Use Of Chromic Oxide Research Articles

Gut microbiota and gut morphology of gilthead sea bream (Sparus aurata) juveniles are not affected by chromic oxide as digestibility marker

The present work aimed to evaluate whether the use of chromic oxide (Cr2O3) as dietary inert marker in fish digestibility studies interferes with gut microbial community modulation and gut morphology. To assess the effects of Cr2O3 under potential diverse microbiota populations, dietary Cr2O3 was tested using challenging plant feedstuffs (PF)-based diets supplemented or not with prebiotics, as prebiotics are expected to modify gut microbiota populations. For that purpose, three diets were formulated to include circa 20:80 fish meal and PF as protein sources, without (CTR) or with prebiotic supplementation (10 g/kg XOS or GOS). These diets did not include Cr2O3 (−Cr2O3 diets). Three similar additional diets were formulated to include 5 g/kg Cr2O3 (+Cr2O3 diets). Cr2O3 effects on gut microbiota were assessed for the first time in the allochthonous (digesta) and autochthonous (mucosa) community by a culture-independent molecular approach, using denaturing gradient gel electrophoresis (DGGE). No differences in gut bacterial profiles (number of operational taxonomic units, microbiota richness, diversity and similarity indices) were observed between dietary treatments. No significant alterations in submucosa layer structure, enterocytes and eosinophilic granular cells structure, goblet cells and leucocytes quantity were detected in the distal intestine among diets. In conclusion, data indicate that dietary inclusion of 5 g/kg Cr2O3 does not interfere with gilthead sea bream (Sparus aurata) gut microbiota and gut morphology, suggesting that a dietary incorporation level of 5 g/kg Cr2O3 can safely be used as inert marker in digestibility studies.

223 Comparison of four digestibility markers to estimate fecal output of dogs

The use of chromic oxide is the standard marker for determining digestibility of dog diets. However, this method is not without issue regarding safety and repeatability. Therefore, it was our objective to determine the effect of using alternative markers to estimate fecal output and calculate diet digestibility. Four dietary treatments were produced from sorghum fractions (WSD, whole sorghum diet; FLD, sorghum flour diet; MFD; sorghum mill-feed diet) and rice, corn, wheat 1:1:1 (CON, control) as starch sources and fed to twelve Beagle dogs in a 4 × 4 replicated Latin square design. Fecal output was estimated using external markers Cr2O3 (0.25%) and TiO2 (0.40%) mixed with the diet prior to extrusion and acid insoluble ash (AIA) as an internal marker and by total fecal collection (TFC). Fecal output of OM, DM, CP, GE, crude fiber, and crude fat by the 4 different methods was analyzed and compared using Pearson partial correlation coefficients from the Error SSCP Matrix. Correlations (R2) were considered significant at P < 0.05. The TiO2 and Cr2O3 were highly (P < 0.05) correlated for estimates of fecal output of all nutrients: 0.93, 0.91, 0.91, 0.91, 0.99, and 0.93 for OM, DM, CP, crude fat, crude fiber and GE, respectively. The TiO2 also had significant correlations (P < 0.05) to TFC (0.59, 0.55, 0.61, 0.61, 0.82, and 0.60 for OM, DM, CP, crude fat, crude fiber, and GE, respectively) and AIA (0.84, 0.82, 0.82, 0.82, 0.84, and 0.86 for OM, DM, CP, crude fat, crude fiber, and GE, respectively). The Cr2O3 was also correlated (P < 0.05) to TFC (0.56, 0.50, 0.57, 0.57, 0.81, and 0.56 for OM, DM, CP, crude fat, crude fiber, and GE, respectively) and AIA (0.75, 0.71, 0.73, 0.73, 0.79, and 0.78 for OM, DM, CP, crude fat, crude fiber, and GE, respectively). The TFC and AIA methods had the poorest correlation among estimates of fecal outputs of OM, DM, CP, crude fat, crude fiber, and GE (0.29, 0.22, 0.33, 0.33, 0.54, and 0.33, respectively). Within these nutrients, only TFC and AIA for crude fiber fecal output correlated (P < 0.05). The study suggests that TiO2 may be a better marker to estimate fecal output in dogs than Cr2O3. TiO2 is considered GRAS and is a common colorant in pet foods. The use of the AIA technique needs to be further studied since it represents a potential option for evaluating diets that are difficult to incorporate external markers.

