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Global protein shortages and sustainability concerns have increased consumer demand for non-animal-derived protein. Dried whole-cell yeast (Saccharomyces cerevisiae) may be a suitable alternative to rendered protein meals in pet foods. The objective of this study was to investigate the effects of dried yeast in dog and cat foods on indicators that pet parents typically use to evaluate the suitability of a food for their pet. For this evaluation, two dog and two cat dry extruded diets were formulated. For each species, the test diet contained 10% dried yeast (Yeast) and the control diet was devoid of yeast (Control). Palatability, apparent total tract nutrient digestibility, and fecal quality of the foods were assessed in dogs and cats. Urine pH and specific gravity were measured in cats as indicators of urinary tract health. In dogs, the Yeast diet showed equivalent or better palatability compared to the Control diet based on total food consumption (P  = 0.06), average daily consumption (day 1, P  = 0.10; day 2, P  = 0.54), and first choice preference over 2 consecutive days (P  = 0.005). Cats showed a strong preference for the Yeast diet with more than double the consumption during the 2-d test period (P  = 0.001). More cats showed a first-choice preference for the Yeast diet (24 vs. 16), but the difference was not statistically significant (P  = 0.21). There were no significant differences in stool quality or nutrient digestibility when fed Yeast vs. Control diets to the dogs and cats (P  > 0.05). All cats produced urine with pH and specific gravity values within the normal range, though specific gravity was lower in the Control group (P  = 0.003). This study provides support for the acceptability and digestibility of dog and cat diets containing dried yeast as an alternative protein source. [ABSTRACT FROM AUTHOR]

Twelve abomasally cannulated wether lambs were fed isocaloric diets containing 9, 12 or 15% crude protein to determine insulin-like growth factor-I (IGF-I) responses to altered abomasal nitrogen flow and nitrogen status. Lambs were offered 1100 g/d of their respective diets. Voluntary feed consumption was not affected by nitrogen intake. Ruminal and total tract digestibilities of dry matter, organic matter and nitrogen increased linearly (P < 0.05) with increased dietary nitrogen. Abomasal flows of total, bacterial and rumen escape nitrogen increased (linear, P < 0.01), whereas dry matter and organic matter flows decreased (linear, P < 0.01). Total amino acid flow was greater (linear, P < 0.01) in lambs fed additional nitrogen due to increased (linear, P < 0.01) flows of essential and nonessential amino acids. Nitrogen retention and blood urea nitrogen increased linearly (P < 0.01). Serum IGF-I concentrations and relative hybridization intensity of hepatic IGF-I mRNA increased (linear, P < 0.05) as lambs consumed more nitrogen. Serum IGF-I and hepatic IGF-I mRNA were correlated positively (P < 0.05) with nitrogen intake and abomasal flows of nitrogen and various amino acids. These data provide evidence of a relationship between abomasal amino acid flow, as influenced by nitrogen intake, and hepatic gene expression and serum concentrations of IGF-I in growing lambs. INDEXING KEY WORDS: insulin-like growth factor-I; lambs; nitrogen status; gene expression; dietary protein

Increased consumer interest in high-quality and novel protein sources has driven the demand for the inclusion of protein-rich ingredients in companion animal diets. Novel protein concentrates, with protein contents of at least 50%, have been used to satisfy these consumer demands. However, minimal information is available regarding the macronutrient composition and protein quality of these ingredients that is needed for proper formulation of pet foods. Therefore, the objectives of this study were to determine the macronutrient and amino acid compositions, standardized amino acid digestibility according to the precision-fed rooster assay, and protein quality using digestible indispensable amino acid score (DIAAS like) of pea protein (PP), potato protein (POP), faba bean protein (FBP), soy protein concentrate (SPC), and dried yeast (DY). Precision-fed rooster assays were conducted using cecectomized roosters to calculate standardized amino acid digestibility and true metabolizable energy corrected for nitrogen (TMEn). For all five protein concentrates, all essential amino acids were highly digestible (88.0% to 96.3%, dry matter basis) with differences (P < 0.05) in only lysine, methionine, and tryptophan digestibilities. The TMEn values were highest for POP (4.22 kcal/g) and DY (3.61 kcal/g). The DIAAS-like values for adult dogs indicated that methionine was the first-limiting amino acid in all protein concentrates except POP, where the first-limiting amino acid was tryptophan. Using Association of American Feed Control Officials (AAFCO)-recommended values for adult cats, DIAAS-like values for methionine were lowest (P < 0.05) for FBP at 81.5%, with all other amino acids for all protein concentrates over 100%. The National Research Council (NRC)-recommended allowances for adult cats indicated that DIAAS-like methionine values for PP (92.7%) and FBP (73.8%) were significantly lower (P < 0.05) with these being the first-limiting amino acids, with the remaining amino acids above 100% for the other protein concentrates. The protein quality and high essential amino acid digestibility of these protein concentrates indicate that they would be viable protein sources in canine and feline diets. However, additional complementary protein sources should be included to meet the requirements of all essential amino acids. [ABSTRACT FROM AUTHOR]

