Effect of exercise on apparent total tract digestibility of nutrients and faecal recovery of ADL and TiO2 in ponies

Exercise and physical training are known to affect gastrointestinal function and digestibility in horses and can lead to inaccurate estimates of nutrient and energy digestibility when markers are used. The effect of exercise on apparent nutrient digestibility and faecal recoveries of ADL and TiO₂ was studied in six Welsh pony geldings subjected to either a low- (LI) or high-intensity (HI) exercise regime according to a cross-over design. Ponies performing LI exercise were walked once per day for 45 min in a horse walker (5 km/h) for 47 consecutive days. Ponies submitted to HI exercise were gradually trained for the same 47 days according a standardized protocol. Throughout the experiment, the ponies received a fixed level of feed and the daily rations consisted of 4.7 kg DM of grass hay and 0.95 kg DM of concentrate. The diet was supplemented with minerals, vitamins and TiO₂ (3.0 g Ti/day). Total tract digestibility of DM, organic matter (OM), CP, crude fat, NDF, ADF, starch, sugar and energy was determined with the total faeces collection (TFC) method. In addition, DM and OM digestibility was estimated using internal ADL and the externally supplemented Ti as markers. Urine was collected on the final 2 days of each experimental period. Exercise did not affect apparent digestibility of CP, crude fat, starch and sugar. Digestibility of DM (DMD), OM (OMD), ADF and NDF tended to be lower and DE was decreased when ponies received the HI exercise regime. For all treatments combined, mean faecal recoveries of ADL and Ti were 87.8±1.7% and 99.3±1.7%, respectively. Ti was not detected in the urine, indicating that intestinal integrity was maintained with exercise. Dry matter digestibility estimated with the TFC, ADL and Ti for ponies subjected to LI exercise were 66.3%, 60.3% and 64.8%, respectively, while DMD for HI ponies were 64.2%, 60.3% and 65.2%, respectively. In conclusion, physical exercise has an influence on the GE digestibility of the feed in ponies provided with equivalent levels of feed intake. In addition, the two markers used for estimating apparent DMD and OMD indicate that externally supplemented Ti is a suitable marker to determine digestibility of nutrients in horses performing exercise unlike dietary ADL.     

Evaluation of methodological aspects of digestibility measurements in ponies fed different haylage to concentrate ratios

Methodological aspects of digestibility measurements were studied in four Welsh pony geldings consuming haylage-based diets with increasing proportions of a pelleted concentrate according to a 4×4 Latin square design experiment. Ponies were fed four experimental, iso-energetic (net energy (NE) basis) diets (i.e. 22 MJ NE/day) with increasing proportions of a pelleted concentrate (C) in relation to haylage (H). The absolute amounts of diet dry matter fed per day were 4.48 kg of H (100H), 3.36 and 0.73 kg of H and C (75H25C), 2.24 and 1.45 kg of H and C (50H50C) and 1.12 and 2.17 kg of H and C (25H75C). Diets were supplemented with minerals, vitamins and TiO₂ (3.7 g Ti/day). Voluntary voided faeces were quantitatively collected daily during 10 consecutive days and analysed for moisture, ash, ADL, acid-insoluble ash (AIA) and Ti. A minimum faeces collection period of 6 consecutive days, along with a 14-day period to adapt the animals to the diets and become accustomed to the collection procedure, is recommended to obtain accurate estimations on dry matter digestibility and organic matter digestibility (OMD) in equids fed haylage-based diets supplemented with concentrate. In addition, the recovery of AIA, ADL and Ti was determined and evaluated. Mean faecal recovery over 10 consecutive days across diets for AIA, ADL and Ti was 124.9% (SEM 2.9), 108.7% (SEM 2.0) and 97.5% (SEM 0.9), respectively. Cumulative faecal recovery of AIA significantly differed between treatments, indicating that AIA is inadequate to estimate the OMD in equines. In addition, evaluation of the CV of mean cumulative faecal recoveries obtained by AIA, ADL and Ti showed greater variations in faecal excretion of AIA (9.1) and ADL (7.4) than Ti (3.7). The accuracy of prediction of OMD was higher with the use of Ti than ADL. The use of Ti is preferred as a marker in digestibility trials in equines fed haylage-based diets supplemented with increasing amounts of pelleted concentrate.     

