Nutritional evaluation of commercial dry dog foods by near infrared reflectance spectroscopy

Near infrared reflectance spectroscopy (NIRS) was used to predict the nutritional value of dog foods sold in Chile. Fifty-nine dry foods for adult and growing dogs were collected, ground and scanned across the visible/NIR range and subsequently analysed for dry matter (DM), crude protein (CP), crude fibre (CF), total fat, linoleic acid, gross energy (GE), estimated metabolizable energy (ME) and several amino acids and minerals. Calibration equations were developed by modified partial least squares regression, and tested by cross-validation. Standard error of cross validation (SE(CV)) and coefficient of determination of cross validation (SE(CV)) were used to select best equations. Equations with good predicting accuracy were obtained for DM, CF, CP, GE and fat. Corresponding values for and SE(CV) were 0.96 and 1.7 g/kg, 0.91 and 3.1 g/kg, 0.99 and 5.0 g/kg, 0.93 and 0.26 MJ/kg, 0.89 and 12.4 g/kg. Several amino acids were also well predicted, such as arginine, leucine, isoleucine, phenylalanine-tyrosine (combined), threonine and valine, with values for and SE(CV) (g/kg) of 0.89 and 0.9, 0.94 and 1.3, 0.91 and 0.5, 0.95 and 0.9, 0.91 and 0.5, 0.93 and 0.5. Intermediate values, appropriate for ranking purposes, were obtained for ME, histidine, lysine and methionine-cysteine. Tryptophan, minerals or linoleic acid were not acceptably predicted, irrespective of the mathematical treatment applied. It is concluded that NIR can be successfully used to predict important nutritional characteristics of commercial dog foods.     

Prediction of digestible protein content of dry extruded dog foods: comparison of methods

The aim of this study was to check the accuracy of laboratory methods to predict the apparent protein digestibility (CPd, %) and digestible protein content (DP, g/kgDM) of dog foods, avoiding the use of experimental animals in digestion trials. Twenty‐eight commercial dry extruded dog foods were tested by three different methodologies: an adaptation of the in vitro incubation method described by Hervera et al. (J Anim Physiol Anim Nutr 2007, 91 : 205) for estimation of digestible energy of commercial dog foods, a modification of the pH drop methodology proposed by Hsu et al. (J Food Sci 1977, 42 : 1269) for protein evaluation of human foods and the Near Infra Red Spectroscopy (NIRS) technology. All the methods assessed revealed very good, similar accuracy in the prediction of DP content either using the in vitro method (r = 0.99; RSD = 6.76; CV = 2.31%), the pH drop method (r = 0.99; RSD = 6.94; CV = 3.02%) or the NIRS (R2 = 0.96; SECV = 10.50) method, although the in vitro digestion method showed the highest accuracy approach of in vivo crude protein apparent digestibility: CPd in vitro (r = 0.81; RSD = 2.01; CV = 2.41%); CPd pH‐drop (r = 0.78; RSD = 2.48; CV = 2.98%) and NIRS (r²cv = 0.53; SECV = 2.37).     

ELISA testing for common food antigens in four dry dog foods used in dietary elimination trials

This study evaluated four over the counter venison dry dog foods available from one on-line retail vendor for potential contamination with common known food allergens: soy, poultry or beef. An amplified, double sandwich type enzyme linked immunosorbent assay (ELISA) test of soy, poultry and beef proteins were performed by an independent accredited food laboratory. The ELISA test for poultry protein was found to be unreliable when testing in dry dog foods because false negatives occurred. ELISA testing of control diets for both soy and beef proteins performed as expected and could be useful in antigen testing in dry dog foods. Three of the four over the counter (OTC) venison canine dry foods with no soy products named in the ingredient list were ELISA positive for soy; additionally one OTC diet tested positive for beef protein with no beef products listed as an ingredient list. One OTC venison diet was not found to be positive for soy, poultry or beef proteins. However, none of the four OTC venison diets could be considered suitable for a diagnostic elimination trial as they all contained common pet food proteins, some of which were readily identifiable on the label and some that were only detected by ELISA. Therefore, if the four OTC venison products selected in this study are representative of OTC products in general, then the use of OTC venison dry dog foods should not be used during elimination trials in suspected food allergy patients.     