The gut bacterial population has been demonstrated to influence the physiologic and metabolic functions of the host by modulating energy expenditure and immune response, therefore contributing to the health of the host. However, there is little information regarding the effects of probiotics and postbiotics on canine nutrition. The objective of this study was to evaluate the longitudinal effects of daily supplementation of Bifidobacterium animalis subsp. lactis CECT 8145 and the same strain in a heat-killed presentation (postbiotic) on weight management, fecal fermentative end-product concentration, gut hormones, postprandial glycemic and insulinemic response in overweight dogs. Thirty-six adult dogs were used in a completely randomized, double-blinded, placebo-controlled study, with 12 animals per treatment. Dogs were fed a commercial dry extruded complete and balanced diet twice daily to maintain body weight. Following a 60 d adaptation to the control diet, dogs were fed their respective treatment diets for 90 d. Treatments were provided by ADM Biopolis (Valencia, Spain) and given via gelatin capsules before morning feeding to ensure consumption of the total dose of their placebo, probiotic, or heat-killed probiotic. The treatments supplementation had no detrimental effect on the overall dog's health. Throughout the experimental period, fecal scores did not differ among dogs fed different dietary treatments (P > 0.05). However, fecal pH was significantly lower (P = 0.0049) in the dogs fed the postbiotic (5.8) compared with the group control (6.1). Greater fecal concentration of propionate (P=0.0427) was observed on dogs fed the probiotic and the dogs fed the postbiotic compared with the group control. Pancreatic polypeptide plasma concentration was less (P < 0.05) in the dogs fed the probiotic compared with treatment control. These data suggest that the longitudinal supplementation of this specific strain in the live and heatkilled presentation may interact with gut microbial fermentation and gut hormonal regulation. [ABSTRACT FROM AUTHOR]

Probiotics and heat-killed probiotics (postbiotic) have been linked with enhancement of the intestinal barrier function and mucosal immunity, anti-inflammatory properties, as well as production of fermentative end-products including short-chain fatty acids (SCFA), which may confer benefits to the gut microbiome and health. This study aimed to evaluate the longitudinal effects of daily supplementation of pro- and post-biotics on oxidative stress biomarkers such as malondialdehyde (MDA) and superoxide dismutase (SOD), inflammatory biomarkers from a panel of 19 cytokines and chemokines, the hormone leptin, as well as the fecal metabolites, such as phenol and indole, SCFA, and ammonia, of adult cats. The study was a complete randomized design with 36 cats divided into 3 treatments (n=12/treatment). Animals were fed a standard extruded commercial diet. The treatments used were control diet + placebo (maltodextrin carrier; CON), control diet + Probiotic (Bifidobacterium animalis subsp. Lactis CECT8145; daily dosage: 109CFU/cat; PRO), and control diet + postbiotic (Heat-killed Bifidobacterium animalis subsp. lactis CECT8145; daily dosage: 109CFU/cat; PST). Test articles were supplied by ADM Biopolis (Valencia, Spain). Longitudinal analyses were performed every 30 days for a total of 90 days. No interaction of day by treatment (P >0.05) was observed for any of the variables evaluated. For fecal metabolites, there was a main effect of treatment for butyrate concentration, PST was greater (P< 0.05) than PRO. It was also observed a main effect of treatment for some cytokines and chemokines, cats on CON had reduced (P< 0.05) GM-CSF, KC, and SDF-1, when compared with PST, PRO, and both PST and PRO respectively. Whilst for RANTES and IL-12(p40), cats on CON had greater concentration (P< 0.05) when compared with cats on PST and PRO, and PST, respectively. Overall, the supplementation of the probiotic and postbiotic showed no detrimental effects on oxidative stress and inflammatory biomarkers, and fermentative end-products in adult cats. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effects of dietary mannoheptulose (MH; 2 mg kg−1), a glycolytic inhibitor, on glucose oxidation and biomarkers of energy metabolism in neutered, adult, male Labrador Retriever dogs (N= 6). Fasting and post-prandial respiratory quotient (RQ) and energy expenditure (EE) were determined by indirect calorimetry (d 16). Glucose turnover and oxidation were assessed during fasting and repeated meal feeding using indirect calorimetry and a constant intravenous infusion of U-13C-glucose (d 18). A sample from the biceps femoris was obtained to determine the muscle protein content of adenosine monophosphate-activated protein kinase (AMPK) and acetyl CoA carboxylase (ACC; total and phosphorylated forms; d 21). MH did not affect EE, serum glucose, insulin or free fatty acids or ACC protein content. In fasting, MH significantly increased the fasting RQ (p= 0.01) and glucose oxidation (p= 0.01) and tended to decrease the ratio of phosphorylated to total AMPK protein content (p= 0.16). In contrast, post-prandial glucose oxidation tended to be lower (p= 0.14) in dogs fed MH. These results suggest that MH has differential effects on fasting and post-prandial whole body glucose and fat oxidation. However, further research that uses a greater number of animals and/or higher dose of MH is required. [ABSTRACT FROM PUBLISHER]

