also occurred regularly but only after the tenth postoperative day. Three weeks after the operation, the body weight of shunted rats had decreased by an average of 20%, whereas sham operated controls gained 17%. These changes were related to food intake and coprophagy. Hyper-ammonaemia developed gradually and levelled off at about 500 (μg/100 ml. Other alterations were more variable in severity. Spontaneous motor activity decreased to 12–77% of the preoperative value and was significantly correlated with changes in body weight. The electrocorticographic pattern was characterized by an average increase in rapid waves to 205% after five to six weeks, whereas the slow waves remained unchanged. These studies have established a standard of reference for further investigations with this animal model.

Quantitative analyses of protozoans provided estimates of caecal populations before and after periods of hibernation in squirrels. In Citellus lateralis and C. beldingi, Entamoeba citelli is lost from the caecum during hibernation, whereas Entamoeba sp. (similar to E. muris) survives. Animals removed from the cold room while torpid failed to regain infections of E. citelli after resumption of normal activity. Both amoebae survived in caeca of animals kept active throughout winter at warmer temperatures. Few cysts of either amoeba were passed by active animals. The average number of cysts passed (0.42/pellet) was not increased by short periods of starvation. After the first week of hibernation, no cysts were recovered. Viable cysts of Entamoeba citelli were recovered from dried feces stored for 168 days. Cysts of Entamoeba sp. from the same feces were nonviable. This exceptional ability to survive may be due in part to the uniquely thick cyst wall of E. citelli. Ingestion of feces containing cysts was observed in animals not infected with Entamoeba. Several of these animals acquired infections and began passing cysts within 1 month. E. citelli survives winter as an infectious cyst outside its hibernating host. Reinfection occurs in the spring when hibernation is over.

The fate of S35 after oral administration of labeled sodium sulfate to rabbits has been studied together with the effect of collaring to prevent coprophagy upon S35 uptake and excretion. Approximately 65 % of the S35 was excreted in the urine within 4 days. Cartilaginous tissues and red bone marrow showed the greatest uptake of S35, while brain and muscle showed the lowest activity. Collared rabbits showed much lower S35 uptake in liver, muscle, brain, and blood than uncollared rabbits.

The effect of coprophagy prevention and antibiotics on acetyl- choline levels of kidney, brain and small intestine in weanling rats fed choline- deficient diets was studied. It was found that 5 to 6 days of dietary choline deficiency resulted in decreased concentration of acetylcholine in kidney (64% ), brain (28% ) and small intestine (30% ). Coprophagy prevention or the inclu sion of antibiotics in the diet maintained the tissues' acetylcholine at normal or near-normal levels in the choline deficient rats. These results are similar to those which have been obtained by others in germfree rats. J. Nutr. 101: 25â€"28, 1971.

SUMMARY A description is given of an inexpensive metabolism cage, in which powdered diets can be fed without measurable loss. Coprophagy is completely eliminated in rats fitted with a new design of tail cup, and in this way total collections of faeces and urine are readily achieved. Cups of a similar design have been fitted both to young male and to adult female rats, and use over periods of several weeks has revealed no ill effects. Reproducible estimates of dietary protein quality have been obtained with collection periods as short as 48 to 96 hours, and growth rates are quite good in adequately and uniformly heated rooms. 67 The principal purpose of screen-floored metabolism cages for nutritional studies in mammals is to allow urine and faeces to be quantitatively and separately collected, and several types of cage for rodents have been marketed or described. Not only is such equipment relatively expensive, but it frequently involves the excreta coming into contact with a considerable area of cage surface during the collection and separation process. This inevitably leads to loss of excreta by oxidation and deamination through spreading out on large surfacesin contact with the atmosphere. The use of tail cups in rodents partly avoids this problem. Without cups coprophagy is only slightly reduced by caging on screen as opposed to solid floors. Barnes, Fiala, McGehee & Brown (1957) estimated that 50-65 per cent of faeces are ingested by rats on screen floors. Coprophagy not only delays the ultimate excretion of compounds of dietary origin (or their products), but may alter the quantitative utilization of a nutrient and allow some diet to be utilized in a form chemically modified by the intestinal flora. This flora in turn may be changed as a result of coprophagy (Fitzgerald, Gustafsson & McDaniel, 1964). The consequences of these effects are that the degree of dietary utilization may be altered and the time required to obtain a given degree of precision in metabolic studies may be extended in the coprophagous animal. Furthermore, the

