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Using of Pelleted and Extruded Foods in Dog Feeding
Abstract
This study was carried out to determine the effects of pellet and extruded foods on gelatinization, digestibility and faecal quality of dogs.
In study 30 adult male dogs of mixed breed, weighing 15-30 kg, neutered and around 1-3 of age were used. The two tested dog-food
formulations had the same composition, but one was produced in pellet form, while the other was extruded in a private factory. Feeding
experiments were conducted at the Dog Unit of the Veterinary Faculty in Selçuk University. Pelleted and extruded food contained 4.87%
and 17.81% gelatinized starch, respectively (P
... Reference source not found., 9]. By altering temperature and moisture, the starch structure becomes disorganized and the granules begin to swell [10]. Starch gelatinization is reported to generate viscosity due to leaching of the amylose fraction, and allow expansion of kibble due to amylopectin content [10][11][12]. ...
... By altering temperature and moisture, the starch structure becomes disorganized and the granules begin to swell [10]. Starch gelatinization is reported to generate viscosity due to leaching of the amylose fraction, and allow expansion of kibble due to amylopectin content [10][11][12]. Because the crystalline structure of the amylose is disrupted during production, digestive enzymes have greater accessibility to the cellular structure of the starch granule, which may improve digestion [Error! ...
... The process of extrusion results in the gelatinization of starches but may occur at varying temperatures based on other system factors (pressure, temperature, etc.) [6,9]. By altering temperature and moisture, the starch structure becomes disorganized and the granules begin to swell [10]. Starch gelatinization is reported to generate viscosity due to leaching of the amylose fraction, and allow expansion of kibble due to amylopectin content [10][11][12]. ...
Simple Summary
The use of novel ingredients is increasing in popularity within the pet food industry. Products utilizing both grain-free and more traditional ingredient profiles are widely available. Unfortunately, gastrointestinal impacts associated with changes in starch content and gelatinization from different grain or carbohydrate sources are unknown. The purpose of this work was to measure starch content and gelatinization in commercially manufactured dry dog food products and assess differences related to ingredient profile. Gelatinized starch was proportionately lower in products manufactured with traditional ingredients (chicken, chicken by-product meal, meat and bone meal and plant-based ingredients including rice, barley, oats, and corn). Diets manufactured with non-traditional ingredients including alligator, buffalo, venison, kangaroo, squid, quail, rabbit, and salmon along with plant-based ingredients including tapioca, chickpeas, lentils, potato, and pumpkin had higher proportions of starch gelatinized. The degree of gelatinization can impact digestibility in the canine digestive tract and is an important area requiring further investigation.
Abstract
Starch gelatinization in pet food may be affected by moisture, retention time, and ingredients used. Starch gelatinization has been associated with changes in digestibility but is not well studied using non-traditional ingredients in canine diets. The objective of this research was to examine differences in starch content and gelatinization associated with changes in ingredient profile (traditional vs. non-traditional) and nutrient content requirements associated with differing life stages. Traditional diets (n = 10) utilizing protein sources including chicken, chicken by-product meal, meat and bone meal and plant-based ingredients including rice, barley, oats, and corn were examined in comparison with non-traditional diets (n = 10) utilizing protein sources including alligator, buffalo, venison, kangaroo, squid, quail, rabbit, and salmon along with plant-based ingredients including tapioca, chickpeas, lentils, potato, and pumpkin. Total starch and gelatinized starch (as percent of total diet) were measured with variation due to ingredient type assessed using Student’s t-test in SAS 9.4. Significance was set at p < 0.05. Total starch (as a percent of diet) was higher in traditional diets compared to non-traditional diets formulated for maintenance (p < 0.0032) or all life stages (p < 0.0128). However, starch gelatinization as a proportion of total starch was lower in traditional diets formulated for maintenance (p < 0.0165) and all life stages (p < 0.0220). Total starch and gelatinized starch had a strong negative correlation (r = −0.78; p < 0.01) in diets utilizing traditional ingredients. These novel data reveal important differences between starch content and gelatinization and may impact selection of various ingredient types by pet food manufacturers.
... Extrusion process may affect the palatability of the diet by controlling the level of specific mechanical energy (Kvamme and Phillips, 2003) [7] . Fatma et al. (2018) [4] reported that the digestibility of protein had increased in the process of extrusion from 76.05% in the pelleted food to 79.63% in the extruded diet with the same composition ...
... Extrusion process may affect the palatability of the diet by controlling the level of specific mechanical energy (Kvamme and Phillips, 2003) [7] . Fatma et al. (2018) [4] reported that the digestibility of protein had increased in the process of extrusion from 76.05% in the pelleted food to 79.63% in the extruded diet with the same composition ...
