Serum metabolites, ghrelin and leptin are modified by age and/or diet in weanling kittens fed either a high- or moderate-protein diet.

The objective of this study was to evaluate the effects of in utero and postnatal exposure of a high-protein (HP; n=9) or moderate-protein (MP; n=16) diet on growth, and serum metabolite, ghrelin and leptin concentrations during the first 4 months of life in kittens. It was hypothesized that blood indices would be modified due to diet. Blood samples were collected from kittens at 4, 8, 12 and 16 weeks of age. Kittens were weaned at 8 weeks of age onto the same diet as the dam. Body weight was measured weekly from birth and daily food intake for each litter was recorded post-weaning. Serum concentrations of urea nitrogen, total protein and triglycerides were greater (P<0.05) in kittens fed the HP diet. Serum cholesterol concentrations were greater (P <0.05) in MP-fed kittens at 4 weeks of age. Moderate-protein fed kittens tended to have greater (P < 0.10) serum ghrelin concentrations. Leptin concentrations were not affected by diet, but changed over time (P<0.05). Our data indicate that diet and age of kittens affect circulating concentrations of peptides important in appetite regulation. Further research testing the effects of in utero and early postnatal nutrient exposure on feline obesity risk in adulthood is needed.

Phylogenetic and gene-centric metagenomics of the canine intestinal microbiome reveals similarities with humans and mice.

This study is the first to use a metagenomics approach to characterize the phylogeny and functional capacity of the canine gastrointestinal microbiome. Six healthy adult dogs were used in a crossover design and fed a low-fiber control diet (K9C) or one containing 7.5% beet pulp (K9BP). Pooled fecal DNA samples from each treatment were subjected to 454 pyrosequencing, generating 503,280 (K9C) and 505,061 (K9BP) sequences. Dominant bacterial phyla included the Bacteroidetes/Chlorobi group and Firmicutes, both of which comprised ∼35% of all sequences, followed by Proteobacteria (13-15%) and Fusobacteria (7-8%). K9C had a greater percentage of Bacteroidetes, Fusobacteria and Proteobacteria, whereas K9BP had greater proportions of the Bacteroidetes/Chlorobi group and Firmicutes. Archaea were not altered by diet and represented ∼1% of all sequences. All archaea were members of Crenarchaeota and Euryarchaeota, with methanogens being the most abundant and diverse. Three fungi phylotypes were present in K9C, but none in K9BP. Less than 0.4% of sequences were of viral origin, with >99% of them associated with bacteriophages. Primary functional categories were not significantly affected by diet and were associated with carbohydrates; protein metabolism; DNA metabolism; cofactors, vitamins, prosthetic groups and pigments; amino acids and derivatives; cell wall and capsule; and virulence. Hierarchical clustering of several gastrointestinal metagenomes demonstrated phylogenetic and metabolic similarity between dogs, humans and mice. More research is required to provide deeper coverage of the canine microbiome, evaluate effects of age, genetics or environment on its composition and activity, and identify its role in gastrointestinal disease.

Influence of feeding raw or extruded feline diets on nutrient digestibility and nitrogen metabolism of African wildcats (Felis lybica).

The African wildcat is one of the closest ancestors to the domestic cat and is believed to have similar nutrient requirements, but research is lacking. The objective of this study was to determine the effects of feeding a high-protein extruded kibble diet vs. a raw meat diet on nutrient digestibility, nitrogen metabolism, and blood metabolite concentrations in African wildcats. Five wildcats were randomized onto either a high-protein (>50% crude protein) extruded kibble diet or a raw meat diet. The study was executed as a crossover design, with 21-d periods, consisting of a 16-d adaptation phase followed by a 4-d total fecal and urine collection phase. Cats were housed individually in metabolism cages and fed to maintain body weight (BW). A fresh fecal sample was collected for short-chain fatty acid (SCFA) and branched-chain fatty acid (BCFA) analyses. Blood was analyzed for serum chemistry and leptin concentration. Food intake (as is) did not differ (P>0.05) between diets. Food intake and fecal output (g/d DMB) were greater (P<0.05) when cats consumed the kibble diet. Protein digestibility was higher (P<0.05) when cats were fed the raw meat diet vs. the kibble diet. Nitrogen intake was greater (P<0.05) when cats consumed the kibble diet, and more (P<0.05) nitrogen was present in the feces; however, the percentage of nitrogen retained and nitrogen balance did not differ (P>0.05). Fecal scores, ammonia, SCFA, and BCFA concentrations did not differ (P>0.05) between diets. Fecal butyrate molar ratio was higher (P<0.01) when cats consumed the kibble diet. Blood analyses demonstrated few differences between diets, but alanine aminotransferase activity and bicarbonate were higher (P<0.05) when cats consumed the commercial raw meat diet. Owing to lack of differences, these data indicate that African wildcats can readily utilize a high protein extruded kibble diet, and may be able to replace a commercial raw meat diet.