Dogs excrete most of an i.v. dose of 14 C-indomethacin unchanged in their feces. Monkeys extensively metabolize the drug to deschlorobenzoylindomethacin and excrete it in urine, and rats, without coprophagy, excrete the major metabolite, desmethylindomethacin, equally in urine and feces. 14 C-indomethacin constitutes the major radioactive species in plasma, liver and kidney of rats and monkeys. In both species, a new lipid-soluble metabolite of indomethacin was observed. The half-life of the drug in plasma varied among the three species ranging from minutes in monkeys and dogs to hours in rats. In rats, plasma clearance of indomethacin by liver, although low, was thirty times the clearance rate by kidney, and the reabsorption of indomethacin from the intestine was extensive. Desmethylindomethacin, the major metabolite, was cleared from plasma equally by liver and kidney and was not reabsorbed from the intestine of rats. Consequently, this metabolite was distributed equally in urine and feces. Indomethacin was extensively and rapidly secreted in bile by dogs, eventually excreted as unchanged drug in their feces, and minimally metabolized to deschlorobenzoylindomethacin, which was excreted in urine. Monkeys were similar to dogs in that the liver was more than ten times as effective as the kidneys in clearing total radioactivity from plasma. However, they differed from dogs in that all drug species were maximally reabsorbed from the intestine. These differences in the plasma clearance of indomethacin and its metabolites by liver and kidney and in the entero-hepatic circulation of these drug species were sufficient to account for the species differences in the distribution and excretion of indomethacin.

SUMMARY In one experiment 100 Californian x New Zealand White rabbits were divided into two groups. One group was fed on a basal diet containing about 13.9 per cent protein and the second received a diet containing 0.75 per cent urea, but less vegetable protein, to give approximately the same nitrogen content. In a second experiment 196 rabbits of a similar type were divided into four groups. The first two groups were fed the same diets as in the first experiment while the third received the first diet plus 10 mg/lb of oxytetracyline hydrochloride and the fourth the second diet plus a similar antibiotic addition. In the first experiment liveweight gains during feeding periods of 8 weeks and of 6 weeks duration showed that the rabbits receiving the basal diet grew significantly more rapidly than did those fed the diet containing urea. The findings in the second experiment indicated that the antibiotic feeding did not significantly affect the growth rate on either ration, and, particularly, that the antibiotic did not significantly influence the response to the urea in the ration.

SummaryA metabolism cage for mice or hamsters is described which affords a separation of urine ancl feces, and nhich prevents coprophagy.

When a diet containing raw soybean was fed to rats, there was an increase in the synthesis of pancreatic protein, presumably exocrine protein, as evidenced by an increased uptake of [35S]cystine. There was also an increased transsulfuration of methionine sulfur as indicated by labeled sulfur transformation from methionine to cystine. This same pattern of events was produced in rats receiving a casein-containing diet when 50 mg of crystalline trypsin inhibitor was administered by gavage. However, if coprophagy was prevented, the increased uptake of [35S]cystine and [35S]methionine transsulfuration under both dietary conditions was blocked. It was found that prevention of coprophagy was without effect upon these two processes if supplementary dietary cystine was provided or if a dietary protein source with adequate cystine, i.e., heat-treated soybean, was provided. It was concluded that by practicing coprophagy, sufficient fecal cystine was being returned to the upper intestinal tract to permit some synthesis of pancreatic exocrine protein and with this stimulation of synthesis, transulfuration could proceed. This assumes that the biosynthesis of cystine is dependent upon the availability of sufficient cystine to permit active protein synthesis. In another situation where cystine requirement is high, namely, the rapidly growing rat, a limited amount of cystine was fed by providing a 12% casein diet. Either supplementary cystine or methionine was provided and it was found that both amino acids gave optimal growth in conventional rats, but when coprophagy was prevented, optimal growth was achieved only with the cystine-supplemented diet.

Several methods for measuring cholesterol absorption in the rat have been compared. After administration of an oral dose of labeled cholesterol ((14)C or (3)H) and an intravenous dose of colloidal labeled cholesterol ((3)H or (14)C) the ratio of the two labels in plasma or whole blood 48 hr or more after dosing compared closely to the ratio of areas under the respective specific activity-time curves. The area ratio method is independent of a time lag between the appearance of oral and intravenous label in the bloodstream. Both measures of cholesterol absorption agree fairly well with a method based on measuring the unabsorbed dietary cholesterol in a pooled fecal sample. The plasma isotope ratio method gave more reproducible results than the fecal collection method when the measurement was repeated in the same animals 5 days after the first measurement. Cholesterol absorption was overestimated by the use of Tween 20-solubilized labeled cholesterol for the intravenous dose. The plasma disappearance curves of injected labeled colloidal cholesterol and cholesterol-labeled chylomicrons infused intravenously over a 3.5-hr period in the same animal coincided within experimental error from the first day until 75 days after injection. The plasma isotope ratio method for cholesterol absorption gave the same results in rats practicing coprophagy as in those in which this practice was prevented. The addition of sulfaguanidine to the diet lowered cholesterol absorption as measured by the plasma isotope ratio to the same degree as that measured by the fecal collection method.

SummaryAnimals were fed diets free of threonine, lysine or protein with or without tail cups to prevent coprophagy. The animals fed the threonine- and protein-free diets lost weight rapidly whereas those fed the lysine-free diet lost weight slowly regardless of whether coprophagy was prevented or not. It is concluded that the modest weight loss caused by the lysine-free diet is not due to the availability of lysine from fecal material.