Evaluation of storage mite contamination of commercial dry dog food

Storage mites may be considered important allergens in dogs with atopic dermatitis. High sensitization rates to Tyrophagus , Acarus , and Lepidoglyphus species have been reported in atopic dogs, and dry pet food has been suggested as a potential source of storage mite exposure. The aim of the present study was to evaluate commercial dry dog food for contamination with storage mites, and how storage time and conditions could influence the risk of contamination. Ten different premium commercial dry dog foods formulated for skin disorders were selected. Food bags were opened and stored for 6 weeks under two different environmental conditions. At different time points, samples from each bag were collected and analysed by microscopy, guanine test, storage mite-specific traps, and a modified flotation technique.
On opening, two storage mites identified as Acarus siro were isolated from one of the 10 bags by flotation technique, indicating that storage mites can be present in packaged dry dog food bags. After 5 weeks of storage under environmental conditions optimal for mite growth (23.2 ± 2.1 °C and 71 ± 5.6% of relative humidity), mites were detected by microscopic observation in nine of the 10 diets. When mites were identified by the flotation technique, Tyrophagus spp. were found to be the most common contaminating species. These results show that dry dog food can be a suitable substrate for storage mite reproduction, and that environmental and storage conditions may influence food contamination and mite development.     

The effect of ingredients in dry dog foods on the risk of gastric dilatation-volvulus in dogs

Using dry dog food label information, the hypothesis was tested that the risk of gastric dilatation-volvulus (GDV) increases with an increasing number of soy and cereal ingredients and a decreasing number of animal-protein ingredients among the first four ingredients. A nested case-control study was conducted with 85 GDV cases and 194 controls consuming a single brand and variety of dry food. Neither an increasing number of animal-protein ingredients (P=0.79) nor an increasing number of soy and cereal ingredients (P=0.83) among the first four ingredients significantly influenced GDV risk. An unexpected finding was that dry foods containing an oil or fat ingredient (e.g., sunflower oil, animal fat) among the first four ingredients were associated with a significant (P=0.01), 2.4-fold increased risk of GDV. These findings suggest that the feeding of dry dog foods that list oils or fats among the first four label ingredients predispose a high-risk dog to GDV.     

The impact of dietary protein source on observed and predicted metabolizable energy of dry extruded dog foods

Fifty-five observations were used to determine the ME content of 8 foods containing different protein sources. The major protein sources tested included low-oligosaccharide whole soybeans; 2 low-oligosaccharide, low-phytate whole soybeans; 2 conventional soybean meals; low-ash poultry meal; low-oligosaccharide, low-phytate soybean meal; and conventional whole soybeans. The ME content of all foods ranged from 3,463 to 4,233 kcal/kg of DM. The first objective was to utilize the observed ME data and test the accuracy of the modified Atwater equation. In this study, the modified Atwater equation generally underpredicted ME compared with the observed ME (residual mean = 247 kcal/kg). The second objective was to use individual data to develop an equation, based on the chemical composition of the food, to predict the ME content of the foods. A multivariate regression analysis was used to predict ME content based on chemical composition. Five models were fitted to the data. Model 1 included CP, ether extract (EE), and crude fiber (CF). Because the foods varied in protein sources, and the ratio of total AA (TAA) to non-AA (NAA) CP ranged from 3.5:1 to 14.4:1, it was hypothesized that accounting for the proportion of TAA and NAA in CP would improve the fit of the model. Therefore, model 2 included TAA, NAA, EE, and CF. Defining CP in terms of TAA and NAA improved the r2 of the model from 0.46 to 0.79. Subsequently, models 3, 4, and 5 replaced the CF term with ADF, NDF, and hemicellulose (HEM). Model 3 included TAA, NAA, EE, and NDF. Model 4 included TAA, NAA, EE, ADF, and HEM. Model 5 included TAA, NAA, EE, and HEM. Defining dietary fiber in terms of HEM improved the r2 of model 2 from 0.79 to 0.81. Residual analysis suggested that replacing the CF term with HEM (model 5) improved the prediction of ME content. In contrast, defining fiber in terms of NDF (model 3) did not result in an improvement over model 2, whereas the ADF term (model 4) did not (P > 0.34) contribute to the overall model. Fractionating CP into TAA and NAA components further defined the chemical composition of the food. These data suggest that defining protein composition improves the accuracy of predicting the ME content of dog foods.     

Comparison of procedures for assessing adequacy of dog foods.