The four different dietary formulations viz., Normal diet (T1) based on AAFCO recommendations for an adult dog maintenance diet (2014), high protein high fibre diet (T2), high protein medium fibre diet (T3) and control diet supplemented with choline chloride (T4), were prepared by dry extrusion. The percentage of crude protein and crude fibre of T1, T2, T3 and T4 diet were 15.74 and 4.09; 21.90 and 11.28; 21.73 and 8.23; 15.72 and 3.99, respectively. The gross energy value (kcal/kg) of normal (T1) and choline supplemented diets (T4) were 4448.50 and 4478.50, respectively, whereas T3 and T4 were 3714.50 and 3743.50, respectively. The four therapeutic diets were extruded through BTPL twin screw extruder (Model-TSE 002, Kolkatta, India) with the extruder temperature fixed at 124 ˚C and the prepared food was conveyed through pneumatic conveyer to the drier, where the product was dried at 80 ˚C for two hours. Then, the therapeutic diets were packed in LDPE bags and stored at room temperature (30.16 ± 1.26 ˚C).
... This finding means that the more starch is cooked, the easier it is digested. Milder cooking processes like baking and pelleting of kibbles have been reported to result in less starch gelatinization when comparing the same extruded recipe ( Inal et al. 2018;Gibson and Alavi 2013). Pelleting is not a common process for dog food and pellets have been reported to be less palatable than extruded kibbles ( Inal et al. 2018). ...
... Milder cooking processes like baking and pelleting of kibbles have been reported to result in less starch gelatinization when comparing the same extruded recipe ( Inal et al. 2018;Gibson and Alavi 2013). Pelleting is not a common process for dog food and pellets have been reported to be less palatable than extruded kibbles ( Inal et al. 2018). This is likely because of the lower starch gelatinization and different texture of pellets. ...
Corn is one of the largest cereal crops worldwide and plays an important role in the U.S. economy. The pet food market is growing every year, and although corn is well utilized by dogs, some marketing claims have attributed a negative image to this cereal. Thus, the objective of this work was to review the literature regarding corn and its co-products, as well as describe the processing of these ingredients as they pertain to pet foods. Corn is well digested by both dogs and cats and provides nutrients. The processing of corn generates co-products such as corn gluten meal and distillers dried grains with solubles that retain quality protein, and fibrous components that dilute dietary energy. Further, corn has much functionality in extrusion processing. It may yield resistant starch under certain processing conditions, promoting colonic health. Carotenoids in corn may enhance immune support in companion animals if concentrated. Mycotoxin contamination in grains represent a health hazard but are well controlled by safety measures. Genetically modified (GM) corn is still controversial regarding its long-term potential for mutagenicity or carcinogenicity, thus more long-term studies are needed. In conclusion, the negative perception by some in the pet food market may not be warranted in pet foods using corn and its co-products.
... Extrusion reduces apparent nitrogen digestibility, enhances colonic fermentation-as revealed by a decrease in fecal pH associated to the assumption of extruded food [12]-slightly increases dry and organic matter digestibility likely due to the increase in starch digestibility, and increases ether extract digestibility [13]. From a quality control perspective, the industry is interested in the ratio between gelatinized and total starch, which indirectly expresses its availability. ...
... The oligosaccharides formed were treated with purified amyloglucosidase to obtain the glucose. Even if quantified damaged starch does not completely correspond to gelatinized starch, considering the extrusion process conditions, we assume that all the damaged starch in the matrix undergo gelatinization, and thus, in this case, the two parameters present comparable values [13,25]. The fiber fractions were also analyzed according to official methods [26]: NDF, method 2002.04, and ADF and ADL, method 973.18. ...
Simple Summary
Starch is a non-fibrous carbohydrate that represents an important percentage of pet food composition. The degree of its gelatinization, due to the cooking process, can be a useful indicator of starch digestibility in the diet. Moreover, fiber fractions are important for animals’ health and nutritional status, so pet food industry is interested in the development of an easy and cost-effective method to measure these parameters. Results of this study revealed the applicability of visible/near-infrared spectroscopy to predict total and gelatinized starch, neutral detergent fiber, acid detergent fiber, and acid detergent lignin in pet food. On the other hand, near-infrared transmittance technology showed a scarce accuracy. The developed prediction models for total and gelatinized starch and fiber fractions using visible/near-infrared spectroscopy could be applied during the manufacturing process to perform quality controls.
Abstract
This study aimed to assess the feasibility of visible/near-infrared reflectance (Vis-NIR) and near-infrared transmittance (NIT) spectroscopy to predict total and gelatinized starch and fiber fractions in extruded dry dog food. Reference laboratory analyses were performed on 81 samples, and the spectrum of each ground sample was obtained through Vis-NIR and NIT spectrometers. Prediction equations for each instrument were developed by modified partial least squares regressions and validated by cross- (CrV) and external validation (ExV) procedures. All studied traits were better predicted by Vis-NIR than NIT spectroscopy. With Vis-NIR, excellent prediction models were obtained for total starch (residual predictive deviation; RPDCrV = 6.33; RPDExV = 4.43), gelatinized starch (RPDCrV = 4.62; RPDExV = 4.36), neutral detergent fiber (NDF; RPDCrV = 3.93; RPDExV = 4.31), and acid detergent fiber (ADF; RPDCrV = 5.80; RPDExV = 5.67). With NIT, RPDCrV ranged from 1.75 (ADF) to 2.61 (acid detergent lignin, ADL) and RPDExV from 1.71 (ADL) to 2.16 (total starch). In conclusion, results of the present study demonstrated the feasibility of at-line Vis-NIR spectroscopy in predicting total and gelatinized starch, NDF, and ADF, with lower accuracy for ADL, whereas results do not support the applicability of NIT spectroscopy to predict those traits.
