Grain free diets for utility dogs during training work: Evaluation of the nutrient digestibility and faecal characteristics

The effects of torula yeast as a protein source on apparent total tract digestibility, inflammatory markers, and fecal microbiota dysbiosis index in Labrador Retrievers with chronically poor stool quality

This study examined the effects of varying protein sources on apparent total tract digestibility, inflammatory markers, and fecal microbiota in Labrador Retrievers with historically poor stool quality. Thirty dogs (15 male, 15 female; aged 0.93 to 11.7 yr) with stool quality scores ≤2.5 on a 5-point scale (1 representing liquid stool and 5 representing firm stool) were randomly assigned to 1 of 3 nutritionally complete diets with differing protein sources and similar macronutrient profiles: 1) chicken meal (n = 10); 2) 10% brewer's yeast (n = 10); or 3) 10% torula yeast (n = 10). Another 10 dogs (five male, five female) with normal stool quality (scores ranging from 3 to 4) received diet 1 and served as negative control (NC). All dogs were fed diet 1 for 7 days, then provided their assigned treatment diets from days 7 to 37. Daily stool scores and weekly body weights were recorded. On days 7, 21, and 36, blood serum was analyzed for c-reactive protein (CRP), and feces for calgranulin C (S100A12), α1-proteinase inhibitor (α1-PI), calprotectin, and microbiota dysbiosis index. Apparent total tract digestibility was assessed using the indicator method with 2 g titanium dioxide administered via oral capsules. Stool scores were greater in NC (P < 0.01) as designed but not affected by treatment × time interaction (P = 0.64). Body weight was greater (P = 0.01) and CRP lower (P < 0.01) in NC dogs. Dry matter and nitrogen-free extract digestibility did not differ among groups (P ≥ 0.14). Negative controls had greater fat digestibility compared to BY (94.64 ± 1.33% vs. 91.65 ± 1.25%; P = 0.02). The overall effect of treatment was significant for protein digestibility (P = 0.03), but there were no differences in individual post hoc comparisons (P ≥ 0.07). Treatment did not affect S100A12 or α1-PI (P ≥ 0.44). Calprotectin decreased at a greater rate over time in TY (P < 0.01). The dysbiosis index score for BY and TY fluctuated less over time (P = 0.01). Blautia (P = 0.03) and Clostridium hiranonis (P = 0.05) abundances were reduced in BY and TY. Dogs with chronically poor stool quality experienced reduced body weights and increased serum CRP, but TY numerically increased protein digestibility, altered the microbiome, and reduced fecal calprotectin. Torula yeast is a suitable alternative protein source in extruded canine diets, but further research is needed to understand the long-term potential for improving the plane of nutrition and modulating gut health.

Assessment of the content of macronutrients and microbiological safety of dry dog foods

In Europe, there are no legal regulations specifying maximum allowable limits for pathogenic bacteria or fungi and yeasts in dog food. For proximate composition, the European Pet Food Industry Federation (FEDIAF) nutritional guidelines provide minimum recommended levels for protein and fat only, not for other ingredients and no safe maximum levels. Therefore, the aim of this study was to evaluate the microbiological safety of 35 dry dog foods, taking into account the division into foods with grains as the main plant ingredient and those described as grain-free. We assumed that grain-included foods are more susceptible to the presence of the total number of aerobic bacteria. This parameter is an essential, hygienic criterion informing about the microbiological safety of the pet food. It also inform about the microbiological quality of the food ingredients used, the effectiveness of decontamination during the production process, sanitary and hygienic conditions during the acquisition, processing and marketing of pet food and its components. In the case of macronutrients, the results in some cases were multiples of the minimum recommended levels. The most important microorganisms that presence was found in the analyzed dog foods were indicator bacteria (E. coli and coliform bacteria, Clostridium perfringens), whose presence in feed constitutes microbiological contamination. They inform about sanitary and hygienic conditions during the production and storage of the pet food. The current guidelines recommend microbiological testing of food for the presence of Salmonella bacilli as the basic indicator for assessing the sanitary quality. No Salmonella spp. was detected in any of the foods. The remaining analyzed bacteria (Proteus spp., Enterococcus spp., Staphylococcus spp.) as well as molds and yeasts, were present in both grain-included and grain-free foods. The obtained results showed that in terms of microbiological safety, grain-included foods come out worse, because microorganisms were detected more frequently in this type of dry dog food.

Fecal microbiota and inflammatory and antioxidant status of obese and lean dogs, and the effect of caloric restriction

Introduction

Obesity is the most common nutritional disease in dogs, and is generally managed by caloric restriction. Gut microbiota alteration could represent a predisposing factor for obesity development, which has been associated with a low-grade inflammatory condition and an impaired antioxidant status. Besides, weight loss has been shown to influence the gut microbiota composition and reduce the inflammatory response and oxidative stress.