Evaluation of nutrient digestibility and fecal characteristics of exotic felids fed horse- or beef-based diets: use of the domestic cat as a model for exotic felids.

The objective of this study was to determine the effects of feeding commercially available beef- and horse-based diets on nutrient digestibility and fecal characteristics of large captive exotic felids and domestic cats. Four species of large exotic felids including cheetahs, Malayan tigers, jaguars, and Amur tigers, and domestic cats were utilized in a crossover design. Raw meat diets included a beef-based diet (57% protein; 28% fat) and a horse-based diet (51% protein; 30% fat). All cats were acclimated to the diet for 16 days followed by a 4 day collection period, where total feces, including one fresh sample, were collected. All feces were scored on collection. Intake did not differ due to diet, but fecal output was greater when cats consumed the horse-based diet. Total tract apparent dry matter (DM) digestibility was higher (P<0.05) and organic matter (OM) and crude protein (CP) digestibilities were lower (P<0.05) when cats were fed the beef-based diet compared with the horse-based diet. CP digestibility was similar in domestic cats and cheetahs, and greater (P<0.05) than Amur tigers. Fecal scores were lower and fecal DM was greater (P<0.05) when cats consumed the horse-based diet compared with the beef-based diet. Domestic cats had lower (P<0.05) fecal ammonia concentrations compared with all other species. Fecal ammonia concentrations were lowest (P<0.05) when cats were fed the horse-based diet. Fecal total short-chain fatty acid (SCFA), branched-chain fatty acid (BCFA), and butyrate concentrations were higher (P<0.05) when cats consumed the beef-based diet. Our results suggest that the domestic cat serves as an appropriate model for large exotic felid species, but differences among the species exist. Decreased nutrient digestibility by tigers and jaguars should be considered when developing feeding recommendations for these species based on domestic cat data.

Adipose tissue gene expression profiles of healthy young adult and geriatric dogs.

Obesity is a major problem in today's dog population, with aged animals having an increased susceptibility to obesity-related comorbidities. A molecular approach to studying adipose tissue may enhance our understanding of its role in energy homeostasis and the disease process. Thus, the objective of this study was to use canine microarrays to compare gene expression profiles of adipose tissue from geriatric and young adult dogs. Adipose tissue samples were collected from six geriatric (12 year-old) and six young adult (one-year-old) female beagles after being fed one of two diets (animal protein-based vs. plant protein-based) for 12 months. RNA samples were hybridised to canine microarrays. Statistical analyses indicated that age had the greatest impact on gene expression, with 65 differentially expressed gene transcripts in geriatric dogs. Diet had a minor impact on gene expression, altering the expression of only 19 gene transcripts. In general, adipose tissue of geriatric dogs had increased expression of genes associated with cell cycle and growth, cell development and structure, cellular trafficking and protein processing, immune function, metabolism, and transcription and translation, as compared with that of young adults. Overall, our mRNA data suggest either an increased population of macrophages or increased inflammatory nature of adipocytes in adipose tissue of aged dogs.

In utero and postnatal exposure to a high-protein or high-carbohydrate diet leads to differences in adipose tissue mRNA expression and blood metabolites in kittens.

