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

ABSTRACT

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.     

P and Ca digestibility is increased in broiler diets supplemented with the high-phytase HIGHPHY wheat

Around 70% of total seed phosphorus is represented by phytate which must be hydrolysed to be bioavailable in non-ruminant diets. The limited endogenous phytase activity in non-ruminant animals make it common practice to add an exogenous phytase source to most poultry and pig feeds. The mature grain phytase activity (MGPA) of cereal seeds provides a route for the seeds themselves to contribute to phytate digestion, but MGPA varies considerably between species and most varieties in current use make negligible contributions. Currently, all phytases used for feed supplementation and transgenic improvement of MGPA are derived from microbial enzymes belonging to the group of histidine acid phosphatases (HAP). Cereals contain HAP phytases, but the bulk of MGPA can be attributed to phytases belonging to a completely different group of phosphatases, the purple acid phosphatases (PAPhy). In recent years, increased MGPAs were achieved in cisgenic barley holding extra copies of barley PAPhy and in the wheat HIGHPHY mutant, where MGPA was increased to ~6200 FTU/kg. In the present study, the effect of replacing 33%, 66% and 100% of a standard wheat with HIGHPHY wheat was compared with a control diet with and without 500 FTU of supplemental phytase. Diets were compared by evaluating broiler performance, ileal Ca and P digestibility and tibia development, using nine replicate pens of four birds per diet over 3 weeks from hatch. There were no differences between treatments in any tibia or bird performance parameters, indicating the control diet did not contain sufficiently low levels of phosphorus to distinguish effect of phytase addition. However, in a comparison of the two wheats, the ileal Ca and P digestibility coefficients for the 100% HIGHPHY wheat diets are 22.9% and 35.6% higher, respectively, than for the control diet, indicating the wheat PAPhy is functional in the broiler digestive tract. Furthermore, 33% HIGHPHY replacement of conventional wheat, significantly improved Ca and P digestibility over the diet-supplemented exogenous phytase, probably due to the higher phytase activity in the HIGHPHY diet (1804 v. 1150 FTU). Full replacement by HIGHPHY gave 14.6% and 22.8% higher ileal digestibility coefficients for Ca and P, respectively, than for feed supplemented with exogenous HAP phytase at 500 FTU. This indicates that in planta wheat PAPhys has promising potential for improving P and mineral digestibility in animal feed.     

Determination of titanium dioxide added as an inert marker in chicken digestibility studies

A method was developed to determine the concentration of titanium dioxide in poultry digesta samples, obtained from the lower half of the small intestine of three-week-old male broiler chickens. Titanium dioxide was added at a rate of 5 g kg⁻¹ as a dietary marker.Only 0.1 g of freeze-dried digesta sample was required. The sample was ashed and dissolved in 7.4 M sulphuric acid. Hydrogen peroxide (30% vol.) was subsequently added, resulting in the typical orange colour the intensity of which was dependent upon the titanium concentration. Aliquots of the solutions obtained and of similarly prepared standard solutions were analysed using a UV spectrophotometer and measuring the absorbance at 410 nm.Validation of the method showed that:

• 1.1. Prepared samples could be kept for at least 48 h before measuring on the spectrophotometer.
• 2.2. Titanium dioxide recovery was not significantly affected by ashing or filtering of the sample during preparation.
• 3.3. Other components in the digesta sample did not affect absorbance.
• 4.4. Accurate and reproducible results were obtained when using the chicken digesta samples.

It was concluded that the method was suitable in the quantitative determination of titanium dioxide concentration in chicken digesta samples obtained during digestibility studies.     

Evaluation of titanium dioxide and chromic oxide as digestibility markers in ponies fed alfalfa hay in relation to marker dosing frequency