... The grains in the pressed food likely were less digestible, thus increasing fecal bacterial protein and lowering apparent protein digestion. More generally, the opposite outcomes of the two digestibility studies (3,4) suggest that interactions between ingredient composition and kibble-production method can affect apparent protein digestion. ...
... The pressed and extruded foods with identical ingredient composition were subjected to a two-bowl preference test in 30 dogs (4). For the pressed versus extruded food, the intake ratio was 34:66, indicating that the dogs preferred the extruded food. ...
The top-selling dry dog foods are extruded kibbles, having an airy and crunchy texture and divergent shapes. Pressed food, or compact, rod-like pellets with smooth surface, has filled a niche in the market over the past half century. The product is now frequently touted as cold-pressed. That marketing phrase attempts to differentiate pressed from extruded food. It is claimed that cold pressing, by avoiding high temperature, preserves natural flavors and essential nutrients (Note 1). Maximum temperature during the processing stage is lower for pressed than extruded food, but both foods generally contain heat-treated animal meal as ingredient. Pressed unlike most extruded kibbles can also contain pre-cooked starch sources. The ingredient statements of some cold-pressed foods list pre-cooked grains, potatoes or peas (Note 2). It could be suggested that the use of pre-cooked starch sources weakens "cold pressed" as advertising slogan. With regard to grains as ingredients, there are pressed foods labeled either grain-free or wheat-free. Other products, according to their ingredient lists, do contain wheat or have rice as the sole type of grain. Quite some pressed foods claim high digestibility as based on their gentle way of production. Some pressed-food makers assert that their products reduce the risk of bloated and twisted stomach in dogs, but such link is unsubstantiated (Note 3). The high-digestibility claim for pressed food may be interpreted as higher net digestion compared to extruded food, due to the difference in production. That inference can only be evaluated by digestion tests with dogs fed the same ingredient mixture, but either pressed or extruded. Two published studies have done just that, but the outcomes for net protein digestibility were opposite. Thus, ingredient mixture and processing may affect one another. A high-digestibility claim for any dog food should be backed by a digestion test. Composition Out of 15 differently branded, complete pressed foods for adult dogs (Note 4), 11 products are presented as cold-pressed. Four and three foods are labeled grain-free and wheat-free. The ingredient lists of four foods declare wheat, whereas three foods contain rice as the sole source of grain. One product uses "low grain" as catch words. The energy composition (% of total dietary metabolizable energy) is as follows: protein, 29/25-39 (mean, n=15/range), fat, 26/20-37, carbohydrates, 45/33-52. The shape of the food pellets mostly is cylindrical (Note 5). Petfood can be evaluated by using its ingredient and analysis statements (1, 2). For pet owners with preferences or dislikes for food items, the ingredient list is helpful. The analysis panel provides limited information. On the basis of its label, complete petfood can be disqualified, but not approved unconditionally. The food labels of non-disqualified, complete pressed and extruded foods do not allow further (comparing and contrasting) nutritional validation. Only (comparative) feeding trials with dogs can do so.
... Of these grains, rice is the most preferred for dog foods due to its high digestibility, low fibre content and hypoallergenic properties. Use of rice does not cause any problems related to digestibility, stool consistency or preference [6] . Whole grains also contribute important nutrients, such as vitamins, minerals and essential fatty acids, in pet foods. ...
This study aimed to compare nutrient digestibility, preference rate, eff ects on stool and cost of grain-inclusive and grain-free dry dog
foods. Two dry dog foods with and without grain formulated with poultry meal, barley, rice, corn, peas, carrot, potato flour, whey, fat, vitamin and mineral sources were manufactured. Twelve adult Golden Retriever dogs (age 3-4 years, body weight = 22.5±1.7 kg) were divided into two groups for the digestibility trial. A total of 20 Golden Retriever and Kangal (age 4-5 years, body weight = 35.5±1.9 kg) breed dogs were used for a two-pan preference test. Crude fibre digestibility of grain-free food was significantly lower (P<0.05). There was no diff erence in other nutrient digestibility in foods as determined by total faecal collection method. Presence of grains in food improved the consistency and dry matter of stool(P<0.05). Dogs preferred grain-free food (55.88%) to grain-inclusive food (44.12%) (P<0.05). The manufacturing cost of grain-free food was found to be about three times higher than grain food. The benefits of grain-free dog diets are debated. Th e eff ects of grain and grain-free foods on digestibility, stool parameters and canine health should be demonstrated by further studies. Cost must be calculated to produce reliable and suitable quality dog food with diff erent ingredients. Palatability and intake levels, which are among the most important criteria in dog nutrition, should be determined by preference tests.