A comparison of total collection and marker technique for the measurement of apparent digestibility of diets for growing pigs

Use of markers for the measurement of digestibility is a less labour intensive method than total faecal collection. The objectives of the present study were: (1) to evaluate chromic oxide (Cr₂O₃), titanium dioxide (TiO₂) and acid-insoluble ash (AIA) markers for the calculation of digestibility and (2) to examine the reliability of grab sampling as a technique for measuring digestibility in group-housed animals. For marker comparison, eight entire males were housed in individual metabolism crates and offered a cereal-based diet. Pigs were randomly allotted to treatments for total collection period one, four to the diet with 1 g chromic oxide and 1 g titanium dioxide added per kilogram (Treatment A) and four to the same the diet without marker (Treatment B). During total collection period two, the treatments were reversed. AIA was measured for all animals in crates. For grab sampling study, grouped-housed animals (13–14 per pen) were fed the same cereal-based diet as for marker comparison above and AIA marker was used. Faecal samples were taken from a representative number of animals (minimum eight) in a pen while held in a weighing scales. All feed and faeces samples were analysed for marker content and digestibility. Feed analysis showed 0.93 g/kg of Cr₂O₃ and 1.02 g/kg of TiO₂ added to the diet. Faecal marker recovery was 96, 92.3 and 99.9% (S.E. 2.27) for Cr₂O₃, TiO₂ and AIA, respectively. Mean energy digestibility values were 0.858, 0.848, 0.844 and 0.855 (S.E. 0.003, P<0.01) for total collection, Cr₂O₃, TiO₂, AIA, respectively. Energy digestibility coefficients were 0.852 and 0.861 (S.E. 0.004, P>0.10) for total collection (as measured in marker comparison) and grab sampled animals, respectively. In conclusion, acid-insoluble is a reliable marker for the measurement of digestibility and grab sampling offers a rapid and reliable alternative to the labour intensive metabolism crate method.     

Measurements of digestibilities of cholesterol and fatty acids using 5α-cholestane as an inert marker in the tilapia, Oreochromis niloticus, and the freshwater prawn, Macrobrachium rosenbergii

An attempt was made to measure the apparent digestibility (AD) of cholesterol and fatty acids using 5aL-cholestane as a marker (cholestane-method) using tilapia. Oreochromis niloticus, and the freshwater prawn, Macrobrachium rosenbergii, as test animals. The results were compared with those obtained by the Cr₂O₃-method. Casein-based test diets containing 0.3% levels of cholestane and chromic oxide as markers were prepared for determination of AD of dietary cholesterol and fatty acids. After 2 weeks of acclimation, the test animals, tilapia (average 3.0 g wet weight) and freshwater prawn (average 0.5 g wet weight) were fed the test diets for 1 week, and faecal samples were collected over 6 subsequent days. Lipids in the diets and faeces were extracted with chloroform-methanol and saponified with 10% KOH in methanol. Gas-liquid chromatography (GLC) on 1.5% OV-17 of the unsaponifiable matters afforded the quantities of 5aL-cholestane and cholesterol, whereas that on 5% Shinchrom E-71 of the saponifiable matters provided the quantities of fatty acids. Chromic oxide was determined by a wet-digestion method. In tilapia, the AD of cholesterol determined by cholestane- and Cr₂O₃-methods were 78.1% and 73.5%, respectively. The AD of individual fatty acids differed with the types of fatty acids, but those of fatty acids determined by the two methods in this study were similar, except for a slightly higher value of several fatty acids such as 16:1 in the cholestane-method than in the Cr₂O₃-method. This indicates that 5α-cholestane as well as Cr₂O₃ can be conventionally used as a marker for determining AD of fatty acids and cholesterol. The cholestane-method is advantageous as it permits parallel analysis of cholesterol (or fatty acids) and 5α-cholestane by GLC using small amounts of faecal sample. The cholestane-method was also useful for analysing digestibilities of cholesterol and total lipids in freshwater prawn. However, slight differences between the cholestane- and Cr₂O₃-methods were observed in the AD of several fatty acids such as 14:0 and 16:1.     