Method

However, these insights in canine obesity have not been fully elucidated. The aim of this study was to assess the differences in serum and inflammatory parameters, antioxidant status, fecal microbiota and bacterial metabolites in 16 obese and 15 lean client-owned dogs and how these parameters in obese may be influenced by caloric restriction. First, for 30 days, all dogs received a high-protein, high-fiber diet in amounts to maintain their body weight; later, obese dogs were fed for 180 days the same diet in restricted amounts to promote weight loss.

Results

Before the introduction of the experimental diet (T0), small differences in fecal microbial populations were detected between obese and lean dogs, but bacterial diversity and main bacterial metabolites did not differ. The fecal Dysbiosis Index (DI) was within the reference range (< 0) in most of dogs of both groups. Compared to lean dogs, obese dogs showed higher serum concentrations of acute-phase proteins, total thyroxine (TT4), and antioxidant capacity. Compared to T0, dietary treatment affected the fecal microbiota of obese dogs, decreasing the abundance of Firmicutes and increasing Bacteroides spp. However, these changes did not significantly affect the DI. The caloric restriction failed to exert significative changes on a large scale on bacterial populations. Consequently, the DI, bacterial diversity indices and metabolites were unaffected in obese dogs. Caloric restriction was not associated with a reduction of inflammatory markers or an improvement of the antioxidant status, while an increase of TT4 has been observed.

Discussion

In summary, the present results underline that canine obesity is associated with chronic inflammation. This study highlights that changes on fecal microbiota of obese dogs induced by the characteristics of the diet should be differentiated from those that are the consequence of the reduced energy intake.

Nutrition of Working Dogs: Feeding for Optimal Performance and Health

Working dogs are athletes, but have a wide variety of work types and durations that impact their dietary needs. Their basic nutritional needs do not change: all dogs need a complete and balanced diet, fed in proper proportions to maintain optimal body condition. However, with increasing muscle work and endurance, the amounts of specific nutrients (particularly the macronutrients, protein, fat, and carbohydrates) must be adjusted. This article provides an overview of the key aspects of working canine nutrition and provides the nutritional science behind the recommendations made.

Evaluation of nutritional value and microbiological safety in commercial dog food

In addition to properly balancing nutritional value in accordance with the needs of a dog, estimating the microbiological quality of dog food is crucial in providing healthy and safe foods. The aim of this study was to examine the quality of dry food for adult dogs, with particular reference to: (1) evaluating the nutritional value and compliance with nutritional guidelines for dogs, (2) comparing the nutritional value of dog foods, with particular emphasis on the division into cereal and cereal-free foods, and (3) evaluating their microbiological safety. All thirty-six evaluated dry dog foods met the minimum European Pet Food Industry FEDIAF requirement for total protein and fat content. The total aerobic microbial count in the analyzed dry dog foods ranged from 2.7 × 10² to above 3.0 × 10⁷ cfu/g. In five (14%) dog foods the presence of staphylococci was detected; however, coagulase positive Staphylococcus (CPS) was not found. Mold presence was reported in one cereal-free dog food and in six cereal foods. In none of the analyzed foods Enterobacteriaceae were found, including coliforms, Escherichia coli and Salmonella spp. Bacteria of the genus Listeria and Clostridium as well as yeasts were also not detected. In conclusion, the evaluated dry dog foods had varied microbiological quality. The detected number of microorganisms may have some implications for long-term consumption of contaminated food. The lack of European Commission standards regarding the permissible amounts of microorganisms in pet food may result in insufficient quality control of these products.

Comparison of digestibility parameters of commercial dry dog foods with different contents

ABSTRACT This study was aimed to evaluate and compare the nutrient digestibility of grain-inclusive and grain-free commercial dry dog foods using the method of total fecal collection and also explore their effects on fecal consistency. 21 different foods, including 14 grain-inclusive (7 grain-chicken meat, 7 grain-lamb meat) and 7 grain-free were investigated. 12 adult Golden retriever dogs (age 3-4 years, body weight=22.5±1.7kg) were divided into 3 groups. The results of digestibility trials indicated that the grain-lamb meat foods showed the highest digestibility of dry matter, organic matter, and crude fiber. Overall, in the grain-inclusive and grain-free group evaluation, grain-inclusive foods showed higher digestibility of crude fibers while grain-free foods had higher ether extract digestibility whereas the differences in the scores of fecal consistencies between the groups were insignificant. Contrary to popular belief, grain-inclusive foods were more digestive than grain-free foods in terms of dry matter and organic matter. There are studies involving starch sources in the dog food formulations, but there is a need to study the digestibility of complete dog food to supply them with adequate nutrients. Also, each diet should be assessed based on its overall nutrient profile and digestibility rather than individual ingredients.