In equines, Cr₂O₃ is widely accepted as an indigestible marker, but there are health concerns regarding the carcinogenic properties of Cr₂O₃. Recently, TiO₂ has been suggested to be an alternative digestibility marker in equines. However, a comparison between Cr₂O₃ and TiO₂ has not been made in equines. Six Welsh pony geldings (initial BW: 254±3 kg; 7 years of age) fed chopped alfalfa hay were used to evaluate the use of TiO₂ (Ti) and Cr₂O₃ (Cr) as markers for calculating apparent digestibility and to investigate the effect of frequency of marker administration on the measurement of digestibility values. Diets contained 4.65 kg dry matter (DM) chopped alfalfa hay supplemented with minerals, vitamins, TiO₂ (3.3 g Ti/day) and Cr₂O₃ (3.2 g Cr/day). Ponies were dosed with either 3.3 g Ti and 3.2 g Cr once daily (DF1) or with 1.65 g Ti and 1.60 g Cr twice daily (DF2). After adaptation to the diets and procedures for 14 days, voluntary voided faeces were collected quantitatively over 7 days and analysed for moisture, ash, Ti and Cr. Apparent total tract DM digestibility (DMD) and organic matter digestibility (OMD) were calculated using the total faecal collection (TFC) and marker method (Ti and Cr). The overall mean cumulative faecal recovery of Cr and Ti (as % of intake) were 102.0% and 96.6%, respectively. Mean daily faecal recoveries of Cr as well as of Ti were not different (P=0.323; P=0.808, respectively) between treatments. Overall daily faecal recovery of Cr differed (P=0.019) from 100% when the marker was dosed once daily, whereas overall daily faecal recovery was similar to 100% for both administration frequencies when Ti was used as a marker. For both markers, the coefficient of variation of the mean faecal marker recovery between horses was lower when the markers were administrated twice per day. Across treatments, cumulative DMD and OMD estimated with Ti were similar (P=0.345; P=0.418, respectively) compared with those values determined by TFC method. When Cr was used, the calculated cumulative DMD tended (P=0.097) to be greater compared with those estimated with TFC, and cumulative OMD values were overestimated (P=0.013). Orally supplemented Ti recovery in the faeces of ponies fed chopped alfalfa hay with Ti administered once or twice daily was close to 100%, making it the preferred marker for digestibility trials in equines.     

Simultaneous inclusion of sorghum and cottonseed meal or millet in broiler diets: effects on performance and nutrient digestibility

Two experiments were conducted to investigate the use of sorghum, cottonseed meal and millet in broiler diets and their interaction when they are used simultaneously. In Experiment 1, a corn-soybean meal control diet was compared with eight experimental treatments based on low tannin sorghum (S30, S45 and S60), cottonseed meal (CM15, CM40) or both ingredients included in the same diet (S30/CM40, S45/CM25 and S60CM15). Results showed that BW gain was not affected by the inclusion of sorghum or cottonseed meal. However, feed intake tended to be affected by the cereal type with the highest values with sorghum-based diets. Feed conversion ratio increased (P<0.001) with sorghum-based diets compared with the control diet, whereas a combination of cottonseed meal and sorghum in the same diet did not affect the feed conversion ratio. Significant differences (P<0.001) were observed in apparent ileal digestibility (%) of protein and energy with the cottonseed meal and sorghum/cottonseed meal-based diets having lower protein and energy digestibility compared with corn-based diets. In Experiment 2, a control diet was compared with six diets in which corn was substituted at 60%, 80% or 100% by either sorghum or millet and other three diets with simultaneous inclusion of these two ingredients (S30/M30, S40/M40, S50/M50). Single or combined inclusion of sorghum and millet resulted in similar feed intake and growth performance as the control diet. Apparent ileal digestibility of protein and energy was higher with millet-based diets (P<0.001). Total tract digestibility of protein in sorghum and millet-based diets tended to decrease linearly with the increasing level of substitution. Sorghum-based diets resulted in lower total tract digestibility of fat compared with millet and sorghum/millet-based diets (P<0.001). Higher total tract digestibility of starch were obtained with the control diet and millet-based diets compared with the sorghum-based treatments. Results of the two experiments suggest that broiler growth performance was not affected by the dietary level of sorghum, millet or cottonseed meal. Nutrient digestion can, however, be affected by these feed ingredients.     

Influence of feed provisioning prior to digesta sampling on precaecal amino acid digestibility in broiler chickens

A regression approach was applied to determine the influence of feed provisioning prior to digesta sampling on precaecal (pc) amino acid (AA) digestibility in broiler chickens. Soybean meal was used as an example test ingredient. Five feed-provisioning protocols were investigated, four with restricted provision and one with ad libitum provision. When provision was restricted, feed was provided for 30 min after a withdrawal period of 12 h. Digesta were sampled 1, 2, 4 and 6 h after feeding commenced. A diet containing 300 g maize starch/kg was prepared. Half or all the maize starch was replaced with soybean meal in two other diets. Average pc digestibility of all determined AA in the soybean meal was 86% for the 4 and 6-h protocols and 66% and 60% for the 2 and 1-h protocols, respectively. Average pc AA digestibility of soybean meal was 76% for ad libitum feed provision. Feed provisioning also influenced the determined variance. Variance in digestibility ranked in magnitude 1 h > ad libitum > 2 h > 6 h > 4 h for all AA. Owing to the considerable influence of feed-provisioning protocols found in this study, comparisons of pc AA digestibility between studies applying different protocols prior to digesta sampling must be treated with caution. Digestibility experiments aimed at providing estimates for practical feed formulation should use feed-provisioning procedures similar to those used in practice.     