Digestibility and energy value of cereal-based diets in relation to digesta viscosity and retention time in turkeys and chickens at different ages estimated with different markers

Digesta viscosity, ileal transit time of digesta, apparent ileal protein digestibility and apparent metabolisable energy (AME_N) of diets based on wheat and dehulled barley (WB), oats (O) or a mixture of these (WBO) fed as such or with enzyme supplementation in three- and six-week old turkeys and broilers were investigated. In addition, differences between ileal digestibility and AME_N calculated by using titanium dioxide (TiO₂), chromic oxide (Cr₂O₃) or acid insoluble ash (AIA) as indigestible markers were compared. Digesta viscosities were generally moderate reaching from 2.5 mPa · s to 7.3 mPa · s. The highest viscosities were observed in WBO diets. Viscosities were reduced with age in broilers, and were generally higher in turkeys than in broilers, especially at six weeks of age. Digesta retention time in ileum was elongated with age of the birds, pronouncedly in broilers. Oat inclusion to the diets decreased retention time especially in broilers at six weeks of age. Apparent ileal digestibility of protein ranged from 0.64–0.83, was lower at six weeks of age than at three weeks of age and generally lowest in O diets, especially in turkeys. AME_N of the diets ranged from 11.2–13.4 MJ/kg being higher at six weeks of age than at three weeks of age. AME_N of Diets O was the lowest but AME_N of WBO diets was higher than that of WB diets indicating a synergistic interaction of cereals, this trend being more pronounced in broilers. Enzyme supplementation decreased viscosity and improved AME_N in most diets, but did not affect ileal protein digestibility. Differences between ileal digestibility estimates obtained with TiO₂ or Cr₂O₃ were small and mainly not significantly different from 0. AME_N estimates were generally higher when calculated with Cr₂O₃ than with TiO₂. AIA gave remarkably lower AME_N values than TiO₂ (the significant differences ranging from 0.24–0.94 MJ/kg). In addition, effects of markers on AME_N estimates interacted with age of the birds and dietary treatments.     

Samarium doped titanium dioxide nanoparticles as theranostic agents in radiation therapy

PurposeTitanium dioxide nanoparticles (TiO₂ NPs) have been investigated for their role as radiosensitisers for radiation therapy. The study aims to increase the efficiency of these NPs by synthesising them with samarium.MethodsSamarium-doped TiO₂ NPs (Ti(Sm)O₂ NPs) were synthesised using a solvothermal method. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS) were performed for characterising of the Ti(Sm)O₂ NPs. The intracellular uptake and cytotoxicity were assessed in vitro using A549 and DU145 cancer cell lines. Furthermore, the effect of dose enhancement and generation of reactive oxygen species (ROS) in response to 6 MV X-rays was evaluated. Additionally, the image contrast properties were investigated using computed tomography (CT) images.ResultsThe synthesised Ti(Sm)O₂ NPs were about 13 nm in diameter as determined by TEM. The XRD pattern of Ti(Sm)O₂ NPs was consistent with that of anatase-type TiO₂. EDS confirmed the presence of samarium in the nanoparticles. At 200 μg/ml concentration, no differences in cellular uptake and cytotoxicity were observed between TiO₂ NPs and Ti(Sm)O₂ NPs in both A549 and DU145 cells. However, the combination of Ti(Sm)O₂ NPs and X-rays elicited higher cytotoxic effect and ROS generation in the cells than that with TiO₂ NPs and X-rays. The CT numbers of Ti(Sm)O₂ NPs were systematically higher than that of TiO₂ NPs.ConclusionsThe Ti(Sm)O₂ NPs increased the dose enhancement of MV X-ray beams than that elicited by TiO₂ NPs. Samarium improved the efficiency of TiO₂ NPs as potential radiosensitising agent.     