Keywords: Digestibility level, Faecal consistency, Grain free dog food, Grain inclusive dog food, Preference test
... The protein content is certainly a key ingredient of the final product for pets; in fact, the composition of AAs and the bioavailability of proteins define an important nutritional value of the final product [22,35], but it can be altered by production processes [22,29,32,36]. As far as the proteins are concerned, during the extrusion treatment, high temperatures can alter their structure; however, this event is not exclusively negative because slight protein denaturation can favor their subsequent digestion by the body and therefore improve their digestibility [22,36,37]. ...
Simple Summary
The majority of pet food currently on the market is represented by dry food thanks to its practicality and long shelf life. Dry pet food production consists of several processes that can have different effects on nutrient bioavailability and digestibility. The aim of this study was to analyze the nutritional quality of three different chicken-based formulations, consisting of fresh meats, meat meals, or a mix of these two from a protein, lipid, and in vitro digestibility point of view. The results show that the fresh chicken-meat-based formulation appears to be the preferable choice when proteins, lipids, and in vitro digestibility are taken into account. Moreover, the soluble protein content estimated by the Bradford assay is found to correlate well with the total protein content and in vitro digestibility.
Abstract
Dry pet food, made of fresh meats and especially meat meals, represents one of the main types of complete food available on the market by virtue of its practicality and long shelf life. The kibble production process includes mixed thermal and mechanical treatments that help to improve the palatability and durability of the final product but may have undesirable effects on nutrient bioavailability and digestibility. An analysis of the protein and lipid content of different dry pet food formulations, together with an in vitro digestibility analysis, can reveal which formulation can provide a more nourishing diet for pets. In this study, a quantitative and qualitative analysis was performed on three different formulations of chicken-based dry pet food, consisting of fresh meats, meat meals, or a mix of these two. The soluble protein concentration was determined by the Bradford assay, while the crude protein content was assessed through the Kjeldahl method. Quadrupole time-of-flight liquid chromatography/mass spectrometry (Q-TOF LC/MS) was used to analyze the amino acid (AA) and lipid compositions. Finally, a gastric and small intestinal digestion simulation was used to determine the in vitro digestibility. The results show that dry pet food consisting only of chicken fresh meats has the highest content of soluble protein; it also contains more Essential AAs, Branched-Chain AAs, and Taurine, as well as a greater quantity of monounsaturated and polyunsaturated fatty acids. In addition, its in vitro digestibility was the highest, exceeding 90% of its dry weight, in agreement with the soluble protein content. These findings thus make the fresh-meat-based formulation a preferable choice as dry pet food.
... Gelatinized starch was quantified as described byİnal et al. [26], using a Starch damage assay kit (Megazyme Intl. Ireland Ltd., Co. Wicklow, Ireland) that follows the method 76-31.01 of the American Association of Cereal Chemists. ...
Simple Summary
The pet food industry is interested in performing fast analyses to control the nutritional quality of their products. Despite having some limitations related to the need to modify the production process or to have a laboratory to prepare the samples for analysis through desktop instruments, near-infrared spectroscopy is one of the most used technologies for inexpensive analysis of foodstuffs. Thus, the miniaturization of infrared devices allows a wider industrial applicability of this technique. Information on the use of miniaturized infrared tools in the pet food sector is currently very limited, and the present research is the first attempt to predict the total and gelatinized starch, insoluble fibrous fractions, and mineral content of ground and intact dry pet food using the handheld NIR scanner SCiO™. Results from the current study revealed no significant differences in the predictive ability of the instrument using both ground and intact samples. The instrument offers a potential for screening purposes of both total and gelatinized starch, revealing the potential to monitor their content and ratio in commercial dog food on a large scale. Improvements such as widening the wavelength range is expected to increase prediction models’ accuracy.
Abstract
The aim of the present study was to investigate the ability of a handheld near-infrared spectrometer to predict total and gelatinized starch, insoluble fibrous fractions, and mineral content in extruded dry dog food. Intact and ground samples were compared to determine if the homogenization could improve the prediction performance of the instrument. Reference analyses were performed on 81 samples for starch and 99 for neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and minerals, and reflectance infrared spectra (740 to 1070 nm) were recorded with a SCiO™ near-infrared (NIR) spectrometer. Prediction models were developed using modified partial least squares regression and both internal (leave-one-out cross-validation) and external validation. The best prediction models in cross-validation using ground samples were obtained for gelatinized starch (residual predictive deviation, RPD = 2.54) and total starch (RPD = 2.33), and S (RPD = 1.92), while the best using intact samples were obtained for gelatinized starch (RPD = 2.45), total starch (RPD = 2.08), and K (RPD = 1.98). Through external validation, the best statistics were obtained for gelatinized starch, with an RPD of 2.55 and 2.03 in ground and intact samples, respectively. Overall, there was no difference in prediction models accuracy using ground or intact samples. In conclusion, the miniaturized NIR instrument offers the potential for screening purposes only for total and gelatinized starch, S, and K, whereas the results do not support its applicability for the other traits.