Transit time and digestibility of two experimental diets in the maned wolf (Chrysocyon brachyurus) and domestic dog (Canis lupus)

Recent research involving nutritional management of clinical disease secondary to cystinuria in captive maned wolves (Chrysocyon brachyurus) in the United States resulted in the production of a commercially manufactured maintenance diet and subsequently, a further modified experimental diet. These two diets differed only in their protein sources and sodium concentrations. The purpose of this study was to further investigate these diets by determining their digestibility and transit time in maned wolves, and also to compare these results to the digestibility and transit time of the diets in domestic dogs. The experiment consisted of two diets (maned wolf commercial maintenance diet and experimental diet) and two species (maned wolf and domestic dog [beagle]) arranged as a 2 × 2 factorial design. For the transit time study, titanium dioxide (TiO₂, 5 g/kg diet) was administered as a pulse dose and total collection of feces was carried out for 50 hr. There was no effect of diet or species on initial Ti recovery time (IRT), the amount of Ti recovered at IRT, or the time to reach 50% of Ti excretion in the feces. Maned wolves had lower total percent recovery (P<0.01) of Ti than dogs and shorter time to last recovery of Ti in the feces (P<0.05), however, marker excretion in the maned wolves may not have been complete. For the digestibility study, in which chromic oxide was used as a marker, fecal samples were collected on 2 consecutive days immediately after 12 days of being fed the diets and then analyzed for dry matter, energy, protein, and minerals. Crude protein, calcium, phosphorus, and zinc apparent digestibilities were unaffected by species or diet (P>0.05). Apparent digestibility of dry matter (P<0.05) and energy (P<0.01) were higher in the experimental diet and in the dogs. Both dogs and maned wolves fed the maintenance diet exhibited a greater apparent retention of copper, iron, and magnesium (P<0.01). Dogs had a higher apparent retention of magnesium and sodium than the maned wolves. Zoo Biol 0:1–13, 2006. © 2006 Wiley‐Liss, Inc.     

A comparison between the 2N and 4N HCl acid-insoluble ash methods for digestibility trials in horses

The digestibility of horse feeds and rations can be determined using different techniques such as calculations based on the chemical composition, in vivo or in vitro methods. The marker methods overcome difficulties like discomfort for the animals and longer experimental times encountered using the ingesta/egesta method. In field conditions, a natural indigestible marker like acid-insoluble ash (AIA), with no changes in the normal ration, could be a very useful tool for digestibility trials. A group of six standardbred horses was used in a set of seven apparent digestibility trials. The diets were based on a first-cut meadow hay added to three different cereals (barley for trials 1 and 2; oats for trials 3 and 5 and corn for trials 6 and 7), the hay : concentrate ratio being 60 : 40 or 70 : 30 on a dry matter basis. Feedstuffs and faeces were analysed to determine the AIA content, using 2N HCl or 4N HCl technique. No differences about AIA concentration were found between the two methods for means and accuracy in each diet. Digestion coefficients for each diet did not differ with AIA method, even if in some trials interfering factors consistently lowered the overall values. Consequently, the AIA 2N HCl can be considered the easier and cheaper method to state apparent digestibility in field conditions, and a good tool for digestibility trials in horses fed hay-based diets.     

Studies on the intestine section to be sampled in broiler studies on precaecal amino acid digestibility

Abstract

Measurements of precaecal amino acid digestibility with digesta sampled from slaughtered animals may be affected by the chosen length of the sampled section. The length needs standardization, therefore, when digestibility is understood to be a measure of feedstuff potential. It was our objective to study the change in the net disappearance of amino acids from the lower small intestine of broiler chicken. The section between Meckel's diverticulum and 2 cm anterior of the ileo-caeco-colonic junction was cut into three subsections of equal length: proximal, medial, and terminal. The contents of each subsection were pooled within the birds of each pen (12 in Experiment 1 and 10 in Experiment 2). TiO₂ was used as an indigestible marker. Prior to digesta sampling, broilers had been fed the experimental diets for seven days. In Experiment 1, two diets with either soybean meal or a mix of soybean meal and peas as the main protein sources were used. Each diet was allocated to eight pens and feeding commenced on day 14 of age. Net disappearance was significantly affected by diet only in regard to aspartic acid and methionine. No significant interaction between diet and subsection occurred. Net disappearance was significantly affected by subsection for all amino acids. It ranged from 74 – 92% for individual amino acids without significant differences in the medial and terminal subsections. Net disappearance was, however, between 3% and 9% lower in the proximal subsection. In Experiment 2, diets contained soybean meal as the main protein source and were given to 18 pens from day 22 of age. Again, the effect of subsection on net disappearance was significant for all amino acids. Net disappearance was significantly lower in the proximal than in the middle subsection, and differences ranged from 5 – 10%. Significant differences in the net disappearance were also found for most of the amino acids between the middle and the terminal subsection ranging from 2 – 4%. In conclusion, when precaecal amino acid digestibility should be used as a measure for a protein source's potential, digesta sampling should not consider the proximal third of the section between Meckel's diverticulum and the end of the ileum.     

