Because presence of nitrite in the intestines of animals can be a risk factor of carcinogenesis, nitrate and nitrite reduction by the intestinal microbes of dogs and cats was examined by using fecal samples. Incubation of dog and cat feces with nitrate indicated that all the animals examined had nitrate- and nitrite-reducing bacteria in their intestines. The ratio of nitrite reduction rate to nitr ate reduction rate was found to decrease with the ages of dogs and cats, suggesting that nitrite can be accumulated in senior animals. Nitrite reductase activity in mixed fecal microbes increased with an increase in nitrite concentration in the medium, suggesting that the synthesis of nitrite reductase is enhanced by nitrite. The optimal pH of nitrate and nitrite reduction by mixed fecal microbes was 7.0, and in a pH range of 6.0-7.2 nitrate reduction was faster than nitrite reduction, suggesting that nitrite can be accumulated within this pH range. Because nitrate reduction rate was low at a pH value below 6.0, it is desirable to keep the pH of large intestines around 6.0. When formate was added as an electron donor to cultures of mixed fecal microbes, the ratio of nitrite reduction rate to nitrate reduction rate was enhanced, suggesting that nitrite accumulation in the intestines can be prevented by increasing formate production by intestinal bacteria.

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Effects of dietary conjugated linoleic acid (CIA) during pregnancy and lactation on mater nal and offspring body weight, and liver condition of offspring were determined. Mice at 8weeks-of-age were divided into two groups. They were provided free access to one of two semi-purified diets containing 30 g CLA plus 70 g soybean oil/kg diet (CLA group) or 100 g soybean oil/kg diet (control group). At 9 weeks-of-age female mice were mated with male mice given the same diet. Female mice were fed the experimental diets until their offspring became 25 days old. The liver was removed from offspring and the triacylglycerol content was determined. Although body weight of dams was not significantly different between dietary groups, the body weight of offspring exposed to dams given CLA was lower compared with the controls. The relative liver weight and triacylglycerol content of offspring in the CLA group were significantly higher than those of control. These results suggest that CLA supplementation during pregnancy and lactation influences growth and liver lipid metabolism of offspring in mice.

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Two experiments were conducted to examine the effect of dietary contents of CP and carbohydrate (crude fiber and NFE) on water balance and capacity to form struvite crystals in urine of healthy adult cats. In Expt 1 (n=12), effects of the CP content were evaluated by ad libitum feeding of three dry diets containing CP at 29%,50% and 71% per DM. An increase in the dietary CP content resulted in increased water intake and urine volume, decreased urinary pH, and increased urinary pSAP that is a negative logalithm of struvite activity products given by[Mg²⁺]×[NH₄⁺]×[PO₄^3-]. Conversely, HCl-insoluble fraction of urinary sediment was increased, whereas struvite crystals in urine were decreased, by an increase in dietary CP contents. In Expt 2 (n=9), effects of the dietary carbohydrate content were compared among three groups similar in CP intake but different in carbohydrate intake. The control diet was the same as the CP71 diet used in Expt 1, and the other two diets were a high-starch diet and a high-fiber diet containing 52% CP per DM. Because the CP intake was adjusted to be almost similar in all groups, carbohydrate intake in the high-starch or high-fiber group was 2.5to 3 folds higher than that in the control group. As a result, water intake and urinary volume did not differ among the three groups. Comparing with the control group, high-carbohydrate intakes resulted in lower pSAP, and urinary pH was especially higher in the high-starch group. In addition, HC1-insoluble fraction of urinary sediment and struvite crystals in urine increased or tended to increase in the high-carbohydrate groups. These results suggest that, in contrast to dietary protein, dietary carbohydrate could stimulate the formation of struvite urolith in healthy adult cats. J. Pet Anim. Nutir, Vol.6 (No.1): 12-20,2 003

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