A dual marker technique to estimate individual feed intake in young pigs

Accurate estimation of individual feed intake (FI) of pigs could help better understand the variation in performance between individual animals. We studied dual marker methods to estimate individual FI in pigs. This method is based on the measurement of the ratio between two indigestible markers in faeces. Twelve 6.5-week-old individually housed male pigs were assigned to one of three oral dosing treatments supplying 180 mg of ytterbium chloride (YbCl₃)/day and 111 mg of dotriacontane (C32)/day as reference markers, either once (R1), three times (R3) or five times (R5) daily. Pigs were offered a diet containing 0.46 g/kg of chromium chloride (CrCl₃) and 0.15 g/kg of hexatriacontane (C36) as in-feed markers. The experiment lasted for 10 days: days ?5 to 0: adaptation; days 1–3: dosing of reference marker; days 2–4: total faecal collection. Spot faecal samples were taken on day 3 at 1200 h, 1700 h and on day 4 at 0700 h. Pigs were fed restrictedly three times daily, at 133.6 g/kg BW^0.60. Individual measured FI was recorded daily and was compared to predicted FI using the ratio of the dual marker pairs (Yb:Cr and C32:C36), both in total faecal collection and spot samples. Due to unequal variance, R1 pigs were omitted from the statistical treatment comparison. When using total faecal collection samples, the absolute prediction error (APE) (predicted FI minus measured FI) in R3 and R5 pigs was numerically lower than in R1 pigs, regardless of the marker pair used. The APE measured by C32:C36 was numerically lower than measured by Yb:Cr at all frequencies, and significantly (P = 0.039) in R3 pigs (C32:C36: 0.15 ± 0.02 kg/day; Yb:Cr: 0.29 ± 0.04 kg/day). This was related to a larger difference in faecal recovery between Yb and Cr compared with C32 and C36. Daily total faecal collection revealed that for R3 pigs, starting faecal collections 2 days after the onset of provision of the reference marker improved the APE when compared with starting after 1 day. When using C32:C36 to predict feed intake, pooled, but not single spot samples gave similar APEs compared with total faecal collections. Therefore, we recommend dosing the reference marker three times per day for 2 days on days 1 and 2, combined with pooled spot faecal sampling collected on days 3 and 4. In this way, absolute prediction errors of 10%-15% of simultaneously measured intakes of multiple nutrient resources in a complex housing system are feasible using the dual marker technique.     

Pycnogenol prevents potassium dichromate (K2Cr2O7)-induced oxidative damage and nephrotoxicity in rats

Environmental and occupational exposure to chromium compounds, especially hexavalent chromium [Cr(VI)], is widely recognized as a potential nephrotoxic in humans and animals. Its toxicity is associated with overproduction of free radicals, which induces oxidative damage. Recent evidence indicates that Pycnogenol^® (PYC), French maritime pine bark extract, exhibits antioxidant potential and protects against various oxidative stressors. The aim of the present study was to examine the modulating impacts of PYC on potassium dichromate (K₂Cr₂O₇)-induced oxidative damage and nephrotoxicity in rats. Male Wistar rats were divided into four groups. The first group was control, the second group was control plus pre-treated with PYC (10 mg/kg, body weight; in saline; intraperitoneally; once daily for 3 weeks) as drug control and the third group was saline pre-treated plus treated with a single injection of K₂Cr₂O₇ (15 mg/kg, body weight; in saline; intraperitoneally) as toxicant group. The fourth group was PYC pre-treated plus K₂Cr₂O₇ injected. Forty-eight hours after K₂Cr₂O₇-treatment, blood was drawn for estimation of renal injury markers in serum. Rats were then sacrificed, and their kidneys were dissected for biochemical and histopathological assays. K₂Cr₂O₇-treated rats showed significant increases in markers of renal injury in serum, including blood urea nitrogen (BUN), serum creatinine (Scr), and alkaline phosphatase (ALP), which were significantly (P < 0.05) decreased by PYC pre-treatment. Moreover, prophylactic pre-treatment of rats with PYC significantly (P < 0.05) ameliorated increased thiobarbituric reactive substances (TBARS), malonaldehyde (MDA) and protein carbonyl (PC), and decreased levels of glutathione (GSH) and catalase activity in the kidney homogenate of K₂Cr₂O₇-treated rats. These results were also supported and confirmed with histopathological findings. The study suggests that PYC is effective in preventing K₂Cr₂O₇-induced oxidative mediated nephrotoxicity, but more studies are needed to confirm the effects of PYC as a nephroprotective agent.     