Determination of titanium dioxide supplements in different matrices using two methods involving photometer and inductively coupled plasma optical emission spectrometer measurements

Titanium dioxide (TiO₂) is a viable marker in digestibility studies using different animal species. The photometrical analysis is based on an intense orange colour following the addition of hydrogen peroxide to an acid solution. The measurement using inductively coupled plasma optical emission spectrometry (ICP-OES) is a method for analysing more than one element from the same sample preparation. The present study was conducted to investigate whether an established ICP-OES element analysis following acid-based hydrolysis is appropriate for titanium analysis. Defined amounts of TiO₂ were added to samples obtained in studies with cows, pigs and turkeys and recoveries were determined. It was shown that supplemented TiO₂ can be determined in samples of feeds, faeces or excreta, and digesta using a method based on photometric or ICP-OES measurement. The differences between the true and measured titanium concentrations indicate that using the ICP-OES method leads to a higher accuracy of determination.     

Detoxification of cyanide using titanium dioxide and hydrocyclone sparger with chlorine dioxide

Abstract

The extraction of gold and silver from minerals and concentrates with cyanide is an important hydrometallurgy process that has been studied for more than 120 years. This technology, which consists of the dissolutions of the precious metals in cyanide solutions, followed by the recovery of the values by cementation, activated carbon or ion exchange resin. Most of the wastes in the industrial effluents’ milling are known to contain high contents of free cyanide as well as metallic cyanide complexes, which give them a high degree of toxicity. Appropriate methods for the treatment of cyanide solutions include cyanide destruction by oxidation using a photoelectrocatalytic detoxification technique with titanium dioxide microelectrodes. This is one of the most innovative ways for the treatment of wastewater containing cyanide. Another is the use of chlorine dioxide (ClO₂) with a gas-sparged hydrocyclone as the reactor. The results show that photodegradation of cyanide was 93% in 30 minutes using a 450 W halogen lamp, and in the case of ClO₂ the destruction of cyanides was 99% in 1 minute. In both cases, excellent performances can be achieved with the high capacity of these technologies.     

Photocatalytic inactivation rate of phage MS2 in titanium dioxide suspensions containing various ionic species

In the TiO₂ photoreaction system, the coexistence of NO₃ ^–, SO₄ ^2–, PO₄ ^3–, K⁺ or Ca²⁺ each at 10–100 mM decreased the rate constant for phage MS2 inactivation, but Cl^–, Br^– or Na⁺ did not. The inhibitory effects of the ions could be elucidated by the proportional relation found between the rate constants and quantities of the phage on TiO₂ irrespective of the kinds of existing ions.     

A comparison of two methods for estimating measurement repeatability in morphometric studies

1. Measurement repeatability is often reported in morphometric studies as an index of the contribution of measurement error to trait measurements. However, the common method of remeasuring a mounted specimen fails to capture some components of measurement error and could therefore yield inflated repeatability estimates. Remounting specimens between successive measurements is likely to provide more realistic estimates of repeatability, particularly for structures that are difficult to measure.
2. Using measurements of 22 somatic and genitalic traits of the neriid fly Telostylinus angusticollis, we compared repeatability estimates obtained via remeasurement of a specimen that is mounted once (single‐mounted method) versus remeasurement of a specimen that is remounted between measurements (remounted method). We also asked whether the difference in repeatability estimates obtained via the two methods depends on trait size, trait type (somatic vs. genitalic), sclerotization, or sex.
3. Repeatability estimates obtained via the remounted method were lower than estimates obtained via the single‐mounted method for each of the 22 traits, and the difference between estimates obtained via the two methods was generally greater for small structures (such as genitalic traits) than for large structures (such as legs and wings). However, the difference between estimates obtained via the two methods did not depend on trait type (genitalic or somatic), tissue type (soft or sclerotized) or sex.
4. Remounting specimens between successive measurements can provide more accurate estimates of measurement repeatability than remeasuring from a single mount, especially for small structures that are difficult to measure.