The aim of current study was to determine in vitro digestibility, some microbiological properties and shelf life of fermented sucuk foods consisting mixture of animal and vegetable natural goods produced for dogs. Grain-inclusive and grain-free formulations were prepared. Grain-inclusive group was subgrouped as cooked and uncooked grain. In vitro digestibility and chemical composition of 3 groups of sucuk foods were determined at 0, 1, 3, and 6 months after production. Microbiological characteristics (Aerobic colony number, E.coli, coagulase positive Staphylococcus, coliform bacteria, yeast mold, Salmonella spp.), pH, thiobarbituric acid reactive substances(TBARS) and lactic acid levels of sucuks stored in refrigerator(+4°C) were determined at the end of 1, 3, and 6-months of storage. In terms of nutrients, there were differences in storage times between groups and within groups(P
Objective:This study was aimed to investigate the effects of balanced powdered food prepared at different cooking times on preference rate, digestibility and stool quality in dogs.
Methods:Sixteen adult Golden Retriever dogs (3-4 years old) were used. Food mixed with water and cooked daily. The first group (n=5) was given food cooked for 15min, the other (n=5) for 30min. Determination of digestibility by acid insoluble ash method was carried out for 9 days (5d acclimatization, 4d stool collection). Stool scoring was performed by 4 different researchers before collection. Dry matter contents were determined by taking samples from the feces of dogs. Two-pan preference test was also performed. This test was carried out for 12 days and 16 dogs were used. Preference rates were determined by giving the foods at the same time.
Results:Dry matter digestibility of the groups consuming powdered foods cooked for 15min and 30min were 74.12% and 77.96% respectively; organic matter digestibilities were 79.23% and 83.49% respectively (p> 0.05). Food cooked for 15min was preferred 51%, and other one was preferred as 49% (p> 0.05). The stool consistency score and stool dry matter of the dog group that consumed the food cooked for 15min were 3.97 and 36.52% respectively; In the group that consumed the food cooked for 30min were 4.07 and 38.84% respectively (p> 0.05).
Conclusion:Cooking time of 15 minutes, which has a significant effect on digestibility parameters in dogs, is sufficient for the food used in this study.
This study evaluated the effects of inclusion of Yucca schidigera extract (YSE) in two diets with different levels of crude protein (CP) for dogs on facal odour, nutrient digestibility, ammonia concentration in feces and hematological and serum biochemical profiles. Twenty adults Beagles were used, distributed in a randomized block design in a 2 × 4 factorial design (two diets, 25% and 34% CP, and four YSE levels: 0, 250, 500 and 750 mg/kg) with five replicates, obtained during two experimental periods. The fecal odour reduced (P < 0.05) when 500 mg/kg of YSE was used in diets with higher CP. The inclusion of YSE reduced (P < 0.05) fecal ammonia, and the inclusion of 250 and 500 mg/kg YSE reduced intestinal gas. The inclusion of 750 mg/kg YSE increased the mean corpuscular hemoglobin (MCH), alanine aminotransferase (ALT) activity and tended to increase the serum cholesterol concentration, regardless of the protein level of the diets. There was no effect on the digestibility of nutrients, fecal consistency, nitrogen balance and thickness of the intestinal wall. The inclusion of 500 mg/kg YSE is effective in reducing fecal odour in dogs receiving diets with 34% of CP. Regardless of the protein content, YSE reduces fecal ammonia, but may cause adverse effects if included at higher doses.
Extrusion cooking is commonly used to produce dry pet foods. As a process involving heat treatment, extrusion cooking can have both beneficial and detrimental effects on the nutritional quality of the product. Desirable effects of extrusion comprise increase in palatability, destruction of undesirable nutritionally active factors and improvement in digestibility and utilisation of proteins and starch. Undesirable effects of extrusion include reduction of protein quality due to e.g. the Maillard reaction, decrease in palatability and loss of heat-labile vitamins. Effects of extrusion processing on the nutritional values of feeds for livestock have been well documented. Literature results concerning effects of extrusion on dry pet foods, however, are scarce. The present review discusses the results of studies investigating the impact of extrusion cooking on the nutritional quality of dry pet foods. (c) 2008 Society of Chemical Industry.