The use of chromic oxide as an index for determining the digestibility of feed constituents in buffalo calves

Six murrah buffalo calves divided into two groups were fed wheat straw and concentrates mixture along with green Lucerne. The average dry matter (DM) intake per 100 kg body weight (2.94 ± 0.36 kg) and g / unit metabolic size (g/w 0.75 ) (119.01 ± 7.54 g) were significantly higher (P < 0.05) in the animals of group II than the values obtained in the group I (2.25 ± 0.32 kg and 95.79 ± 10.03 g). The intake of digestible crude protein (DCP) g / unit metabolic size was lower (6.57 ± 0.57 g) in the males group than the females group (7.06 ± 0.71 g) whereas, the intake of total digestible nutrients (TDN) g / unit metabolic size was higher in the males group (77.79 ± 12.27) than the females group (68.02 ± 13.38). The differences in the intake and utilization of these nutrients between two groups of animals were statistically significant. The average digestibility co-efficients of DM, crude protein (CP), ether extract (EE), crude fibre (CF), nitrogen-free extract (NFE), total carbohydrates (TCHO), total ash, insoluble ash, neutral detergent fibre (NDF), acid detergent fibre (ADF) were 62.41 ± 1.13, 69.57 ± 0.89, 54.13 ± 1.81, 63.50 ± 0.86, 66.74 ± 2.79, 65.61 ± 3.29, 35.40 ± 2.08, 54.27 ± 1.38 and 74.73 ± 2.46 per cent in the animals of group I and 58.29 ± 1.44, 66.02 ± 0.36, 50.34 ± 0.49, 61.10 ± 0.79, 63.58 ± 1.80, 63.38 ± 2.41, 31.79 ± 1.39, 51.68 ± 0.71 and 68.64 ± 1.97 per cent in the animals of group II. Among the nutrients, the males digested more (P < 0.05) crude protein than the females.

Use chromium oxide and LIPE® as indicators in foreign estimate digestibility in ruminants

Knowing the amount of food ingested by an animal and how it absorbs nutrients is essential to make changes regarding food and animal's response, so the estimation of fecal output is one of the tools that assess the dry matter intake by ruminants, especially when considering the difficulties to determine it, in grazing animals. Therefore, this review seeks to compare the use of chromic oxide and LIPE ® as external markers to estimate digestibility of cattle.

Effects of dried distillers grains and equivalent undegradable intake protein or ether extract on performance and forage intake of heifers grazing smooth bromegrass pastures1

