Lens luxation in a CD-1 mouse.

Lens luxation was found in a male CD-1 (ICR) mouse. Ophthalmologic examinations revealed conical cornea anterior synechia and corneal neovascularization in the right eye. The lens was dislocated heterocentrically within the posterior chamber. Histologically, anterior lens luxation and adhesion between the iris and cornea were observed.

Coprophagy in rabbits: autoingestion of hard feces.

The rabbit is a representative animal species that conducts coprophagy, i. e. the production and reingestion of soft feces. We, however, encountered a maternal rabbit eating its own hard feces. A detailed investigation was performed on coprophagy in the rabbit to elucidate whether rabbits actually reingest their own hard feces. It was found that young adult Japanese White rabbits reingested their hard, as well as soft, feces directly from the anus. It has been reported that rabbits reingest only soft feces because of their high nutritive content, but the present study demonstrates that rabbits also reingest their hard feces despite their low nutritive content. It seems possible that coprophagy may be initiated by the colonic or rectal wall expanding effects of the fecal material itself.

Effects of prevention of coprophagy on pregnant mice--is coprophagy beneficial on a balanced diet?

The effects of prevention of coprophagy on reproductive performance were examined in ICR mice. Females were treated with restrainers in order to prevent them from ingesting their feces from day 1 through day 17 of pregnancy. The restrained animals fed a commercial diet did not show any clear adverse effects. In contrast, restrained dams fed a purified diet deficient in vitamin B12 exhibited stillbirths (14%) and abortions (7%). Restrained dams fed a diet lacking in vitamin B12 and folic acid also experienced frequent abortions (27%). In addition, six out of 14 restrained dams (43%) aborted when fed a vitamin B complex-deficient diet. Sham-restrained animals, fed the vitamin B complex deficient-diet, but able to ingest their feces trapped by smaller-mesh floors, escaped these adverse effects. Sham-restrained animals fed the commercial diet, however, showed only a slight improvement in their reproductive performance. In conclusion, coprophagy has nutritional significance as long as the diet is lacking at least B vitamins, especially vitamin B12 and folic acid, whereas it almost entirely loses its nutritional significance when the mouse has access to a balanced diet such as the one made available to the laboratory mice in the present study.

Coprophagy in female mice during pregnancy and lactation.

Coprophagy in female mice was observed predominantly in the reproductive stage. Female mice exhibited coprophagy more frequently during pregnancy and ingested larger amounts of feces during pregnancy and lactation than when they were not pregnant. Feces were found to be rich in vitamin B12 and folic acid. However, there were no marked fluctuations in the levels of either vitamin in the feces during pregnancy or lactation as compared with levels when animals were not pregnant. Acceleration of coprophagy during pregnancy and lactation seemed to correlate with the increased nutritional requirements of females during the reproductive stage.

A simple method for prevention of coprophagy in the mouse.

A series of studies of coprophagy in mice has been conducted from the viewpoints of behaviour and nutrition. Since it was necessary to prevent coprophagy to investigate its significance, an attempt was made to devise a restrainer. A polyethylene bottle was cut and fixed to the mouse so as to prevent its head from reaching its anus when faeces were excreted. The animals were also housed in cages with floors of larger mesh size in order to let the faeces fall through.

[Lifelong coprophagy in male mice].

Changes in coprophagy with age were investigated in male ICR mice during their life span. Sucklings showed coprophagy at 17 to 18 days old, i.e., a few days after they began to excrete feces autonomously. The number of fecal pellets ingested peaked at 5 to 6 weeks old (13 pellets/day) and gradually decreased, thereafter (2.1 pellets at 78 weeks old, 1.5 pellets at 104 weeks old). The diurnal pattern of coprophagy also changed with age. Growing mice showed vigorous coprophagous activity in both light and dark phases, whereas animals over 30 weeks old exhibited less activity in both phases, especially in the dark phase. Feces proved to be abundant in vitamin B12 and folic acid throughout the life span. These results suggest that the frequency of coprophagy changes in association with the nutritional requirements of mice during the process of growth or aging.

[Coprophagy in the germfree mouse].