The popularity of functional ingredients such as probiotics and postbiotics has increased as pet owners seek ways to improve the health quality and longevity of their pets. Limited research has been conducted regarding the use of probiotics and postbiotics and their effects on canine health. The objective of this study was to evaluate the effects of daily supplementation of Bifidobacterium animalis subsp. lactis CECT 8145, in both live probiotic (PRO) and heat-treated postbiotic (POST) forms, on fecal fermentative end-products and microbiome, insulin sensitivity, serum gut hormones, oxidative stress, inflammatory biomarkers, and white blood cell gene expression of adult dogs. Eighteen adult beagles and 18 adult English pointers were used in a double-blinded placebo controlled parallel group design, with 12 animals per group (6 English pointers and 6 beagles). The study began with a 60 d adaptation period followed by a 90 d period of daily supplementation with either PRO, POST, or placebo (maltodextrin; CON). Longitudinal assessment of body weight (BW), body condition score (BCS), and pelvic circumference (PC) did not differ among dietary supplements (P > 0.05). Throughout the experimental period, fecal scores did not differ (P > 0.05), however, fecal pH was lower (P = 0.0049) in the dogs fed POST compared with CON. A higher fecal concentration of propionate (P = 0.043) was observed in dogs fed PRO and POST when compared with CON. While PRO and POST supplementation was associated with changes in bacterial composition at the family and genus level, the overall richness and diversity of the microbiome was not significantly affected. Functional analysis of the metagenome also suggests that PRO and POST supplementation induced potentially beneficial changes in the abundance of pathways involved in pathogenicity, amino acid biosynthesis and DNA repair. No differences in glycemic or insulinemic responses were observed among the groups (P > 0.05). Dogs supplemented with PRO had a higher (P < 0.05) mean white blood cell leptin relative fold gene expression compared with groups POST and CON. Serum metabolites and complete blood cells counts were within normal ranges and all dogs remained healthy throughout the study. Together, these data suggest that the PRO and POST can safely be supplemented for dogs. Moreover, the results of this study support further investigation of the role of PRO and POST in supporting parameters related to gut health and hormonal regulation., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Tryptophan (Trp) is an indispensable dietary amino acid that supports the modulation of mood and behavior in mammalian species through its role in the serotonergic pathway. This study assessed the behavior patterns of 36 healthy, female adult mixed-breed hound dogs fed a control diet (tryptophan = 0.18% as-fed) or 1 of several experimental diets with graded concentrations of tryptophan (0.05%, 0.1%, and 0.15% of the total diet) supplemented on top of the 0.18% basal level. At baseline, and every 8 weeks throughout the 24-week period, behavioral parameters were evaluated for each dog in response to the approach of an individual familiar to the dogs and another individual who was unfamiliar to the dogs. Differences in behavior scores (activity, P = 0.0197; distance, P = 0.0358; confidence, P < 0.0001; and ear position, P < 0.0001) between the unfamiliar and familiar individuals supported the efficacy of the behavioral ethogram used. No consistent and significant differences in behavior were observed, however, among dogs fed the control diet and those fed an experimental diet with any level of tryptophan supplementation. Future research should consider the tryptophan-to-large-neutral-amino-acid ratio and not just tryptophan concentrations, seek to understand the variation in tryptophan requirements among breeds, and look to utilize additional markers of serotonin status., Competing Interests: Author disclosure: James R. Templeman, John P. Cant, and Vern R. Osborne have no conflicts of interest. Gary M. Davenport and Anna-Kate Shoveller were previously employed by Procter and Gamble — Pet Care and have had financial and personal interest in the company. Gary M. Davenport is now an employee of Archer-Daniel Mills and Anna-Kate Shoveller is employed by the University of Guelph.