Crossbred heifers (n = 120; BW = 368 kg, SD = 39 kg) were used to determine effects of dried distillers grains (DDG) and relative contributions of undegradable intake protein (UIP) and fat (ether extract, EE) in DDG on ADG and forage intake (FI). Heifers rotationally grazed six 3.5-ha, smooth bromegrass paddocks (IVDMD = 65.7%, CP = 20.8%, UIP = 2.17%, DM basis). Heifers were blocked by previous ADG and allotted to treatments in a 3 x 3 + 1 factorial design. Factors were source and level of supplementation. Supplements were as follows: 1) DDG (UIP = 15.8%, EE = 9.67%), 2) corn gluten meal (CGM; UIP = 31.6%, EE = 0.83%), or 3) corn oil (OIL; UIP = 0.74%, EE = 19.3%). Amounts of DDG were 750, 1,500, or 2,250 g/d, whereas amounts of CGM and OIL were 375, 750, or 1,125 g/ d. Supplements containing CGM and OIL were fed in amounts that provided UIP and EE, respectively, equivalent to those of the DDG. Contrasts of interest were DDG vs. CGM and DDG vs. OIL. Control heifers were fed 250 g/d of a supplement containing corn bran and molasses (UIP = 0.92%, EE = 1.13%). Heifers were supplemented individually. Treatments were separated by regressing the response variables on grams of nutrient (DM, UIP, or EE) intake per kilogram of BW, because not all heifers consumed their allotment of supplement. Supplemental DDG resulted in a linear increase in ADG (P < 0.01), whereas CGM tended to increase ADG (P = 0.14) but at a rate that was 39% of that for DDG, representing a response to MP. Supplementation of OIL did not affect ADG (P = 0.25) and tended to result in ADG less than that of DDG (P = 0.09). Supplementation with DDG had no effect (P = 0.63) on FI when predicted by the use of chromic oxide but tended (P = 0.07) to decrease FI when it was predicted from ADG using NE equations. Despite the differences between methods in the significance of the effect of DDG, the rates of substitution agreed (-0.50 and -0.45 for chromic oxide and NE equations, respectively), suggesting that the chromic oxide method was less sensitive in assessing FI. Supplementation with CGM decreased FI (P < 0.01), but FI for CGM did not differ from that of DDG when the chromic oxide method was used (P = 0.19). Corn oil had no effect on FI (P = 0.42). Increased ADG and decreased FI observed from DDG supplementation is not independently explained by UIP or EE contained in DDG.

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.

The use of markers to determine energy metabolizability and nutrient digestibility in avian species

Apart from elimination of errors in obtaining exact measurements of feed intake and total faeces output in the traditional total collection method, the use of markers to determine nutrient digestibility of feeds in animal species would fit into animal welfare considerations. The external marker chromic oxide has been the prominent marker in the 1960s to evaluate metabolizable energy content of feeds for poultry. A preliminary feeding period of 5 days and collection of a sample representing day and night excreta over a 24 hour period have been suggested as protocol to get reliable results with the use of chromic oxide as marker. However, difficulty in obtaining repeatability between laboratories because of the analytical assay for chromic oxide, variability in results, incomplete and inconsistent recovery in excreta, and hazardous possibilities, resulted in replacement of the chromic oxide marker technique with the method of total excreta collection. Although titanium dioxide, which can be analysed by an accurate and simple colourimetrical assay, has been used in several studies in poultry, only one study has evaluated this marker for recovery (98%) in excreta. The internal marker, acid-insoluble ash, which also could present an external marker when the internal content is aided with the use of siliceous substances, is gaining popularity in recent times, although most studies presented higher digestibility values with this marker in avian species than those derived through the total excreta collection method. Lack of standardisation of analytical assays could partly explain the latter phenomenon. Although crude fibre has presented recovery rates of near 100% in excreta of laying hens and turkeys, fear of possible digestion of this substance by cecal microflora has prevented the further utilisation of this substance as marker. Lignin, determined by digestion in 72% sulphuric acid, presented recovery rates of 99 and 98% in chickens and ostriches, respectively, and similar (P>0.05) results than the total collection method in partridges. The elimination of the use of markers to determine energy metabolizability and nutrient digestibility with avian species have been based on a small number of studies conducted mainly before 1965, and extrapolation of results obtained with other animal species.

Effect of soybean meal particle size on amino acid and energy digestibility in grower-finisher swine.