Seasonal changes in composition and intake of chaparral by Spanish goats

Seasonal changes in utilization of one-year regrowth of chaparral vegetation by Spanish goats were investigated. The dominant shrub species were: oak (Quercus dumosa and Q. wislizenii), chamise (Adenostoma fasciculatum), manzanita (Arctostaphylos glandulosa) and ceanothus (Ceanothus cuneatus, and C. foliosus). Oesophageal and faecal samples were obtained during the spring, summer and autumn seasons of 1979. Mean daily temperatures for the three seasons were 19, 18 and 12° C, respectively. Winter sampling was restricted by cold weather at the 985-m elevation site. Cover was measured from ten permanent transects. Preference of Spanish goats was highly directed towards oak (> 50%) and chamise (> 30%) in all seasons.Correlation of selectivity (percentage botanical composition in the diet) and availability data indicated that goats may be generalist in their feeding strategies, but display some sort of specialized behaviour in selecting between the most dominant species. The observation that selection of herbaceous vegetation was restricted by availability conforms with the recent classification of goats as adaptive mixed feeders rather than browsers.Daily feed intake (g DM/kg BW^0.75) was calculated by dividing faecal residue by (100—digestibility in vitro). Intake values were equivalent to maintenance requirements during spring (60 g) and summer (57 g). However, autumn chaparral provided sub-maintenance intake levels (36 g). Condensed tannins (ADF—NAD), estimated as the difference between acid detergent fibre (ADF) and sequential acid detergent residue of neutral detergent residue (NAD), were variable in the clipped shrub samples but low in all dietary samples (2.1 ± 1.8%). The low levels of tannins did not appear to be affecting utilization of this browse.Predictive equations for intake (DMI) and digestibility in vitro (IVOMD) were derived from step-wise regression analysis using the following independent variables: cell wall content (CWC), NAD, cellulose (NADC), NAD sulphuric acid insoluble lignin (NADL_s), hemicellulose (NADHC), lignin: ADF—NAD tannins, ash and nitrogen (N) The equation for intake was: DMI (g DM/kg BW^0.75) = ?25.67 + 1.80 OMD (n = 56, Syx = 17.72, r = 0.59, P < 0.005), while digestibility (%) was predicted as OMD = 56.98 ? 0.46 CWC ? 0.45 NADL_s + 0.65 N + 0.09 DMI (n = 56, Syx = 2.77, r = 0.88, P < 0.005).It is concluded that recently-burnt chaparral vegetation would provide a maintenance browse for Spanish goats during the spring and summer seasons only.     

Polyethylene glycol marker measured with NIRS gives a reliable estimate of the rangeland intake of grazing sheep

Polyethylene glycol (PEG) measured with NIRS is known to be a valuable faecal marker when used in indoor experiments. In order to verify whether it can be used at pasture, an experiment was conducted with two trials. In trial 1, six Romane breed adult dry ewes placed in metabolism cages were fed daily with natural, freshly cut rangeland from a fertilised or unfertilised paddock for 6 weeks. Three ewes did not receive PEG and the three others were dosed with 10 g of PEG in solution form once daily until the end of the experiment to measure in vivo dry matter digestibility and PEG recovery rate for each forage quality. At the same time (trial 2), 15 ewe lambs and 14 lactating adult ewes suckling one or two lambs were allowed to graze together on the same herbage as that cut for indoor ewes. All animals were initially equipped with faecal bags emptied twice daily for collecting total faeces, and eight ewe lambs and seven adults were dosed once daily with 10 g of PEG. Faecal grab samples were collected for 4 to 5 days for each forage quality grazed. Indoor trial 1 showed that PEG had no effect on dry matter intake (DMI) or on digestibility. PEG recovery rates measured on fertilised (77.7%) and unfertilised (82.1%) forage were not different (P>0.05). PEG recovery rates measured at pasture did not differ (P>0.05) between pasture quality and animal type with an average value of 68.9%. Faecal output measured with bags or estimated with PEG and calculated DMI were not different (P>0.05) when PEG recovery rate measured at pasture was used. Conversely, using indoor PEG recovery values, significantly (P<0.05) or tended to overestimate faecal output. In conclusion, PEG could be used as a faecal marker administered at a minimal dose of 1% of DMI with a recovery rate measured under pasture conditions for pasture intake measurements on a group of animals at the same physiological stage but not for individual measurements.     