Two factorial experiments (4 temperatures × 2 durations) were carried out to test the effect of drying variables on nutritional and physical quality indicators of extruded canine diets produced using a 4 and 8 mm die (kibble size). The diet was extruded using a single screw extruder at 130 °C and 300 g moisture/kg. The drying temperatures used were 80, 120, 160 and 200 °C and each diet was dried to 90 or 60 g moisture/kg diet (drying duration). Drying of the diets was conducted in draught-forced ovens and each sample was analysed for dry matter, nitrogen, amino acids (including reactive lysine) and fatty acid content. Hardness and specific density of the tested diets were not affected by drying temperature or time. Kibble durability was affected (P<0.05) by drying temperature: the highest temperature (200 °C) resulted in a decreased durability compared to 80 °C. The drying time had no effects on the level of individual or total amino acids or on the proportion of reactive lysine. In 4 mm kibbles, drying temperature of 200 °C lowered (P<0.05) only proline, total lysine and reactive lysine concentrations: the reactive to total lysine ratio in kibbles dried at 120 °C was higher than that of kibbles dried at 200 °C. Drying temperature of 200 °C decreased the concentration of linolenic and linoleic acid and increased that of oleic acid (P<0.05), a finding that might be indicative for lipid oxidation of 4 mm kibbles during the drying process. In 8 mm kibbles, only reactive lysine concentrations were significantly lower with a concomitant decrease of the kibble durability (P<0.05). Drying of pet foods at high temperatures (160–180 °C) can significantly reduce nutrients or nutrient reactivity.
The number of complete dog foods on the market aim to meet the nutritional needs of the animal and the physiological stage, as the changes that may occur in the use of nutrients. In order to compare the apparent digestibility coefficients (ADC) and stool characteristics of an extruded dry food for adult dogs and puppies, were used 12 beagle dogs, six adults, five, and six puppies, five-six months, kept in metabolic cages and distributed in a completely randomized design. The animals were fed twice a day with a dry extruded complete food for puppies, for an adjustment period of five days followed by five days of total collection of feces. The only difference to the CDA ether extract in acid hydrolysis was higher for babies - 95.3 vs. 89.5%. As for the characteristics of the stool, the pups had a worse score fecal, feces due to have been more moist, and dry stool higher pH and higher content of ammonia, resulting in worse quality. It is concluded that infant 5-6 months of age have a higher digestibility of fat when compared to adult dogs, but defecate stool fecal worst score.
Because animal studies are labor intensive, predictive equations are used extensively for calculating metabolizable energy (ME) concentrations of dog and cat pet foods. The objective of this retrospective review of digestibility studies, which were conducted over a 7-year period and based upon Association of American Feed Control Officials (AAFCO) feeding protocols, was to compare the accuracy and precision of equations developed from these animal feeding studies to commonly used predictive equations. Feeding studies in dogs and cats (331 and 227 studies, respectively) showed that equations using modified Atwater factors accurately predict ME concentrations in dog and cat pet foods (r(2) = 0.97 and 0.98, respectively). The National Research Council (NRC) equations also accurately predicted ME concentrations in pet foods (r(2) = 0.97 for dog and cat foods). For dogs, these equations resulted in an average estimate of ME within 0.16% and 2.24% of the actual ME measured (equations using modified Atwater factors and NRC equations, respectively); for cats these equations resulted in an average estimate of ME within 1.57% and 1.80% of the actual ME measured. However, better predictions of dietary ME in dog and cat pet foods were achieved using equations based on analysis of gross energy (GE) and new factors for moisture, protein, fat and fiber. When this was done there was less than 0.01% difference between the measured ME and the average predicted ME (r(2) = 0.99 and 1.00 in dogs and cats, respectively) whereas the absolute value of the difference between measured and predicted was reduced by approximately 50% in dogs and 60% in cats. Stool quality, which was measured by stool score, was influenced positively when dietary protein digestibility was high and fiber digestibility was low. In conclusion, using GE improves predictive equations for ME content of dog and cat pet foods. Nondigestible protein and fiber content of diets predicts stool quality.
The result of years of experience by experts in extrusion technology, Extruders in Food Applications brings together practical experience and in-depth knowledge of extrusion cooking technology. This concise reference summarizes basic considerations for the application of extrusion technology to food industry processes and focuses on the various types of extruders available for a growing number of food applications. Chapters compare and describe the different types of extruders and their functions, including characteristics, advantages and disadvantages, and applications, providing a wealth of information about dry extruders, interrupted flight extruder-expanders, and single screw and twin screw extruders. The effects of preconditioning on the raw material and of extrusion on the nutrients of products are covered as well. This book is a valuable source for the technical and practical application of extrusion and will be useful for the selection of the proper equipment for this technology.
