To characterize the taste profiles of Poaceae as cat grasses, a method for analyzing plant taste using a taste sensing system was evaluated. Using this method, the gustatory characteristics of plants that cats may potentially encounter in their daily environment were identified. A total of 39 plant species from 15 families─including grasses, legumes, vegetables, fruits, plants associated with self-anointing behavior, and toxic plants for cats─were analyzed. Each plant (100 g) was processed using a food processor, after which ground cat food A and pure water were added and mixed. The aqueous layer obtained by centrifugation was used as the sample for taste analysis. The measurement error rate for each taste category was less than 50% and considered acceptable. Principal component analysis was performed based on the average taste values of each plant family. The results indicated that the initial taste of umami was distinct from other taste components. Hierarchical cluster analysis revealed that the Poaceae family classified as a group with relatively low sourness and bitterness, along with substantial umami and saltiness. In conclusion, the unique taste characteristics of the Poaceae family have been identified. The high level of umami in Poaceae may be attractive to cats, and that could be one reason why cats are able to accept Poaceae.

Consumption of soybeans has been reported to protect kidney function and is attributed to the anti-inflammatory effects of its components. In this study, we used specific proteases to enzymatically hydrolyze soy protein isolate. This process resulted in a digestion-resistant soybean protein rich in trace components, including phospholipids. Given that chronic kidney inflammation is associated with kidney and lower urinary tract diseases in cats, we aimed to investigate whether feeding resistant soybean protein to cats contributes to maintaining kidney and lower urinary tract health. We initially measured physical, blood, and seven other variables using urine test strips after feeding 10 clinically healthy young cats 1 g of resistant soybean protein daily for 7 days. The results showed that the levels of urea nitrogen and serum creatinine levels, indicators of kidney health, remained within reference ranges in all cats, with no adverse events being observed. Although urinary proteins, alkaline urine, and struvite crystal precipitation were initially observed in some cats, these symptoms were no longer detected by the end of the experiment. To assess the long-term effects of consuming resistant soybean protein, we subsequently examined the effects of feeding this protein (0.2 g/kg of body weight/day) to eight clinically healthy elderly cats for 30 days. Our observations revealed that the levels of symmetrical dimethylarginine, creatinine, and urea nitrogen, which serve as renal function markers, remained within the reference ranges, and no other adverse effects were observed. The results of these experiments indicated that feeding resistant soybean protein contributed to maintaining renal function without burdening the kidneys and prevented urinary stone formation in the lower urinary tract via the neutralization of alkaline urine. Further studies are needed to determine the mechanisms whereby resistant soybean protein protects the kidneys and lower urinary tract of cats and to assess the other health-beneficial effects of resistant soybean protein.

This study aimed to investigate the actual contents of calcium, phosphorus, and sodium in commercially available cat foods in Japan. We analyzed 12 dry and 12 wet complete diets, as well as 10 wet treats, for calcium, phosphorus, and sodium (calculated from salt content). No significant differences were observed in calcium, phosphorus, sodium contents, or the calcium-to-phosphorus ratio between dry and wet complete diets. However, some complete diets had a calcium-to-phosphorus ratio below 1.0, with a higher prevalence among wet products. This study revealed that certain cat foods available in Japan have a calcium-to-phosphorus ratio below 1.0 and some products did not meet the nutritional standards set by the European Pet Food Industry Federation (FEDIAF). These findings highlight the need for mandatory labeling of calcium and phosphorus contents, as well as consideration of adopting FEDIAF standards, to ensure accurate nutrient labeling of cat foods.

Obesity in cats has been associated with various diseases, making its prevention and management a critical concern. Carnosine and anserine, both imidazole dipeptides (IDPs) with antioxidant properties, are abundant in meat and fish. Previous studies have demonstrated that dietary carnosine supplementation exerts anti-obesity effects in cats. In this study, we measured the IDP content in 63 complete and balanced pet foods for adult cats (18 wet foods, 36 dry foods, and 9 obesity-management dry foods). The results showed a tendency toward lower carnosine, anserine, and total IDP content in dry and obesity-management dry foods compared with wet foods. A moderate positive association between total IDP content and protein content suggests that, considering major protein sources in cat food are meat and fish, the quantity of protein may be influential in IDP. In contrast, the carnosine-to-anserine ratio—expected to vary with ingredient composition—did not differ significantly among products. Because anserine concentrations exceeded those of carnosine in more than 60％ of the foods analyzed, further studies are needed to determine whether anserine also confers anti-obesity effects in cats.