A study was conducted using the ileal digestibility technique with grower-finisher pigs to evaluate the effects of particle size reduction of soybean meal (SBM) on amino acid and energy digestibility. Soybean meal was processed through a hammer mill to achieve average particle sizes of 900, 600, 300, and 150 microm. The treatments included the use of two soybean meal sources and soy protein concentrate. One source of SBM was ground to four different particle sizes (i.e., 949, 600, 389, 185); a second source was a common SBM source used in other trials (i.e., 800 microm). The soy protein concentrate had an average particle size of 385 microm. A low-protein (5% casein) diet was fed to determine endogenous amino acid losses. This experiment was conducted in a 7 x 7 Latin Square design in two replicates using 14 crossbred barrows ([Landrace x Yorkshire] x Duroc) that averaged 28 kg BW and 60 d of age. Animals were surgically fitted with a T-cannula at the distal ileum. Treatment diets were fed in meal form, initially at 0.09 kg BW(0.75) and at graded increases at each subsequent period. Pigs within replicate were fed a constant quantity of their treatment diet for a 5-d adjustment period followed by a 2-d collection of ileal digesta samples. Apparent and true digestibility of amino acids was calculated by use of chromic oxide (0.5%) as an indigestible marker. Apparent digestibility of isoleucine, methionine, phenylalanine, and valine increased linearly (P < 0.05) as particle size decreased. True digestibility of isoleucine, methionine, phenylalanine, and valine increased linearly (P < 0.05) as particle size decreased. When the essential amino acids were averaged, apparent digestibility increased (P < 0.10) from 83.5% to 84.9% as particle size decreased, whereas, nonessential amino acid digestibility increased only slightly (P > 0.15). Essential amino acid true digestibility increased numerically from 91.0% to 92.4% as particle size decreased. Energy digestibility was not affected by particle size (P > 0.15). These results suggest that a reduction in particle size of soybean meal resulted in a small increase in the digestibility of its amino acids with the essential amino acids being affected more than the nonessential amino acids. The largest improvement in digestibility, however, was obtained when the particle size was reduced to 600 microm.

An assessment of the use of chromic oxide as a marker in protein digestibility studies with Haliotis midae L.

A comparison between the total faecal collection method and chromic oxide marker technique in determining apparent protein digestibility coefficients in Haliotis midae, revealed that while the former was not a suitable methodology for use in this species, the latter produced replicable and reliable results. While three distinct types of faecal material were described, correlation analysis revealed a significant correlation between faecal chromic oxide and faecal protein ( r 2=0.89). It was established that at a dietary inclusion rate of 0.5%, the chromic oxide was inert, was not absorbed by the animal, did not interfere with the digestive process, and moved through the intestine at the similar rate to the protein. Of the three types of faecal material described, Type 1 faeces provided the most reliable estimates of apparent protein digestibility in this species.

A procedure for ileostomisation of adult roosters to determine apparent ileal digestibility of protein and amino acids of diets:: Comparison of six diets in roosters and growing pigs

A procedure for the ileostomisation of adult roosters has been described with the use of flexible silicon cannulas. Apparent ileal digestibility coefficients for dry matter (aDC DM), crude protein (aDC CP) and amino acids (aDC AA) in six diets, formulated with maize, wheat gluten, faba beans, lupins, soybean meal and casein as the main protein sources were determined in the ileostomised roosters fitted with silicon cannulas. In addition, aDC data determined using roosters (present study) were correlated with previously published aDC data of the same diets determined with pigs [van Leeuwen et al. (1996a). Apparent dry matter and crude protein digestibility of rations fed to pigs and determined with the use of chromic oxide (Cr203) and linsoluble ash as digestive markers. Br. J. Nutr. 76, 551-562; van Leeuwen et al. (1996b). Validation of a mathematical model to explain variation in apparent ileal amino acid digestibility of diets fed to pigs. J. Anim. Feed Sci. 5, 303-315]. The ileal aDC CP in roosters ranged from 0.81 to 0.92. Significant ( P<0.05) differences in aDC CP and aDC AA were observed between diets. Between aDC in roosters and pigs linear relations were found. The linear models explained 85% of the variation in ileal aDC CP between the six diets determined in roosters and pigs. For ileal aDC AA, the explained part of the variation between roosters and pigs, ranged from 62 to 96%, depending on the particular amino acids, with the exception of aDC of Arg. The standard errors (S.E.) of the models for the prediction of the aDC AA in roosters from aDC AA of the pigs was <0.04 units.

