Aiming at using Butyrivibrio fibrisolvens as a probiotic for dogs and cats, optimal conditions of freeze-drying to keep cell viability were determined. Highest percentages of viable cells were obtained by freeze-drying below -40°C. Sucrose and fructooligosaccharide had a high protective effect against cell damages during freeze-drying. The percentage of viable cells was maximum when cells were freeze-dried at the cell density of 10¹⁰ viable counts/ml. Refreeze-drying following the first freeze-drying enhanced the proportion of viable cells possibly because of complete dehydration. Approximately 80 % of cells were kept viable by freeze-drying under optimal conditions. Resistance of strains MDT-1, ATCC19171 and TH1 to damages during freeze-drying was higher than other strains of B. fibrisolvens, which indicates that these strains are suitable for probiotics in this context. When the freeze-dried cells of MDT-1 and TH1 were preserved at room temperature under air, more than 40 % of the cells were viable even after 3 months. When stored in a refrigerator (4°C) for 6 months, more than 80 % cells were viable. Little loss of viability was noted when stored in a freezer (-20°C) for 6 months, suggesting that the two strains can be kept viable for long periods of time. When freeze-dried cells of MDT-1 were grown in the presence of a small amount of oxygen, viable cells decreased. However, addition of Lactobacilus fermentum JCM1137 alleviated the loss of viability, suggesting that L. fermentum consumed oxygen. When B. fibrisolvens is utilized as a probiotic, it may be beneficial to use oxygen-consuming lactic acid bacteria simultaneously.

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In order to reduce nitrosoamine formation in the intestine of dogs, nitrosating activity of mixed intestinal microbes was examined with fecal samples collected from 30 dogs. The number of bacteria that have nitrosating activity tended to increase with the age of dogs irrespective of breed or sex. Incubation of dog feces with nitrite suggested that the growth of nitrosating bacteria and/or nitrosatingenzyme activity are enhanced by nitrite. However, since nitrosation was observed even when heat-killed fecal bacteria were incubated (non-enzymatic reaction), it is desirable to prevent the accumulation of secondary amines and nitrite in the intestines irrespective of whether or not intestinal bacteria are involved. Nitrate reductase in Escherichia coli has been reported to have nitrosating activity, but Selenomonas ruminantium and Wolinella succinogenes, nitrate- and nitritereducing ruminal bacteria, were shown to have little nitrosating activity. When mixed fecal bacteria from an old dog were grown with nitrite, addition of S. ruminantium stimulated nitrite reduction and decreased the nitrosating activity of the mixed fecal bacteria. These results suggest that a decrease in nitrite due to nitrite reduction by S. ruminantium brought about a decrease in nitrosatingenzyme activity. When mixed fecal bacteria were grown with nitrate, addition of W succinogenes that has a higher ratio of nitrite-reducing activity to nitrate-reducing activity than S. ruminantium, shortened the time during which nitrite was present. As a result, the nitrosating activity of the mixed bacteria decreased. Therefore, introduction of S. ruminantium and W succinogenes to the intestines may decrease nitrite accumulation or concentration, which may decrease nitrosoamine formation.

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The present study was performed to evaluate the effect of tea catechins on fecal odor and odorous compound in cats. Growing cats received 13.75 mg/kg body weight/day of tea catechins with dry and moist cat foods for three weeks (experiment 1) and 20.63mg/kg body weight/day of tea catechins with dry cat food for five weeks (experiment 2). Fresh feces were collected weekly (before and at weeks 1,2 and 3 of tea catechin administration) in experiment 1 and biweekly (before and at weeks 1,3 and 5 of tea catechin administration, and two weeks after administration was stopped)in experiment 2. Fecal odor intensity, ammonia and phenol compounds were measured. In addition, volatile fatty acids in feces were measured only in experiment 2. In experiments 1, although fecal odor intensity showed no regular pattern, fecal ammonia was decreased significantly by tea catechins. In experiment 2, fecal odor intensity increased during tea catechins administration, and remained high two weeks after administration was stopped. When fecal odor intensities on corresponding days (before and at weeks 1 and 3 of administration) in experiment 1 and 2 were compared, the values were greater in experiment 1 than in experiment 2, probably due to the difference in the protein content in the cat food: the protein content in moist cat food was higher than that in dry cat food. In experiment 2, fecal ammonia tended to increase during tea catechins administration and remained high two weeks after administration was stopped. Phenol compounds were not detected in feces in both experiments. Volatile fatty acids, such as, acetic, propionic, isobutyric, butyric, iso-valeric, valeric acids were detected in feces. Volatile fatty acids concentration was little affected by tea catechins administration. In conclusion, tea catechins administration could decrease fecal ammonia but has little affected on fecal odor intensity and odorous compounds other than ammonia in cats. In addition, it was suggested that fecal odor intensity may decrease with dietary protein level.

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The purpose of this study was to examine effects of CP source and CP level (Trial 1) and carbohydrate source (Trial 2) of dry cat food on apparent digestibility determined by the total fecal collection method and by the chromium oxide-indicator method, and on the difference in digestibility values between the both determination methods. In Trial 1 using 12 adult cats, four diets different in CP levels (29% vs 54% as-fed) and in CP sources (animal protein source vs vegetable protein source)were allotted to 4 groups of 3 cats each in a 4 X 4 Latin square design with 15 d per period. As a result, the magnitude of differences in the digestibility of DM, OM and CP between the determination methods was significantly less when cats received the higher CP diet. However, the CP source did not affect the magnitude of differences in apparent digestibility. In Trial 2 using 12 adult cats, a diet without any carbohydrate source (control diet), a diet containing corn (starch diet), and a diet containing cellulose and beet pulp (fiber diet) were allotted to 3 groups of 4 cats each in a 3 X 3 Latin square design with 12 d per period. The diets were restrictedly given to cats to equalize the dietary CP intake among the 3 groups. As a result, the magnitude of differences in the apparent digestibility of DM, OM and CP between the determination methods tended to enlarge when cats received the starch diet and the fiber diet, though not significant.

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For the promotion of health, especially the prevention of colorectal cancer in dogs, preliminary experiments were performed to gain basic knowledge on the conditions to maximize the effect of sphingomyelin (SM) and the involvement of intestinal bacteria in SM degradation. Feeding a die t containing SM to mice decreased the number of aberrant crypt foci (ACF) in the colon and rectum induced by 1,2 ?aimethylhydrazine. Analysis of sphingolipids in the feces of mice and dogs sugge sted that considerably large amounts of endogenous SM and its degradation products enter the intestinal tract. However, the amounts appeared to be insufficient to prevent colorectal cancer, which implies that dietary supplementation of SM is important. To exert effects, SM needs to be degraded to ceramide, and more desirably, to sphingosin, but SM and ceramide did not appear to be readily degraded in the intestinal tract. In mice, removal of intestinal bacteria with antibiotics did not alter the amount of fecal SM, suggesting that mice have few or no bacteria that have sphingomyelinase (SMase). However, the amount of fecal sphingosin was significantly reduced by antibiotics, suggesting that mice have bacteria having ceramidase. Evidence was obtained for the first time to show the presence of intestinal bacteria having SMase and ceramidase in dogs, although the percentage of dogs that possess such bacteria was low. The amount of fecal SM was smaller, and that of sphingosin was larger, in dogs that had bacteria having SMase and ceramidase, which suggests that these bacteria contribute to the degradation of SM and ceramide in the intestinal tract. These results show that introduction of bacteria having these enzymes to dogs can enhance the effectiveness of SM given in the diet.

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