Flávio Prada

Effects of six carbohydrate sources on diet digestibility and postprandial glucose and insulin responses in cats

The effects of diets with different starch sources on the total tract apparent digestibility and glucose and insulin responses in cats were investigated. Six experimental diets consisting of 35% starch were extruded, each containing one of the following ingredients: cassava flour, brewers rice, corn, sorghum, peas, or lentils. The experiment was carried out on 36 cats with 6 replications per diet in a completely randomized block design. The brewers rice diet offered greater DM, OM, and GE digestibility than the sorghum, corn, lentil, and pea diets (P < 0.05). For starch digestibility, the brewers rice diet had greater values (98.6%) than the sorghum (93.9%), lentil (95.2%), and pea (96.3%) diets (P < 0.05); however, starch digestibility was >93% for all the diets, proving that despite the low carbohydrate content of carnivorous diets, cats can efficiently digest this nutrient when it is properly processed into kibble. Mean and maximum glucose concentration and area under the glucose curve were greater for the corn-based diet than the cassava flour, sorghum, lentil, and pea diets (P < 0.05). The corn-based diets led to greater values for the mean glucose incremental concentration (10.2 mg/dL), maximum glucose incremental concentration (24.8 mg/dL), and area under the incremental glucose curve (185.5 mg.dL(-1).h(-1)) than the lentil diet (2.9 mg/dL, 3.1 mg/dL, and -40.4 mg.dL(-1).h(-1), respectively; P < 0.05). When compared with baseline values, only the corn diet stimulated an increase in the glucose response, occurring at 4 and 10 h postmeal (P < 0.05). The corn-based diet resulted in greater values for maximum incremental insulin concentration and area under the incremental insulin curve than the lentil-based diet (P < 0.05). However, plasma insulin concentrations rose in relation to the basal values for cats fed corn, sorghum, pea, and brewers rice diets (P < 0.05). Variations in diet digestibility and postprandial response can be explained by differences in the chemical composition of the starch source, including fiber content and granule structure, and also differences in the chemical compositions of the diets. The data suggest that starch has less of an effect on the cat postprandial glucose and insulin responses than on those of dogs and humans. This can be explained by the metabolic peculiarities of felines, which may slow and prolong starch digestion and absorption, leading to the delayed, less pronounced effects on their blood responses.

Avaliação de dietas com diferentes fontes protéicas para cães adultos

The coefficient of apparent digestibility (CAD) of four dry extruded dog foods was compared, each one formulated with a different protein source: soybean meal (SM), corn gluten meal (GM), meat and bone meal (MBM) and poultry meal (PM). A completely randomized design was used, with four treatments (protein source) and six repetitions per treatment, in a total of 24 animals. Tukey test was used to compare treatments means. The diet based on GM showed the highest CAD of crude protein (88.13±0.40%), followed by SM (86.31±0.34%), MBM (85.88±0.16%), and PM (83.69±0.09%), with the lowest results. The CAD of dry matter was highest for PM (83.69±0.09%), intermediary for GM (82.41±0.23%) and MBM (82.76±0.11%), and lowest for SM (81.10±0.16%) The rations based on animal protein presented the highest CAD of nitrogen-free extract. The dogs fecal dry matter was higher for MBM, intermediary for PM and GM, and lower for SM. All the four protein sources analyzed have shown good CAD, and can be used in dog diets.

Uso de indicadores internos na avaliação da digestibilidade aparente de alimentos para gatos: comparação de métodos

The digestibility trials are important in the development and evaluation of animal feed. They are carned out through the total collection method (TC) or by the use of indicator methods (IM), where the indicators can be classified as external (added to the feed), or internal (already present in the feed). In the present work, the comparison of both methods was made, aiming the search for simpler and safer methods for the determination of the digestibility of commercial cat feed. We tested the TC and IM using, for the latter, the crudefibre (CF) and the acid-detergent fibre (ADF) as internal indicators. We used 4 young adult cats (2 males and 2 females) held in individual metabolism cages for 30 days (24 for adaptation and 6 for total collection of faeces) and fed ad libitum with a commercial dry extruded cat feed. The results for the TC, CF and ADF were, respectively, 74.0, 71.4 and 75.0% for dry matter, 77.0, 74.8 and 77.9% for organic matter, 79.2, 77.2 and 80.0% for crude protein, 81.7, 80.4 and 82.8% for ether extract and 78.8, 76.6 and 79.6% for nitrogen-free extract. The statistical analysis did not show significant differences between the methods (p > 0.2). It was recovered 96.1% of the ADF and 104.3% of the CF, and these figures could be considered statistically equivalents by the t test (p > 0.49). The internal markers method presents some practical advantages when compared to the total collection method. However, further studies are required in order to check the efficiency of the tested markers, using diets with different amounts and sources of CF and ADF.

Utilização de indicadores para estimar a digestibilidade aparente em gatos

The total collection (TC) method was compared to chromium oxide (Cr2O3), acid-insoluble ash (AIA) and lignin marker methods for determining the coefficients of apparent digestibility (CAD) of nutrients in domestic cats. The CAD of four diets were determined by TC and estimated for the three markers through tests. Twenty-four adult neutered cats were housed in individual metabolic cages, totaling six animals per diet. The experiment was carried out using a completely randomized design in subdivided blocks where diets were blocks, methods were sub-blocks and each cat an experimental unit. CAD for the lignin method was significantly lower than TC method (P<0.05) in one of the studied diets. CAD for the Cr2O3, AIA and TC methods were similar in all diets. Recuperation rates of Cr2O3, AIA and lignin markers were 97.1±2.5%, 97.3±2.9% and 83.9±9.1% respectively. AIA and Cr2O3 methods showed high potential for use as markers while the higher variability in results obtained with the use of lignin did not justify its usage as an indicator substance for felines.