The objective of the present study was to measure the differences in body composition, adipose tissue gene expression, blood metabolite and hormone concentrations, and insulin sensitivity in kittens exposed to high-protein (HP) or high-carbohydrate (HC) nutrition in utero and through the growth period. Eight dams were randomised onto two test diets, and fed the diets throughout gestation and lactation. Male offspring were evaluated for 9 months. Kittens were weaned at 2 months of age onto the same treatment diet as the dam and were allowed to consume diets ad libitum. The HC diet contained 34.3 % crude protein (CP), 19.2 % fat and 30.8 % digestible carbohydrate, while the HP diet contained 52.9 % CP, 23.5 % fat and 10.8 % digestible carbohydrate. Blood samples were collected at 6 months after birth. Body composition was determined at 2 and 8 months of age and an intravenous glucose tolerance test, neutering and adipose tissue biopsy conducted at 8 months of age. Physical activity was quantified at 6 and 9 months. Energy intake, DM intake and body weight were not different between groups. At 2 months, blood TAG were greater (P < 0.05) in kittens fed the HP diet. At 8 months, blood leptin was higher (P < 0.05) in kittens fed the HC diet, while chemokine receptor 5, hormone-sensitive lipase, uncoupling protein 2, leptin and insulin receptor mRNA were greater (P < 0.05) in kittens fed the HP diet. The present results demonstrate some of the changes in blood metabolites and hormones, physical activity and mRNA abundance that occur with feeding high protein levels to kittens.

Age and diet affect gene expression profile in canine skeletal muscle.

We evaluated gene transcription in canine skeletal muscle (biceps femoris) using microarray analysis to identify effects of age and diet on gene expression. Twelve female beagles were used (six 1-year olds and six 12-year olds) and they were fed one of two experimental diets for 12 months. One diet contained primarily plant-based protein sources (PPB), whereas the second diet contained primarily animal-based protein sources (APB). Affymetrix GeneChip Canine Genome Arrays were used to hybridize extracted RNA. Age had the greatest effect on gene transcription (262 differentially expressed genes), whereas the effect of diet was relatively small (22 differentially expressed genes). Effects of age (regardless of diet) were most notable on genes related to metabolism, cell cycle and cell development, and transcription function. All these genes were predominantly down-regulated in geriatric dogs. Age-affected genes that were differentially expressed on only one of two diets were primarily noted in the PPB diet group (144/165 genes). Again, genes related to cell cycle (22/35) and metabolism (15/19) had predominantly decreased transcription in geriatric dogs, but 6/8 genes related to muscle development had increased expression. Effects of diet on muscle gene expression were mostly noted in geriatric dogs, but no consistent patterns in transcription were observed. The insight these data provide into gene expression profiles of canine skeletal muscle as affected by age, could serve as a foundation for future research pertaining to age-related muscle diseases.

Implications of age and diet on canine cerebral cortex transcription.

Mechanisms contributing to age-related cognitive decline are poorly defined. Thus, we used canine microarrays to compare gene expression profiles of brain tissue from geriatric and young adult dogs. Cerebral cortex samples were collected from six geriatric (12-year old) and six young adult (1-year old) female beagles after being fed one of two diets (animal protein-based versus plant-protein based) for 12 months. RNA samples were hybridized to Affymetrix GeneChip Canine Genome Arrays. Statistical analyses indicated that the age had the greatest impact on gene expression, with 963 transcripts differentially expressed in geriatric dogs. Although not as robust as age, diet affected mRNA abundance of 140 transcripts. As demonstrated in aged rodents and humans, geriatric dogs had increased expression of genes associated with inflammation, stress response, and calcium homeostasis and decreased expression of genes associated with neuropeptide signaling and synaptic transmission. In addition to its existing strengths, availability of gene sequence information and commercial microarrays make the canine a powerful model for studying the effects of aging on cognitive function.

Short-chain fructooligosaccharides influence insulin sensitivity and gene expression of fat tissue in obese dogs.

Dietary fibers may modulate insulin resistance and glucose homeostasis in dogs. Their efficacy is, however, dependent on their origin, physical properties, and fermentability in the large bowel. Eight healthy Beagle dogs were fed a commercial diet at twice their maintenance requirements until they became obese. They were then maintained in the obese state and used in a cross-over design study to evaluate the effects of short-chain fructooligosaccharide (scFOS) supplementation (1% wt:wt dry matter in the diet). The euglycemic hyperinsulinemic clamp technique was performed before and after fattening and at the end of each 6-wk cross-over period. Fat tissue biopsies were taken in food-deprived and postprandial phases to measure mRNA abundance of genes involved with fatty acid, glucose metabolism, or inflammation. Insulin resistance appeared progressively with fattening and the rate of glucose infusion during euglycemic clamp was lower (P < 0.05) at the end of the fattening period (7.39 mg.kg(-1).min(-1)) than at baseline (21.21 mg.kg(-1).min(-1)). In stable obese dogs, scFOS increased (P < 0.05) the rate of glucose infusion compared with control (7.77 vs. 4.72 mg.kg(-1).min(-1)). Plasma insulin and triglyceride concentrations were greater in obese than in lean dogs but were not altered by scFOS. Whereas mRNA was not affected in food-deprived dogs, scFOS increased uncoupling protein 2 (P = 0.05) and tended to increase carnitine palmitoyl transferase 1 adipose mRNA levels during the postprandial period (P = 0.09). Adding 1% scFOS to the diet of obese dogs decreases insulin resistance and appears to modulate the transcription of genes involved in fatty acid or glucose metabolism.