Coprophagy was observed in germfree (GF) ICR mice of both sexes, and the results were compared with those of conventional mice. Frequency of coprophagy per animal per day in GF mice was 5.1 in males and 5.8 in females. In conventional (CV) mice, the frequencies were 6.2 in males and 5.3 in females (data from Zoological Science 2:249-255, 1985), with no significant differences compared with GF mice. Coprophagy in CV mice was frequently observed during 6-8 hr after lighting, whereas such close time relationships tended to weaken in GF animals. In a comparison of levels of constituents per unit weight between feces and diet, fecal crude protein and crude fat exhibited lower values than those in the diet. Levels of fecal crude ash and crude fiber were higher than those in the diet, and nitrogen-free extract was almost equal to that in the diet. No essential difference in these tendencies was found compared with CV mice. Levels of fecal vitamin B1, B2, B12 and folic acid were lower than those in the diet. In CV mice, except for vitamin B1, these vitamins exhibited either almost equal or much higher levels compared with those in the diet (data from Experimental Animals 35: 381-386, 1986). From the fact that coprophagy was observed in GF mice, it is suggested that the behavior is inherent in the mouse.

[Analyses of constituents of feces and the effect of a vitamin B12 fortified diet on coprophagy in the mouse].

In order to investigate coprophagy from the viewpoint of nutrition, fecal constituents were analyzed in freeze-dried samples. Feces were collected from 7:00 to 11:00 and from 19:00 to 23:00. Inorganic elements and crude fibers per unit weight were 3-4 times more concentrated in feces than in basal diet, whereas, crude proteins, crude fats and nitrogen-free extract showed various degrees of reduction. There were no differences in these tendencies with sampling time. As for some B vitamins, feces collected from 7:00 to 11:00 contained 22-92% more vitamins than feces collected from 19:00 to 23:00. In comparison with the dietary concentration, vitamin B12 was increased by 124-197 times (520-730 micrograms/100 g) in feces collected between 7:00 and 11:00. Folic acid in feces collected between 7:00 and 11:00 was 10 times greater than that in the diet. On the basis of the findings on vitamins, the effect of a vitamin B12 fortified diet (1,350 micrograms/100 g) on coprophagy was examined. Mean frequency of coprophagy per animal per day was 9.6 when animals were fed on the basal diet, whereas the frequency was immediately and significantly (p less than 0.05 approximately p less than 0.01) reduced to 4.7 after the diet had been replaced by the fortified one. However, coprophagy was not completely inhibited by vitamin B12 fortification. This indicates that some nutrient(s) in feces other than vitamin B12 might be of use to the host, and that otherwise, coprophagy might be a basically habitual form of behavior. Furthermore, under the fortified diet, the frequency of coprophagy increased gradually.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of removal of the olfactory bulbs on the estrous cycle of the mouse].

The effects of removal of the olfactory bulbs on the estrous cycle and the weight of reproductive organs were examined in mice of the IVCS, ICR and C57BL/6 strains. Sham-operated and intact mice served as controls. Virgin female mice were surgically deprived of the olfactory bulbs at 8 weeks of age and caged individually in air-conditioned rooms with controlled lighting (14 hours of light, from 5 a. m. to 7 p. m., each day). Vaginal smears were observed daily. The animals were killed and their principal organs weighed at 6 weeks after the operation. The results obtained were as follows; 1) The olfactory bulb ablation prolonged the length of estrous cycle of mice of the ICR (6.0 days) and C57BL/6 (5.0 days) strains, but did not modify the cycle in those of the IVCS strain (4.0 days). 2) A decrease of ovarian weights by this operation was observed in the mice of the IVCS and ICR strains, but not C57BL/6 strain.

[Activity patterns of diurnal drinking behavior in male mice (author's transl)].

Activity patterns of diurnal drinking behavior in male mice aged 12 to 20 weeks of IVCS, C3H/He and C57BL/6 strain were investigated in 14 : 10 light-dark alternation, thus showing regular 24-hr rhythms. The activity pattern of drinking behavior differed considerably among three strains. The highest activity of drinking behavior in IVCS mice was recorded around the time for lighting on and off, while in C3H/He and C57BL/6 mice it tended to be shown in the dark phase.

[Methods for intravenous injection and blood collection in the guinea pig via veins of the forelimb without anesthesia (author's transl)].

Methods for intravenous injection and blood collection by way of the forelimb in guinea pigs without anesthesia were investigated, with the results as follows: 1) Both the accessory cephalic and cephalic veins were found available for injection as well as for drawing blood samples. Venipuncture was accomplished with greater ease by using the accessory cephalic vein. 2) The following procedure has proven practical. (i) Clip the hair over the site. (ii) Restrain the animal to immobilize the foreleg in slight extension by grasping it at the elbow joint with the thumb and forefinger over its dorsal and ventral aspects, respectively. (iii) After disinfecting the skin surface with alcohol, perform injection using an appropriate syringe with a 27 (1/4) or 25 (1/3) gauge intravenous needle, or puncture the vein with a 23 (1/2) gauge i. v. needle to collect the blood that drips out.