Seyeon Chang

This nonrandomized sequential study evaluated nitrogen (N) balance, apparent nutrient digestibility, serum biochemistry, and indoxyl sulfate (IS)-related outcomes in ten healthy adult Beagles. Dogs received the crude protein (CP) 30% formulation for four weeks followed by the CP 18% formulation for four weeks; urine and feces were quantitatively collected during four consecutive days in each period. Analyzed dietary CP concentrations were 31.36% and 19.20% of dry matter. Daily urinary N excretion was lower in the second period (5.60 ± 0.35 vs. 3.34 ± 0.15 g/day; false discovery rate (FDR)-adjusted q < 0.001), as was calculated N balance (2.52 ± 0.39 vs. 1.04 ± 0.14 g N/day; paired p = 0.0022). The N retention percentages were 28.78 ± 4.45% and 20.66 ± 2.81%, respectively (p = 0.077; q = 0.132), and were not demonstrated to be equivalent. Apparent total tract digestibility of CP and most analyzed amino acids was lower in the second period. Exploratory daily urinary IS excretion was 3.08 ± 0.35 and 2.59 ± 0.36 mg/day, respectively (p = 0.394; q = 0.394). The analyzed indispensable amino acid concentrations of both diets met the dietary nutrient profile benchmarks evaluated in this study. However, the formulations differed in ingredients and predicted daily energy intake, and period was completely confounded with feeding order. These observations cannot establish an isolated effect of dietary protein, actual long-term body protein retention, or nutritional equivalence.

Gloiopeltis tenax is a red seaweed containing diverse polysaccharides and bioactive compounds with potential functional applications in animal nutrition. However, information regarding its physiological and microbiome-associated effects in companion animals remains limited. The present study was designed as an exploratory nutritional intervention to evaluate physiological responses associated with dietary G. tenax supplementation in healthy adult dogs using an integrated framework including nutrient digestibility, glycan-degrading enzyme activity, fecal microbiome profiling, and serum metabolomics. Ten healthy adult dogs were assigned to two dietary groups receiving nutritionally balanced diets containing either Ulva sp. (CON) or G. tenax (GT) at 1% inclusion for 16 weeks under standardized feeding and housing conditions. Nutrient digestibility, fecal glycan-degrading enzyme activities, fecal microbiome composition, predicted microbial functional profiles, and serum metabolomic responses were evaluated. No significant differences were observed in nutrient digestibility, fecal score, or general health-related parameters between groups, suggesting acceptable tolerability of dietary G. tenax under the present experimental conditions. Relative abundances of several bacterial taxa differed between groups, and glycan-degrading enzyme activities showed directional changes associated with dietary treatment. PICRUSt2-based analyses suggested potential differences in predicted carbohydrate- and glycan-associated microbial functional tendencies between groups. Serum metabolomic analysis additionally revealed alterations in several amino acid- and carbohydrate-related metabolites associated with dietary intervention. Collectively, these findings provide preliminary insight into microbiome- and metabolome-associated responses to dietary G. tenax supplementation in dogs. Although limited by the exploratory nature and relatively small sample size of the present study, the integrated multi-omics approach applied here may contribute to the development of functional evaluation frameworks for companion animal dietary ingredients. Further studies with larger cohorts and expanded functional analyses are warranted.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

This study evaluated age-related changes in nutrient digestibility in dogs and examined the effects of physiological development and dietary composition on digestive efficiency. Twenty Beagle dogs were assigned to three groups: puppies (<1 year; n = 8), adults (3–4 years; n = 8), and seniors (10–11 years; n = 4). All animals were fed diets formulated to contain identical nutrient levels that met or exceeded the minimum recommended nutrient requirements established by the Association of American Feed Control Officials. The digestibility of dry matter (DM), crude protein (CP), ether extract (EE), nitrogen-free extract (NFE), calcium (Ca), phosphorus (P), and amino acids were compared among the groups. The results showed that NFE digestibility was significantly higher in puppies, whereas CP digestibility was lower than that in adults and seniors, likely due to immature digestive function. In addition, EE digestibility was significantly lower in puppies, whereas P digestibility decreased with age. No significant difference was observed in Ca digestibility. Amino acid digestibility is lower in puppies, particularly for essential amino acids such as lysine, isoleucine, histidine, and arginine. These results indicate that age-related differences in digestive physiology and protein source affect nutrient utilization, providing a basis for developing life stage-specific nutritional strategies for companion animals.