Nutrient digestibility and fecal characteristics are different among captive exotic felids fed a beef-based raw diet.

Nutrient digestibility has not been well characterized in exotic felids. The objective of this experiment was to evaluate differences in nutrient digestibility and fecal characteristics in five large exotic captive felid species, including bobcats, jaguars, cheetahs, Indochinese tigers, and Siberian tigers. All animals were individually housed and adapted to a beef-based raw diet (Nebraska Brand((R)) Special Beef Feline, North Platte, NE) for 16 d. Total fecal collections were conducted from days 17 to 20. Fecal samples were weighed and scored on collection. Diet and fecal samples were evaluated for dry matter, organic matter, protein, fat, and energy to determine total tract digestibility. Fresh fecal samples were collected to determine fecal pH, ammonia, phenol, indole, short-chain fatty acid, and branched-chain fatty acid concentrations. Fecal scores were greater (P<0.01) in Indochinese tigers when compared with all other species, and cheetahs had greater (P<0.01) fecal scores than jaguars and bobcats. Fat digestibility was greater (P<0.01) in Siberian tigers, Indochinese tigers, and bobcats (96%) compared with cheetahs and jaguars (94%). Digestible energy was greater (P<0.05) in bobcats and Indochinese tigers at 93.5 and 92.9%, respectively, compared with cheetahs and jaguars, 91.6%. Fecal pH was greater (P<0.01) in bobcats compared with all other species evaluated. Indole concentrations were greater (P<0.05) in cheetahs and jaguars compared with bobcats and Indochinese tigers. Fecal ammonia concentrations were increased (P<0.05) in cheetahs compared with all other species. The beef-based raw diet was highly digestible; however, differences in fat and digestible energy suggest that species should be considered when determining caloric needs of exotic felids. Zoo Biol 27:126-136, 2008. (c) 2008 Wiley-Liss, Inc.

Fructan supplementation and infection affect food intake, fever, and epithelial sloughing from Salmonella challenge in weanling puppies.

Our objective was to examine the effects of fructan supplementation on the immune response of weanling puppies subjected to bacterial challenge. Previous studies in bacterial challenged neonatal piglets have reported benefits of fructan supplementation. Thirty hound-cross puppies (12 wk of age) were used in a 2 x 3 factorial randomized complete block design. Following a 7-d baseline period, puppies were assigned to diets containing: 1) no prebiotic, 2) 1% short-chain fructooligosaccharides (scFOS), or 3) 1% inulin. After 14 d on treatment diet, dogs received an oral gavage of: 1) Salmonella typhimurium DT104 (5 x 10(8) colony forming units) or 2) 0.9% saline. Food intake, fecal and activity scores, body temperature, body weight, blood chemistry, intestinal nutrient transport, intestinal morphology and pathology, and gut microbiota were measured. Food intake decreased (P < 0.01) and body temperature increased (P < 0.05) in infected puppies. However, the decrease in food intake was less (P < 0.05) in those consuming fructans. Infected puppies consuming fructans also had decreased (P = 0.05) severity of enterocyte sloughing than those fed the control diet. Ileal Na+-dependent glucose transport was decreased (P = 0.02) in infected vs. noninfected puppies consuming CON, whereas no changes occurred in fructan-supplemented animals. Puppies consuming inulin also had increased fecal acetate (P = 0.03) and total short-chain fatty acid (P = 0.06) concentrations than scFOS-fed puppies and controls. Finally, puppies fed inulin had an increase (P = 0.05) in Lactobacillus concentrations compared with scFOS and CON. In summary, fructan supplementation appeared to attenuate some of the negative responses associated with Salmonella challenge and may provide protection against infection in weanling puppies.