The use of chromic oxide as a marker for measuring small intestinal digestibility in cannulated dogs

Reliability of acid-insoluble ash as internal marker for the measurement of digestibility in rabbits

<p>The present study aimed to evaluate acid-insoluble ash (AIA) as an internal marker for the measurement the coefficient of total tract apparent digestibility (CTTAD) in rabbits through two experiments (E1 and E2). In E1, 48 rabbits were used to calculate the CTTAD of the same basal diet according to the European reference method (ERM), the AIA and the titanium dioxide (TiO₂ with 1 g of TiO₂/kg diet) techniques (n=16 rabbits/method). The effect of feed sample quantity on dietary AIA content was investigated and total collection of faeces was carried out to calculate marker recovery. In E2, 48 rabbits were allotted to three groups fed diets with no sugar beet pulp (SBP0) or with 100 (SBP100) and 200 (SBP200) g sugar beet pulp/kg (n=16 rabbits/group). Each group was divided into two subgroups, ERM and AIA (n=8 rabbits/subgroup), in which CTTAD was measured using the European reference and AIA method, respectively. In AIA subgroups, only 10% of the total daily faecal output was sampled from 9:00 to 9:30 am. Feed analysis in E1 showed that increasing sample quantity from 5 to 9 g did not affect the dietary AIA content; however, the analytical error was 7 and 5 times lower (<em>P</em>&lt;0.05) for 9 g, when compared to 5 and 7 g samples. Feed analysis also showed 1.030±0.003 g TiO₂/kg diet. Faecal marker recovery was 99.80±0.03 and 96.89±0.16% for AIA and TiO₂, respectively. The CTTAD of dry matter (DM), did not differ between methods in E1, but a 5-fold higher variability (<em>P</em>&lt;0.05) was observed for the TiO₂ technique in comparison with the ERM and AIA methods. Also, no differences in the CTTAD of DM between the ERM and AIA methods were found in E2. In conclusion, AIA is a reliable internal marker in rabbits and offers the possibility of measuring the CTTAD of diets with precision, when complete faecal collection or feed intake measurement is not possible.</p>

A comparison of two methods to assess apparent total tract digestibility of nutrients in dogs

The apparent total tract digestibility (ATTD) of nutrients can be assessed by total collection of faeces (TC), which is the reference method, or by the indicator method (IM). Little information is available on proper faecal sampling methodologies for IM in canines to obtain results comparable to TC. The objective of this study was to determine the minimum number of sub-samples required for the IM to make it comparable with TC. A total of 11 adult male dogs were individually housed in metabolism cages. Dogs had access to a grass yard to facilitate defaecation. Faecal sub-samples (1/day) were taken from the daily faecal output to prepare the pooled samples for IM, obtaining cumulative sample combinations of 3 (IM3), 4 (IM4), 5 (IM5), 6 (IM6) and 7 d (IM7). Digestibility of dry matter, gross energy, crude protein and crude fibre was similar between TC and IM5, IM6 and IM7 (p > 0.05). The IM7 presented the greatest statistical similarity with TC. Nevertheless, IM was not a good predictor of crude fibre digestibility. In conclusion, IM can replace the TC method in dogs to evaluate ATTD of several nutritional fractions as long as the composite sample is collected during seven consecutive days. For estimation of fibre digestibility by IM, longer collection periods are probably required.

Digestibility index marker type, but not inclusion level affects apparent digestibility of energy and nitrogen and marker recovery in growing pigs regardless of added oat bran

This study was conducted to investigate whether the apparent ileal digestibility (AID) of GE or nitrogen (N) was influenced by inclusion level and type of digestibility index marker (DIM) and inclusion level of oat bran (OB) and whether the apparent total tract digestibility (ATTD) of GE or DIM recovery was influenced by the 3 aforementioned factors and duration of feces collection. Six diets were formulated as a 2 × 3 factorial arrangement with 2 levels of OB (0 or 100 g/kg) and 3 levels of DIM (2.5, 5.0, or 7.5 g/kg). Chromic oxide and titanium dioxide were used as DIM. Both chromic oxide and titanium dioxide were added to the same diet, and their inclusion levels were consistent in each experimental diet. In Exp. 1, 18 barrows fitted with T-cannulas at the distal ileum were used in a triplicate 6 × 2 incomplete Latin Square design with 6 dietary treatments and 2 periods. The ileal digesta were collected for 3 d after 5-d adaptation, and the AID of GE and N were determined by measuring Cr or Ti in diets and ileal digesta samples. In Exp. 2, a total of 72 barrows were used in a randomized complete block design, and the feces were collected for either 3 or 5 d after a 7-d adaptation according to the assignment. Experimental diets were same as Exp. 1. The ATTD of GE was determined by both total collection and index methods, and DIM recovery was determined by measuring Cr or Ti. In Exp. 1, there was no interaction among OB level, DIM level, and DIM type for AID of GE and N. The AID of GE and N determined by Ti were greater (P < 0.05) than Cr regardless of the OB level or DIM level. Neither the OB level nor the DIM level affected the AID of GE or N. In Exp. 2, no interaction among OB level, DIM level, duration of feces collection, and DIM type for ATTD of GE and DIM recovery was observed. The DIM level and duration of feces collection had no effect on ATTD of GE and DIM recovery. The total collection method resulted in greater (P < 0.05) ATTD of GE than Ti, which was greater (P < 0.05) than that determined by Cr. Similarly, the recovery of Ti was greater (P = 0.007) than Cr. Inclusion of 100 g/kg OB decreased (P = 0.003) ATTD of GE but did not affect the recovery of DIM. In conclusion, the AID of GE and N, the ATTD of GE, and the recovery of Cr or Ti were affected by DIM type, but not DIM level; the inclusion of OB had no effect on AID of GE and N, and DIM recovery; and the duration of feces collection had no effect on ATTD of GE and DIM recovery.