Dog foods with similar claims for nutritional adequacy were tested by chemical analysis and the American Association of Feed Control Officials' growth trial. All foods tested were similar chemically, however, dogs given one regionally marketed food had lower growth rate and food efficiency as well as suboptimal PCV and hemoglobin values during the growth trial. Pups fed this diet also had clinical signs typical of zinc and copper deficiencies. We concluded that American Association of Feed Control Officials' approved feeding tests provide valid assessment of pet food quality, and procedures involving only chemical analysis or calculated values may not.     

Evaluation of stabilized rice bran as an ingredient in dry extruded dog diets

The objectives of this research were to examine the palatability of stabilized rice bran (SRB) when included in a dry canine diet, and to determine the effects of SRB on food intake, digestion, fecal characteristics, blood lipid characteristics, and selected immune mediators. Experiment 1 tested the palatability of SRB. Diets contained poultry fat in Test 1 and soybean oil in Test 2, in conjunction with either 12% SRB or 12% defatted rice bran (DRB, as-fed basis), and were fed to 20 dogs. Diets contained approximately 32% protein and 22% fat (DM basis). Food intake data were collected and intake ratios calculated (grams of SRB diet consumed divided by total consumed of both diets). Intake ratios were 0.73 for Test 1 (P < 0.01) and 0.61 for Test 2 (P < 0.14) for SRB diets. Diets in Exp. 2 contained 12% SRB or DRB (as-fed basis), and poultry fat, beef tallow, or poultry fat:soybean oil (50:50) as the main fat sources, and were fed to 36 beagles. Diets contained approximately 32% protein and 22% fat (DM basis). The effects of SRB and DRB were determined on food intake, digestibility, fecal characteristics, and blood fatty acid, phospholipid, and eicosanoid concentrations. No differences were noted in food intake, digestibility, or fecal characteristics. Fat sources contributed much more to dietary fat than rice bran source; therefore, fat source profiles overwhelmed the rice bran source contribution. Dogs consuming a DRB diet had lower (P < 0.050) plasma phospholipid total monounsaturated fatty acids compared with those consuming a SRB diet (-1.17 vs. 0.95%, respectively), whereas plasma fatty acid concentrations tended (P < 0.119) to decrease more than with SRB diets. Total concentrations of red blood cell phospholipid SFA tended (P < 0.15) to be greater in dogs consuming a beef tallow-containing diet compared with those consuming a poultry fat or poultry fat:soybean oil diet. Total concentrations of red blood cell phospholipid PUFA and n-6 PUFA tended to be greater (P < 0.097 and P < 0.083, respectively) in dogs consuming a poultry fat-containing diet than in those consuming a beef tallow-containing diet. Statistical differences and tendencies were detected in individual plasma fatty acids and plasma and red blood cell phospholipids due to rice bran source, fat source, and their interaction. Eicosanoid concentrations did not change due to treatment. Stabilized rice bran is a highly palatable ingredient when included in a dry dog diet, and did not elicit an effect on inflammatory immune mediators in healthy dogs.     

Evaluation of microbial contamination and effects of storage in raw meat-based dog foods purchased online

Feeding raw-meat-based diets to companion animals has become a widespread practice, and many owners are now accustomed to buying frozen ingredients online. The goals of this study were to assess the microbiological quality of raw-meat dog foods obtained from specialized websites and to evaluate the effects of storage at different temperatures for a few days. Twenty-nine raw dog food products were processed for quantitative bacteriology (i.e. total viable count, TVC; Escherichia coli; faecal coliforms, FC) and sulphite-reducing clostridia, and analysed for the presence of Salmonella spp., Listeria monocytogenes, Yersinia enterocolitica and Clostridium difficile. Every sample was examined right after the delivery (T0), after 24 to 48 hr and after 72 hr, both at 2°C and 7°C. At T0, the mean score for the TVC was 5.9 × 10⁶ cfu/g (SD = 4.8 × 10⁷ cfu/g), while those for E. coli and FC were 1.1 × 10⁴ cfu/g (SD = 2.5 × 10⁵ cfu/g) and 3.3 × 10³ cfu/g (SD = 6.5 × 10⁴ cfu/g) respectively. The samples stored at 2°C had a significant increase of all parameters (TVC: p < .01; E. coli: p = .03; FC: p = .04) through time. Noteworthy differences between the analyses performed at 2°C and 7°C were found for TVC (p < .01), being the samples considerably more contaminated at higher temperatures. No sample tested positive for Salmonella spp., while L. monocytogenes was isolated from 19 products, Y. enterocolitica from three products and Clostridium perfringens and C. difficile from four and six products respectively. The microbiological quality of raw-meat dog foods sold online appears to be poor, carrying considerable amounts of potentially zoonotic bacteria and reaching greater levels of bacterial contaminations if not kept at proper refrigeration temperatures and fed soon after defrosting.     