The digestibility of four ingredients in rainbow trout (Oncorhynchus mykiss Walbaum) diets

The marker technique has been used widely in trout digestibility studies due to practical difficulties in obtaining “true” faeces samples directly from fish. However this technique is also relatively difficult and there are few good systems for faeces collection. Reliable data on raw material digestibilities are therefore scarce. Traditionally, chromic oxide has been used as a marker. However this substance can give rise to skin allergies in humans and has been implicated as a carcinogen. Jagger et al., (1992) suggested that titanium dioxide could be used successfully as a digestibility marker in pig diets. The present study was designed to determine the digestibility of four feed ingredients for trout (prairie meal, maize distillers, soya 50 and extruded wheat) and to evaluate the use of chromic oxide or titanium dioxide as a digestibility marker in fish diets.Each test ingredient was included in a basal diet at 0, 100, 200, 300 and 400 g/kg. Titanium dioxide and chromic oxide were included in the basal diet at 1 and 3.7 g/kg respectively.

The digestibility of four ingredients in rainbow trout (Oncorhynchus mykiss Walbaum) diets

The marker technique has been used widely in trout digestibility studies due to practical difficulties in obtaining “true” faeces samples directly from fish. However this technique is also relatively difficult and there are few good systems for faeces collection. Reliable data on raw material digestibilities are therefore scarce. Traditionally, chromic oxide has been used as a marker. However this substance can give rise to skin allergies in humans and has been implicated as a carcinogen. Jagger et al., (1992) suggested that titanium dioxide could be used successfully as a digestibility marker in pig diets. The present study was designed to determine the digestibility of four feed ingredients for trout (prairie meal, maize distillers, soya 50 and extruded wheat) and to evaluate the use of chromic oxide or titanium dioxide as a digestibility marker in fish diets.Each test ingredient was included in a basal diet at 0, 100, 200, 300 and 400 g/kg. Titanium dioxide and chromic oxide were included in the basal diet at 1 and 3.7 g/kg respectively.

Apparent ileal dry matter and crude protein digestibility of rations fed to pigs and determined with the use of chromic oxide (Cr2O3) and acid-insoluble ash as digestive markers.

Two experiments were conducted to determine apparent ileal DM and crude-protein (CP) digestibilities in rations fed to pigs. An evaluation was made of Cr2O3 and HCl-insoluble ash as digestive markers. In addition, the effects of body weight (BW) on apparent ileal DM and CP (N x 6.25) digestibilities were studied. In Expt 1, thirteen barrows averaging 35 kg BW were fitted with post-valve T-caecum (PVTC) cannulas to determine the apparent ileal DM and CP digestibilities of a wheat gluten-bran ration (B2) and a soyabean-meal ration (E1). Immediately after morning feeding ileal digesta samples were collected on an hourly basis for a total of 12 h. Subsequently. N and marker contents were determined in the samples. The postprandial patterns of N and Cr passage were more similar than those of N and HCl-insoluble ash. Therefore Cr2O3 is more suitable as a marker than HCl-insoluble ash. The apparent ileal CP digestibility coefficient of ration B2 derived using Cr2O3 as a marker was significantly (P < 0.05) higher by 0.018 compared with the value obtained using HCl-insoluble ash. The corresponding values for ration E2 obtained using Cr2O3 and HCl-insoluble ash were both 0.825. In Expt 2, apparent ileal DM and CP digestibilities were determined in eighteen rations using twelve barrows also fitted with PVTC cannulas (BW from 40 to 100 kg). The protein sources for these rations were from different groups of feedstuffs. In four and three of the rations apparent ileal DM and CP digestibilities respectively were significantly different (P < 0.05) when assessed using the two markers. The digestibility coefficients were not systematically higher or lower for either marker. Absolute differences were < 0.049 on average. Significant effects of live weight on apparent ileal CP digestibilities were found.