Prediction of in vivo short-chain fatty acid production in hindgut fermenting mammals: problems and pitfalls

Short-chain fatty acids (SCFA) are considered to have important physiological functions. However, to prove this, SCFA must be determined, which is rather difficult as a lot of factors interfere with their production. This review focuses on the factors that influence the prediction of short-chain fatty acid formation in the large intestine of monogastric mammals. To mimic the in vivo situation, when predicting the amount of short-chain fatty acids produced from a certain substrate based on in vitro models, one has to estimate the amount of this substrate entering the large intestine, the retention time in the different parts of the large intestine, and the substrate fermentability. Instead of in vitro models, direct and indirect techniques may be used to measure short-chain fatty acid production in vivo. Direct techniques include the measurement of input and output or measuring differences in SCFA between portal and venous blood whereas indirect techniques measure the end products of fermentation. In this case, other factors have to be taken into account, including technical limitations and ethical considerations. In this review it is concluded that the choice for a method will rely on the purpose of the study taking into account the (dis)advantages of every method.

Yttrium oxide (Y2O3) as an inert marker in digestibility studies with dogs, blue foxes and mink fed diets containing different protein sources

The study evaluated the use of yttrium oxide (Y(2)O(3)) as an inert marker in studies of apparent total tract digestibility in dogs, blue foxes and mink. Comparison was made with total faecal collection, and use of chromic oxide (Cr(2)O(3)) as marker respectively. Four experimental diets were added 0.1 g/kg yttrium oxide and 10 g/kg chromic oxide and fed to four animals of each species. Faecal recovery of yttrium oxide was 94.4% (SEM +/- 1.0), and of chromic oxide 105.8% (SEM +/- 1.5). The digestibilities of dry matter, crude protein, crude fat, starch and total carbohydrates obtained by total collection and yttrium oxide as marker showed close similarity, and in most cases not significant differences, independent of species and diets. In dogs, overall digestibilities of main nutrients with chromic oxide as marker were not significantly different from overall means obtained with yttrium oxide (p > 0.05). Overall digestibility of dry matter, crude protein and total carbohydrates in blue foxes and mink was significantly higher with chromic oxide than with yttrium oxide (p < 0.05). In dogs and blue foxes, digestibilities of individual amino acids determined by use of yttrium oxide were not different from values obtained using total collection of faeces, both within diets and for overall mean (p > 0.05). Overall amino acid digestibilities in dogs determined with chromic oxide as marker were similar to corresponding figures for yttrium oxide, whereas use of chromic oxide resulted in significantly higher digestibilites for a number of amino acids compared with yttrium oxide in foxes and mink (p < 0.05). The digestibilities of most main nutrients and amino acids revealed no interaction between diet and method (p > 0.05). The study showed that yttrium oxide can be used in low concentration in the feed, and allows high accuracy of analyses and thereby precise digestibility determination. It is concluded that yttrium oxide is an alternative inert marker to chromic oxide in the studied species.

Utilização de indicadores para estimar a digestibilidade aparente em gatos

Compararam-se os métodos de coleta total (CT) e dos indicadores óxido crômico (Cr2O3), cinzas insolúveis em ácido (CIA) e lignina na determinação dos coeficientes de digestibilidade aparente (CDA) dos nutrientes para gatos. Os CDA de quatro rações foram determinados pela CT e estimados pelos diferentes indicadores em teste. Foram utilizados 24 gatos adultos castrados, alojados em gaiolas metabólicas individuais, totalizando seis animais por ração. O experimento seguiu um delineamento inteiramente ao acaso, em parcelas subdivididas, sendo as rações as parcelas, os métodos as subparcelas e cada gato uma unidade experimental. Os CDA foram significativamente menores pelo método da lignina em uma das rações estudadas (P<0,05). Os métodos Cr2O3, CIA e CT resultaram em CDA iguais em todas as rações (P>0,05). As taxas de recuperação dos indicadores, médias±erro-padrão da média, foram, respectivamente, de 97,1±2,5%, 97,3±2,9% e 83,9±9,1% para o Cr2O3, CIA e lignina. A CIA e o Cr2O3 mostraram grande potencial para utilização como indicadores, enquanto a ampla variabilidade dos resultados obtidos com a utilização da lignina não justificou seu emprego como substância índice para felinos.