Seven adult mixed breed female dogs (17.4±2.9kg) surgically fitted with ileal T-cannulas were used in a 4×7 incomplete Latin square design experiment to evaluate oligosaccharide supplementation on dry matter (DM), nitrogen (N), ammonia, volatile fatty acid (VFA), bacteria, blood glucose concentrations, ileal pH, and fecal consistency. Fructooligosaccharide (FOS), mannanoligosaccharide (MOS), and xylooligosaccharide (XOS) were added at 5g/kg of diet DM. There were no differences in DM digestibility, diet or fecal N, N digestibility, ileal or fecal ammonia, fecal consistency, ileal bacteria colony forming units, blood glucose, or ileal pH. Ileal butyrate proportion tended to be greater (P=0.07) in the control diet (0.076 of total VFA) compared with the oligosaccharide supplemented diets and lower (P=0.07) for the MOS diet compared with the FOS and XOS diets. Ileal propionate tended to be higher (P=0.09) in MOS (0.198 of total VFA) than FOS and XOS. Fecal bifidobacteria numbers were unaffected by dietary treatment. Fecal Clostridium perfringens tended to be lower (P=0.09) in MOS when compared to FOS and XOS. Oligosaccharides had relatively minor effects on bacterial growth in the large intestine and VFA proportions in the small intestine of the canine. For oligosaccharide feeding to cause microbial changes in the canine greater amounts of oligosaccharide may be required, or it may require application in select dietary situations.
Procedures for the measurement of starch, starch damage (gelatinised starch), resistant starch and the amylose/amylopectin content of starch, β-glucan, fructan, glucomannan and galactosyl-sucrose oligosaccharides (raffinose, stachyose and verbascose) in plant material, animal feeds and foods are described. Most of these methods have been successfully subjected to interlaboratory evaluation. All methods are based on the use of enzymes either purified by conventional chromatography or produced using molecular biology techniques. Such methods allow specific, accurate and reliable quantification of a particular component. Problems in calculating the actual weight of galactosyl-sucrose oligosaccharides in test samples are discussed in detail. Copyright © 2006 Society of Chemical Industry
Extrusion cooking, as a multi-step, multi-functional and thermal/mechanical process, has permitted a large number of food applications. Effects of extrusion cooking on nutritional quality are ambiguous. Beneficial effects include destruction of antinutritional factors, gelatinisation of starch, increased soluble dietary fibre and reduction of lipid oxidation. On the other hand, Maillard reactions between protein and sugars reduce the nutritional value of the protein, depending on the raw material types, their composition and process conditions. Heat-labile vitamins may be lost to varying extents. Changes in proteins and amino acid profile, carbohydrates, dietary fibre, vitamins, mineral content and some non-nutrient healthful components of food may be either beneficial or deleterious. The present paper reviews the mechanisms underlying these changes, as well as the influence of process variables and feed characteristics. Mild extrusion conditions (high moisture content, low residence time, low temperature) improve the nutritional quality, while high extrusion temperatures (200 °C), low moisture contents (<15%) and/or improper formulation (e.g. presence of high-reactive sugars) can impair nutritional quality adversely. To obtain a nutritionally balanced extruded product, careful control of process parameters is essential.
Digestibility, fecal characteristics, and levels of glucose and urea in the plasma were determined in 8 dogs that received 2 different dog foods once or 3 times daily. One dog food (A) was 5 times more expensive than the other (B). Fecal pH and consistency, digestibility of dry matter (DM), organic matter (OM), crude protein (CP), and crude fiber (CF) were determined. Blood samples were taken from 30 min before to 60 min after a meal. Digestibilities of DM, OM, and CP, and fecal consistency were higher, and daily fecal excretion and fecal pH were lower when dogs were fed food A (P < 0.001). The feeding schedule had no effect on plasma glucose and urea. Neither feeding X frequency nor food 3 frequency interactions was significant for the parameters studied.
A 3 × 2 × 2 factorial trial was designed to investigate the effect of different extrusion conditions and product parameters on the nutritional quality as determined by a number of in vitro measurements (e.g. reactive lysine, and starch gelatinization degree) as well as physical quality of the kibble (durability and hardness) of a canine diet. The parameters investigated were mass temperature (110, 130 or 150 °C), moisture content (200 or 300 g/kg) of the diets prior to extrusion and number of times (once or twice) extruded. Total lysine and other amino acids were unaffected by the extrusion conditions employed. Extrusion conditions had a clear effect on the reactive lysine content with the ratio of reactive to total lysine increasing from 0.71 to 0.80 and higher as a result of extrusion and temperature. After a second extrusion, a decrease was observed from a ratio reaching 1.0 to about 0.9. Initial moisture content affected lysine reactivity. Protein digestibility as measured in vitro was not affected by different extruding conditions. There were no obvious differences in protein dispersibility index (PDI) of all the extrudates. In vitro glucose digestibility coefficients as well as starch gelatinization degree (SGD) showed a tendency to increase with an increase in each individual parameter tested. The increase in temperature from 110 to 150 °C as well as extrusion for a second time decreased kibble durability while increasing moisture content increased durability. Optimisation of extrusion conditions during commercial pet food production should include measurement of the reactive to total lysine ratio
Barley flour and barley flour-pomace (tomato, grape) blends were extruded through a co-rotating twin-screw extruder. The aim of the present study was to investigate the effects of die temperature, screw speed, and pomace level on water absorption index (WAI), water solubility index (WSI), degree of starch gelatinization, and in vitro starch digestibility using a response surface methodology. The selected extrudate samples were examined further using differential scanning calorimetry (DSC) and polarized light microscopy, respectively. The WAI of barley-pomace extrudates was affected by increasing pomace level. Temperature had significant effect on all types of extrudate but screw speed had significant linear effect only on barley and barley-grape pomace extrudates on degree of starch gelatinization. Although no gelatinization peak was detected, an endotherm was observed on all selected extrudates. In general, extrusion cooking significantly increased in vitro starch digestibility of extrudates. However, increasing level of both tomato and grape pomace led to reduction in starch digestibility.