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

Small intestinal digestibility can be measured by comparing feed with effluent collected from an ileal T-cannula. Nevertheless, a nondigestible, nonabsorbable marker, such as chromic oxide (Cr2O3), must be included in the diet because simple T-cannulae do not divert chyme completely. This study was conducted to evaluate the excretion pattern of Cr2O3 in cannulated dogs because the kinetics of Cr2O3 has not been previously investigated in this nonruminant species. Chromic oxide was added to four diets fed to eight cannulated mixed-breed dogs in a Latin-square design. The four diets contained reciprocal proportions of protein from texturized vegetable protein (0% to 57%) and from beef (100% to 43%), so protein and carbohydrate digestibility varied among diets. All feces were collected during wk 2 and all ileal effluent during wk 3 of each diet period. Ileal recovery of Cr2O3 was almost complete (94%) and was greater than fecal recovery (87%) (P < or = .03). Recovery was not different among diet groups. Ileal DM digestibility was approximately 2 percentage units lower on d 1 (P < or = .007) than on d 2 to 4. Nevertheless, ileal DM digestibility varied little on these subsequent days so single-day collections should be accurate. Chromic oxide concentration in chyme varied widely during each collection but increased at the start and declined towards the end of each collection. Spot sampling may therefore result in inaccurate estimates of nutrient digestibility. In conclusion, Cr2O3 may be used as a marker to measure digestibility in dogs with simple T-cannulae, but total collections should be attempted for greater accuracy.

Digestive Characteristics of the Sea‐Urchin Lytechinus variegatus (Lamarck) (Echinodermata: Echinoidea) Fed Prepared Feeds

Abstract Lytechinus variegatus were fed two prepared feeds identical in composition except one contained only soybean protein and the other contained equal concentrations of fish and soybean protein. Feeding rate, defecation rate, passage time through the gut, apparent dry matter digestibility of protein and carbohydrate, and the production of gut tissue did not differ significantly (P &gt; 0.05) with feed type. Individuals about 50 mm in diameter and 60% wet body‐weight consumed about 3‐g wet weight of feed per day. Feeding rate decreased during the experiment, but defecation rate did not. The throughput rate was two days with considerable mixing of feed in the gut. Fecal production ceased two days after cessation of feeding. Only trace amounts of feed remained in the gut three days after feed was not available. The apparent dry matter digestibility was 62% for soluble protein and 35% for soluble carbohydrate for both feeds. The apparent dry matter digestibility of ash was 19% for the feed with soybean meal alone, and 11% for soybean and fish meal. The apparent dry matter digestibility calculated by the use of chromic oxide is greater than that calculated by the use of ash.

Lipid nutrition in Arctic charr, Salvelinus alpinus (L.): a mini review

. Several investigations have used Cr2O3 (chromic oxide) as an indigestible marker in digestibility studies. However, in this review the effect of chromic oxide on dietary lipid during passage through the digestive tract, and the gastrointestinal microflora in long-term nutrition studies in Arctic charr, Salvelinus alpinus (L.), are discussed. Based on these results it is suggested that the use of chromic oxide may lead to erroneous results. Furthermore, this paper focuses on the effect of dietary linoleic add (18:2 n–6), acetate and salinity on lipid and individual fatty acid digestibilities in Arctic charr. No full studies have been carried out regarding the essential fatty acid requirement (EFA) of Arctic charr. Available data indicate that (n–3) polyunsaturated fatty acids (PUFAs) are the prime EFA, as in most other salmonids. Furthermore, quantitative EFAn requirements may be higher than the 1% dietary level described for other salmonids. Feeding (n–3) PUFAs at 1% lead to high contents of (n–9) PUFAs in the polar lipids, presently recognized as‘indicators’of EFA deficiency. Moreover, this review focuses on elongation and desaturation of short-chain EFA to their C20 C 22 counterparts, and the feedback inhibition of this ability.

Does chromic oxide (Cr2O3) affect faecal lipid and intestinal bacterial flora in Arctic charr. Salvelinus alpinus (L.)?