Ecophysiological responses of water hyacinth exposed to Cr3+ and Cr6+

Due to its wide industrial use, chromium (Cr) is considered a serious environmental pollutant of aquatic bodies. In order to investigate the ecophysiological responses of water hyacinth [Eichhornia crassipes (Mart.) Solms] to Cr treatment, plants were exposed to 1 and 10 mM Cr₂O₃ (Cr³⁺) and K₂Cr₂O₇ (Cr⁶⁺) concentrations for two or 4 days in a hydroponic system. Plants exposed to the higher concentration of Cr⁶⁺ for 4 days did not survive, whereas a 2 days treatment with 1 mM Cr³⁺ apparently stimulated growth. Analysis of Cr uptake indicated that most of the Cr accumulated in the roots, but some was also translocated and accumulated in the leaves. However, in plants exposed to Cr⁶⁺ (1 mM), a higher translocation of Cr from roots to shoots was observed. It is possible that the conversion from Cr⁶⁺ to Cr³⁺, which immobilizes Cr in roots, was not total due to the presence of Cr⁶⁺, causing deleterious effects on gas exchange, chlorophyll a fluorescence and photosynthetic pigment contents. Chlorophyll a was more sensitive to Cr than chlorophyll b. Cr³⁺ was shown to be less toxic than Cr⁶⁺ and, in some cases even increased photosynthesis and chlorophyll content. This result indicated that the F_v/F₀ ratio was more effective than the F_v/F_m ratio in monitoring the development of stress by Cr⁶⁺. There was a linear relationship between qP and F_v/F_m. No statistical differences were observed in NPQ and chlorophyll a/b ratio, but there was a tendency to decrease these values with Cr exposure. This suggests that there were alterations in thylakoid stacking, which might explain the data obtained for gas exchanges and other chlorophyll a fluorescence parameters.     

Homoleptic binuclear chromium carbonyls: why haven’t they been synthesized as stable molecules?

Density functional theory has been used to explore possible homoleptic binuclear Cr carbonyls Cr₂(CO)_n (n = 11, 10, 9, and 8) using the pure DFT method BP86 and the hybrid Hartree-Fock DFT method B3LYP. The binuclear Cr₂(CO)₁₁ is computed to be thermodynamically unstable with respect to dissociation into mononuclear fragments in contrast to the experimentally known Cr₂(CO)₁₀(μ-H)⁻. This may account for the failure to synthesize Cr₂(CO)₁₁ as a stable compound. Optimized structures for the formally unsaturated Cr₂(CO)₁₀ are a singlet with two four-electron donor bridging CO groups and no formal metal-metal bonding and a triplet with no bridging CO groups and a CrCr double bond similar to the OO bond in O₂. The more highly unsaturated homoleptic binuclear chromium carbonyls Cr₂(CO)₉ and Cr₂(CO)₈ are computed to be stable with respect to dissociation into mononuclear fragments in contrast to Cr₂(CO)₁₁ and Cr₂(CO)₁₀. The optimized structure for Cr₂(CO)₉ is a singlet Cr₂(CO)₆(μ-CO)₃ with a short metal-metal distance (∼2.3 Å) consistent with the Cr≡Cr triple bond required for an 18-electron configuration for each Cr atom. The global minimum for Cr₂(CO)₈ is a closely related Cr₂(CO)₅(μ-CO)₃ structure derived from the Cr₂(CO)₆(μ-CO)₃ global minimum by loss of one of the terminal CO groups with little change in the Cr≡Cr distance. Higher energy minima for Cr₂(CO)₈ include two different Cr₂(CO)₆(μ-CO)₂ structures, one formulated with two four-electron donor μ-CO groups bridging two Cr(CO)₃ groups and the other with similar μ-CO groups bridging a Cr(CO)₄ and a Cr(CO)₂group.     