Approximately 25 to 40% of the DM in premium dog diets is animal by-product. However, limited information is available regarding the compo- sition and digestibility of these by-products, especially small intestinal digestibility. The effects of raw and rendered animal by-products incorporated into dog diets on nutrient digestion at the ileum and in the total tract were studied in this experiment. Diets fed contained various animal by-products including a rendered beef meat and bone meal (RMBM); fresh beef (FB); poultry by-product meal (PBPM); fresh poultry (FP); a plant-based control protein source, defatted soy flour (DS); and an animal-based control protein source, dehydrated whole egg (WE). The diets were extruded and kibbled. By-products varied widely in concentrations of OM, CP, amino acids, and fat. Nutrient intakes were numerically higher for FB than for all other treatments. All nutrient intakes were higher ( P < .03) for the FB treatment than for the RMBM treatment. Digestibilities of DM, OM, CP, fat, and GE at the ileum were higher ( P < .06) when dogs were fed diets containing FP than when fed diets containing PBPM. Amino acids were highly digestible at the ileum; however, digestibilities of all amino acids except cystine were higher ( P < .04) for the diets incorporating FP vs PBPM. Total tract digestion was different among treatments for DM ( P < .02), OM ( P < .01), and GE ( P < .02), and diets containing animal by-products were similar in total tract digestibility, greater than the DS control, and lower than the WE control. Rendering of poultry, but not beef, seemed to have a slight negative influence on small intestinal, but not total tract, digestibility by dogs.
An experiment was conducted to determine the effects of extrusion conditions on chemical composition and in vitro hydrolytic and fermentative digestion of barley grits, cornmeal, oat bran, soybean flour, soybean hulls, and wheat bran. Extrusion conditions altered crude protein, fiber, and starch concentrations of ingredients. Organic matter disappearance (OMD) increased for extruded versus unprocessed samples of barley grits, cornmeal, and soybean flour that had been hydrolytically digested. After 8 h of fermentative digestion, OMD decreased as extrusion conditions intensified for barley grits and cornmeal but increased for oat bran, soybean hulls, and wheat bran. Total short-chain fatty acid production decreased as extrusion conditions intensified for barley grits, soybean hulls, and soybean flour. These data suggest that the effects of extrusion conditions on ingredient composition and digestion are influenced by the unique chemical characteristics of individual substrates.
The chemical composition and protein quality of 11 alternative protein sources (chicken products, blood products, enzyme-hydrolyzed fish protein concentrate, soybean meal, and spray-dried pork liver) were determined, and an experiment was conducted to determine palatability and digestibility of processed red blood cell-containing diets. Chicken protein sources differed in concentrations of CP, acid-hydrolyzed fat, and total AA (TAA) by 20, 31, and 24%, respectively, and GE by 1.7 kcal/g. Blood protein sources varied little in acid-hydrolyzed fat and GE concentrations, but concentrations of CP and TAA differed by 11 and 8%, respectively. Protein solubility of chicken and blood protein source categories averaged 57 and 69%, respectively. Protein solubility of enzyme-hydrolyzed fish protein concentrate, soybean meal, and spray-dried pork liver was 53, 67, and 26%, respectively. Based on calculations from immobilized digestive enzyme assay values, lysine digestibility averaged approximately 80.4 and 81.7% for blood and chicken protein sources, respectively. Lysine digestibility values for soybean meal and spray-dried pork liver were 89 and 77%, respectively. A chick protein efficiency ratio (PER) assay showed that chicken protein sources had high protein quality values, as the PER ranged from 2.7 to 5.3, whereas blood protein sources had poor protein quality (PER values less than 1.5). Enzyme-hydrolyzed fish protein concentrate, spray-dried pork liver, and soybean meal had high protein quality (PER values greater than 2.8). In the dog palatability and digestibility experiments, a corn and chicken-based diet supplemented with either 0 or 3% processed red blood cells was tested. The palatability test showed that dogs consumed more of the diet that contained 0% vs. 3% processed red blood cells. The intake ratio for the 3% processed red blood cells diet was 0.34. Nutrient digestibilities did not differ, except for CP, where the digestibility was greater (P = 0.01) for dogs consuming the 0% processed red blood cells diet. These data suggest that chemical composition and quality of alternative protein sources differ greatly among ingredients within the same category. Palatability data suggest that a processed red blood cells-containing diet is not highly palatable but, when this diet was offered as only one food, dogs demonstrated no aversion response but some decrease in protein digestion.
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