A commercial grain-free diet does not decrease plasma amino acids and taurine status but increases bile acid excretion when fed to Labrador Retrievers

Grain-free diets tend to have greater inclusions of pulses in contrast to grain-based diets. In 2018, the Food and Drug Administration (FDA) released a statement that grain-free diets may be related to the development of canine dilated cardiomyopathy (DCM). However, all dog foods met regulatory minimums for nutrient inclusion recommended by the Association of American Feed Controls Official. In some FDA case reports, but not all, dogs diagnosed with DCM also had low concentrations of plasma or whole blood taurine; thus, we hypothesized that feeding these diets will result in reduced taurine status from baseline measures. The objective of this study was to determine the effects of feeding a grain-free diet to large-breed dogs on taurine status and overall health. Eight Labrador Retrievers (four males and four females; Four Rivers Kennel, MO) were individually housed and fed a commercial complete and balanced grain-free diet (Acana Pork and Squash formula; APS) for 26 wk. Fasted blood samples were collected prior to the start of the trial (baseline; week 0) and at weeks 13 and 26 for analyses of blood chemistry, hematology, plasma amino acids, and whole blood taurine. Urine was collected by free catch at weeks 0 and 26 for taurine and creatinine analyses. Fresh fecal samples were collected at weeks 0 and 26 for bile acid analyses. Data were analyzed using the GLIMMIX procedure with repeated measures in SAS (v. 9.4). Plasma His, Met, Trp, and taurine and whole blood taurine concentrations increased over the course of the study (P < 0.05). Urinary taurine to creatinine ratio was not affected by diet (P > 0.05). Fecal bile acid excretion increased after 26 wk of feeding APS to dogs. Despite the higher fecal excretion of bile acids, plasma and whole blood taurine increased over the 26-wk feeding study. These data suggest that feeding APS, a grain-free diet, over a 26-wk period improved taurine status in Labrador Retrievers and is not the basis for the incidence of DCM for dogs fed APS. Other factors that may contribute to the etiology of DCM should be explored.

Effect of different starch sources in a raw meat-based diet on fecal microbiome in dogs housed in a shelter

A dietary intervention study was assessed to determine if different sources of starch in homemade diets could significantly modify fecal microbiome of dogs. Twenty-seven adult dogs were enrolled and fed a diet based on a mixture of rice and pasta with fresh raw meat (CD). After 90 d, 8 dogs continued to receive CD diet, 10 dogs received a diet made of a raw meat and a complementary food with rice as the main source of starch (B1), and 9 dogs were fed a diet with the same raw meat and a complementary food with potato as the main source of starch (B2). Samples of feces were collected from each dog in the mornings at the beginning of the study and after 15 d and analyzed for pH, ammonia N (N–NH₃) and total N, short chain fatty acids (SCFA) and lactic acid. Relative abundance of fecal microbiota was assessed by sequencing and annotating the V3–V4 regions of the 16S rRNA. Total starch intake was similar between diets but differed in the in vitro rate digestion and in the resistant starch, which was higher in B2 than in B1 and CD diets. Dogs fed B2 diet showed lower (P < 0.05) N–NH₃ and pH but higher (P < 0.05) molar proportion of lactic acid. Linear discriminant analysis of the genera relative abundances indicated a significant (P < 0.01) increase of SMB53 genus at the end of the study in B1 diet and of Megamonas genus in B1 and B2 diets in comparison to CD diet. These results suggest that changes of starch source in a raw meat-based diet have limited effects on fecal microbiome in healthy dogs, but underline a high variability of microbiota among dogs.

Thyroid and Lipid Status in Guide Dogs During Training: Effects of Dietary Protein and Fat Content

Nutrition plays a leading role that most influences thyroid response and energetic metabolism. Aim was to compare the effect of diet on thyroid and lipid status in guide dogs during a 12-weeks training period. Eight Labrador Retrievers were divided into two groups homogeneous for sex, age, body weight, and Body Condition Score (BCS) and fed two commercial diets one, HPF, characterized by low-carbohydrate/high-protein/high-fat (29%:39%:19% as-fed) and the other, LPF, by high-carbohydrate/low-protein/low-fat (50%:24%:12% as-fed) content. The serum thriiodothyronine (T₃), thyroxine (T₄), cholesterol (CHOL), triglycerides (TAGs) and non-esterified fatty acids (NEFA) were determined at Day 0, 28, 56, and 84, before the daily training. Statistical model included the effects of Diet (HPF vs. LPF) and Time (Day 0 to Day 84), and their interaction. In the HPF group, Diet significantly (p < 0.01) increased T₄, CHOL, and TAGs and decreased NEFA. In both groups, Time significantly (p < 0.05) increased T₄ and TAGs, CHOL at Day 28, and NEFA at Day 56. The interaction did not influence serum hormones and lipid pattern. The adjustments in thyroid and lipid responses to moderate exercise in HPF group were driven mainly by the nutrient composition of the diet in relation to the involvement of metabolic homeostasis.