. Arctic charr. Salvelinus alpinus (L.), were fed a commercial diet with or without a supplement of 1% chromic oxide (Cr2O3) in fresh water at 8°C for 70 days. Supplementation of the diet with 1% chromic oxide did not affect the lipid composition of stomach contents, but did affect that of the faeces. Highest total lipid content in faeces was observed when fish were fed on the diet supplemented with chromic oxide. The proportion of triacylglycerols and free fatty acids increased in the neutral lipid fraction. The level of the dietary fatty acids 16:0, 16:1 and 18:1 increased, while 20:1 (n-9), 22:1 (n-11) and 18:2 (n-6) decreased significantly (P < 0·05) compared to the unsupplemented diet. Total viable counts (TVC) of aerobic microorganisms were somewhat higher in stomach contents when the charr were fed on the unsupplemented diet. In faeces from charr fed the unsupplemented diet, TVC were higher, by a factor of 10 compared to fish fed diet supplemented with chromic oxide. Bacterial composition in stomach content of both rearing groups were dominated by Pseudomonas sp. and Agrobacterium sp., but the number of Lactobacillus sp. and Streptococcus sp. enhanced in stomach content when the fish were fed on the chromic oxide enriched diet. The faecal bacterial flora were also different between the rearing groups. The predominant bacterial species present in the faeces of fish fed unsupplemented diet were identified as Pseudomonas sp. and Aeromonas sp. Other bacterial species isolated included Lactobacillus sp., Streptococcus sp., Agrobacterium sp., Flavobacterium sp. and Vibrio sp. In contrast, the bacteria flora in faeces of fish fed the chromic oxide diet was dominated by the Gram-positive bacteria Streptococcus and Lactobacillus. It is suggested that the use of chromic oxide as a marker in digestibility studies in Arctic charr may not be ideal.

The effect of cereal concentrate supplementation on the digestibility of herbage-based diets for lactating dairy cows

SummaryTwo experiments were conducted, one with seven and the other with eight lactating cows, to measure the effect of supplementation with a cereal concentrate on the digestibility of fresh herbage and to provide equations relating digestibility of herbage to faecal indicators. Cattle were housed with free access to fresh herbage from individual Calan–Broadbent gates for recording feed intake, and faecal output was estimated by the use of chromic oxide. In both experiments a cereal supplement depressed herbage organic matter digestibility by 8 g/kg for each kg of fresh concentrate provided within the range 1–6 kg. The depression was associated with reduced digestibility of cellulose. Herbage digestibility was significantly related to faecal nitrogen and faecal cellulose. Herbage intake was depressed by concentrate supplementation and the response in milk yield to supplementation was small.

Evaluation of the use of chromic oxide to estimate the feed intake of dairy cows

Abstract In each of 3 trials, the digestible organic matter (DOM) intake of 32 cows was determined by direct measurement and by a chromic oxide technique. Each trial involved either 2 or 3 21-day periods during lactation. Half of the cows had high Breeding Index (BI) and half had low BI. Cows were individually housed and offered pasture either ad libitum or 75070 ad libitum. Dosing with chromic oxide (10g Cr203 in a gelatin capsule) and sampling of faeces from the rectum occurred twice daily. Organic matter (OM) digestibility of the feed was obtained by in vitro determination, and both actual and estimated intakes are expressed as kg DOM per cow per week. Breeding Index had no significant effect on the relationship between estimated and actual intake. The chromic oxide technique consistently overestimated actual intake, but there were significant differences between weeks within and between periods in extent of overestimation. Mean overestimation was 14%. The variation in intake between cows of similar BI was greater for the chromic oxide technique. This resulted in the chromic oxide technique being less sensitive in detection of real differences in intake between the BI groups. Of the 33 comparisons in food intake of the 2 BI groups, significant differences were found on 31 and 18 occasions with the direct measurement and chromic oxide techniques respectively.

Emprego do óxido crômico, para a determinação da digestibilidade aparente da matéria seca, em perus (Meleagris Gallopavo)

The use of chromic oxide for determining dry matter digestibility was estudied; thus it was administered both in gelatin capsules or in the turkeys ration. 45 days old turkeys were randomly divided into four groups, two of which consumed 605 mg of chromicoxide, dayly, the others received it in the ration at 0,17% concentration on dry weigth basis. The faeces were collected during a 24 hour period. The methods, conventional and chromic oxide, were significantly different (P&lt;05), being the calculated alues obtained with the use of indicators systematically smaller than those derived from conventional test. Further, no differences were found between the two ways of chromic oxide administration.