     

The use of titanium dioxide as an inert marker for digestion studies in raptors.

1. TiO2 is not a suitable marker for digestibility studies involving raptors. 2. Complete recovery of the 'inert' marker was not achieved. 3. Total collection of faeces is a more accurate method to determine food absorption. 4. Freezing sample solutions prior to colorimetric analysis can produce misleading results. 5. The percentage food absorbed from the intestine in Falconiformes is about 85% by dry weight.     

Photostabilized titanium dioxide and a fluorescent brightener as adjuvants for a nucleopolyhedrovirus

Titanium dioxide (TiO₂)reflects ultraviolet light, and so could beexpected to protect the occlusion bodies (OBs)of nucleopolyhedroviruses (NPVs) fromdegradation by sunlight. However, in thepresence of sunlight and water, TiO₂catalyzes the formation of hydrogen peroxide,which can degrade OBs. We tested microfineTiO₂ that had been photostabilized(particles were coated to prevent catalyticactivity), as a UV protectant for the OBs ofthe NPV of Helicoverpa zea (Boddie). Inthe absence of UV, activity of the OBs wasreduced by nonphotostabilized TiO₂ but wasunaffected by photostabilized TiO₂ or byzinc oxide (ZnO). None of these materialsinfluenced larval feeding rates. Undersimulated sunlight, photostabilizedTiO₂ protected the OBs to a greater degreethan did ZnO. Photostabilized TiO₂ wascompatible with a viral enhancer, thefluorescent brightener Blankophor HRS. Undersimulated sunlight, both materials increasedactivity of the OBs, relative to OBs withneither material, in a largely additive manner. In bioassays of foliage collected from fieldplots of lima bean plants sprayed with OBs withor without one or both of these materials,TiO₂ increased persistence of the OBs, butBlankophor HRS had no significant effect.     

两种分析方法在豹猫食物构成中的应用比较

豹猫(Prionailurus bengalensis)作为北京地区的顶级食肉动物,对于维持食物网结构和生态系统稳定性起到重要的生态作用。对于捕食动物食物构成研究,较为简便的方法是粪样内容物检视法,而粪样残余物DNA鉴定技术具有更为准确细致的优势,但也存在不足,探索不同方法的优势互补,将有助于提高技术应用成效。本研究利用DNA宏条形码技术与粪样内容物分析法,对采集自北京市4个自然保护区的71份豹猫粪样进行食物构成分析,比较两种分析方法的特点,了解豹猫的食物资源利用状况。结果显示,DNA宏条形码技术共鉴别出36种猎物,来自10目22科,4个保护区的豹猫食性具有显著差异,百花山、松山、云蒙山保护区的豹猫食物种类的出现比率均以小型哺乳类为主,其中对鼠类的捕食比例最高,对鸟类的捕食次之,而分布于云峰山保护区的豹猫对鸟类捕食比例最高,对鼠类的捕食次之。粪样内容物分析法鉴别出9类猎物,其中包括昆虫和植物两种DNA宏条形码技术未检出的食物,4个保护区的豹猫食物均以鼠类和鸟类为主,且最多检测出鼠类数量为3只、鸟类2只,次要食物则为植物和昆虫。两种方法均显示北社鼠(Niviventer confucia...     

A comparison of methods for determining compartmental analysis parameters

The traditional method for determining compartmental analysis parameters relies on a visual selection of data points to be used for regression of data from each cellular compartment. This method is appropriate when the compartments are kinetically discrete and are easily discernible. However, where treatment effects on compartment parameters are being evaluated, a more objective method for determining initial parameters is desirable.

Three methods were examined for determining initial isotopic contents and half-times of ⁸⁶Rb elution from cellular compartments using theoretical data with known parameters. Experimental data from roots of Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) and barley (Hordeum vulgare L.) intact seedlings were also used. The three methods were a visually assisted, linear regression on data of semilog plot of isotope elution versus time, a microcomputer-assisted, linear regression on semilog plot where maximization of the square of the correlation coefficient (r²) was the criterion to determine data points needed for each regression and a mainframe computer-assisted, direct nonlinear regression on elution data using a model of the sum of three exponential decay functions. The visual method resulted in the least accurate estimates of compartmental analysis parameters. The microcomputer-assisted and nonlinear regression methods calculated the parameters equally well.