There is a growing interest in the use of nutraceuticals for weight management in companion animals. The purpose of this study was to determine the effects of mannoheptulose (MH), a sugar in avocados that inhibits glycolysis, on energy metabolism in adult Beagle dogs. The study was a double-blind, randomized controlled trial where dogs were allocated to a control (CON, n = 10, 10.1 ± 0.4 kg) or MH containing diet (168 mg/kg, n = 10, 10.3 ± 0.4 kg). Blood was collected after an overnight fast and 1 h post-feeding (week 12) to determine serum satiety related hormones and biochemistry. Resting and post-prandial energy expenditure and respiratory quotient were determined by indirect calorimetry (weeks 4 and 8). Physical activity was measured using an accelerometer (weeks 3, 7, 11). Body composition was assessed using dual X-ray absorptiometry (week 12). MH significantly (p < 0.05) increased fasting serum glucagon-like peptide-1 and post-prandial serum ghrelin. MH tended (p < 0.1) to increase fasting serum gastric inhibitory peptide and decrease physical activity. Together, these findings suggest that dietary MH has the ability to promote satiation and lowers daily energy expenditure.

Post-exercise carbohydrate supplementation has been routinely used to enhance glycogen concentrations in skeletal muscle, particularly during multiple-day athletic events. Consumption of protein hydrolysates mixed with carbohydrate supplements during the post-exercise period may increase insulin response and cause glycogen repletion in skeletal muscle. A group of Alaskan sled dogs were selected to examine post-exercise supplementation in a paired crossover study design. The dogs were subjected to the same exercise regimen and provided one of three treatments-water, glucose polymers, or glucose polymers with protein hydrolysates-over a 2-month period. Parameters tested at various post-exercise time points included plasma insulin, glucagon and glucose concentrations, and skeletal muscle glycogen content to gain a better understanding of glucose metabolism and glycogen repletion. The results showed an enhanced insulin, glucose, and glucagon response immediately after supplementation and significantly increased glycogen concentrations in skeletal muscle within 24 hours when dogs received either of the glucose-containing supplements compared with water alone. There were no differences in the plasma parameters or skeletal muscle glycogen stores in dogs provided the glucose polymers alone or the glucose polymers plus protein hydrolysates. Thus, post-exercise carbohydrate supplementation increased muscle glycogen repletion, but inclusion of protein hydrolysates in the supplements provided no additional benefits.

The effects of long-term athletic training are associated with excessive skeletal muscle turnover attributable to increased rates of myofibrillar protein synthesis and proteolysis, which are mechanisms poorly understood in the athletic dog. A physiologic field study using 44 English pointers and Labrador retrievers that had been purposely bred for bird hunting and retrieving was conducted to examine changes in the ubiquitin-proteasome (UP) pathway, which has been implicated in exercise-induced proteolysis. Muscle biopsy samples were collected from all dogs in September (preseason, pretraining) and February (peak season, peak activity). Western blot analysis was used to assess changes in expression of various components of the UP pathway in the biopsy samples. Citrate synthase and glycogen levels were also measured in a subset of these samples. Results across the population indicated pronounced up-regulation of ubiquitinated conjugates and the p31 regulatory capping subunit during the peak hunting period compared with the preseason period. In contrast, the catalytic core of the proteasome (beta-subunits) showed no apparent up-regulation in response to increased physical activity. Increased physical activity during the hunting season was associated with increased muscle glycogen levels and citrate synthase activity in these dogs. Overall, up-regulation of specific components of the UP pathway was an indication that it plays a role in the proteolytic process associated with skeletal muscle turnover during long-term athletic training, as previously believed.