Predictive equations of selenium accessibility of dry pet foods

The trace element selenium is essential to both dogs and cats. Dry diets are formulated with a large range of ingredients, which may vary in selenium concentration and accessibility. This paper reports equations to predict the average in vitro selenium accessibility from dry pet foods based on essential dietary nutrient concentrations, including crude protein, amino acids and crude fat. Predictive equations were made using stepwise linear regression for extruded and pelleted diets. The equations can be used to aid diet formulation to optimize selenium accessibility within the diet and to prevent selenium deficiency or toxicity.     

Effect of dry, soft moist, and canned dog foods on postprandial blood glucose and insulin concentrations in healthy dogs

The effect of dry, soft moist, and canned dog foods on immediate postprandial plasma glucose and insulin concentrations was evaluated in clinically normal dogs. Dogs were fed either dry (10 dogs; group I), soft moist (10 dogs; group II), or canned (8 dogs; group III) dog food for 5 consecutive days. On the fifth day, plasma glucose and insulin concentrations were determined in each dog prior to, during, and at 5, 10, 15, 30, 45, 60, 90, 120, 180, and 240 minutes after ingestion of the food. The alterations in plasma glucose concentrations were not significantly different from prefeeding values until 240 and 180 minutes after feeding for groups I and III, respectively. In contrast, the increments in plasma glucose were significantly (P less than 0.01) increased from basal concentrations at 30 and 45 minutes after feeding in group-II dogs. The maximal mean postprandial plasma glucose concentration was significantly (P less than 0.0001) less for group III, compared with concentrations for groups I and II, but there was no significant difference between concentrations for groups I and II. Although a biphasic insulin secretory response was found in all 3 groups of dogs, the patterns of phase-2 insulin secretion and the total amount of insulin secreted during the study were significantly different. There was a rapid increase in the plasma insulin concentration immediately after phase 1 in group II, with maximal plasma insulin concentrations occurring 30 minutes after feeding, followed by a gradual decrease in concentrations throughout the remainder of the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

防暴犬攻击持枪案犯实战技能训练方法初探

在2004年度全警岗位大练兵的热潮中,我们对使用防暴犬攻击制服持枪案犯的实战技能进行了训练研究探索,取得了初步成果,并在第二届全国警犬技术比赛开幕式上进行了汇报演练。现将训练方法介绍如下：     

Identification and concentration of soy phytoestrogens in commercial dog foods

OBJECTIVE: To identify and determine the concentrations of phytoestrogens in commercial dog foods. SAMPLE POPULATION: 24 commercial dog foods, including 12 moist or dry extruded commercial dog foods that contained soybeans or soybean fractions and 12 foods without any soybean-related ingredients listed on the label. PROCEDURE: Foods were analyzed for phytoestrogen content, including 4 isoflavones (genistein, glycitein, daidzein, and biochanin A), 1 coumestan (coumestrol), and 2 lignans (secoisolariciresinol and matairesinol) by use of acid-methanol hydrolysis and high-pressure liquid chromatography with UV-absorbance detection. Phytoestrogens were identified and quantified by reference to authentic standards. RESULTS: Isoflavones, coumestans, and lignans were undetectable in diets that did not list soybean-related ingredients on the label. Only 1 of the 12 diets that included soybean or soybean fractions had undetectable concentrations of phytoestrogens and that product contained soy fiber. The major phytoestrogens were the isoflavones daidzein (24 to 615 microg/g of dry matter) and genistein (4 to 238 microg/g of dry matter). CONCLUSIONS AND CLINICAL RELEVANCE: Soybean and soybean fractions are commonly used ingredients in commercial dog foods. Dietary intake of phytoestrogens may have both beneficial and deleterious health effects. Our results indicated that certain commercial dog foods contain phytoestrogens in amounts that could have biological effects when ingested long-term.