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.     

Acid‐insoluble ash as a measure of dry matter digestibility in captive African elephants (Loxodonta africana)

There are limited data on the diet dry matter digestibility (DMD) of captive African elephants. Although the total fecal collection method is the standard for determining DMD, it is labor‐intensive, time‐consuming, and expensive. The acid‐insoluble ash (AIA) marker technique has been used successfully to determine DMD in ruminants and monogastrics. The objective of this study was to assess how accurately the AIA marker technique could estimate the DMD of captive African elephants (Loxodonta africana). Three mature male African elephants at Disney's Animal Kingdom in Florida were used in this study. The animals were offered a Bermuda grass hay‐based ration, and the total dry matter intake (DMI) and total fecal output were measured daily over a 7‐day period to determine the total collection DMD. The feed ingredients and fecal samples were also analyzed for AIA. Although there were differences (P<0.05) in total DMI and total fecal outputs, the DMD values did not (P>0.05) differ (35.1±0.72 vs. 37.1±0.72 for total collection and AIA, respectively). There was a linear (y=0.9461x; R²=0.74) relationship between the total collection and AIA marker technique DMD values. These results suggest that AIA can be used to accurately estimate the DMD of captive African elephants. Zoo Biol 0:1–5, 2005. © 2005 Wiley‐Liss, Inc.     

Comparative studies of chromosomal aberration and mutagenicity of trivalent and hexavalent chromium

The comparative cytogenetic and mutagenic effects between trivalent and hexavalent chromium were investigated. Five chromium compounds, K₂Cr₂O₇ and K₂CrO₄ containing Cr⁶⁺, and Cr(CH₃COO)₃, Cr(NO₃)₃ and CrCl₃ containing Cr³⁺, were examined for their ability to induce chromosomal damage in cultures of human leukocytes, for their reactivity with DNA by a rec-assay system and for mutagenicity in the E. coli Hs30R test system.Chromosome-breaking activity was significantly higher for the compounds with hexavalent than trivalent chromium, the efficiency being in the decreasing order K₂Cr₂O₇ > K₂CrO₄ >> Cr(CHCOO)₃ > Cr(NO₃)₃, CrCl₃. In the rec-assay and mutation assay, hexavalent (K₂Cr₂O₇ and K₂CrO₄) and trivalent Cr(CH₃COO)₃) compounds gave positive results, their mutagenic potential being higher in the same order of clastogenic magnitude.     

Evaluation of green forage intake and digestibility in ruminants using near infrared reflectance spectroscopy (NIRS): Developing a global calibration

The objective of this study was to evaluate the potential of near infrared reflectance spectroscopy (NIRS), applied to forage and/or faeces, to estimate the in vivo organic matter digestibility (OMD) and the organic matter voluntary intake (OMVI, g/kg metabolic weight [BW^0.75]) for a wide range of temperate forages. Two different databases, in terms of forage species and development stages were studied. The first one included two grass species and two forage mixtures for which OMD and OMVI were continuously measured during the grass-growing seasons (spring and summer). The second one contained a large set of grass and legume species and forage mixtures (142 trials) for which OMD and OMVI were measured.Forage and faeces samples were submitted to NIRS analysis and predictive calibrations were developed from forage spectra, faeces spectra, forage and faeces subtracted spectra, and faeces and forage concatenated spectra. Working on faecal spectra (alone or concatenated) enabled us to develop the best calibration equations for both OMD and OMVI estimation. The coefficient of determination (R²) was greater than 0.8. The standard error of cross validation (SECV) for OMD and OMVI was 0.021 and 4.51 g/kg BW^0.75, respectively, and the accuracy was similar to that obtained with other predictive methods. With regard to the faecal spectra (second derivative mode), the fat absorbency at wavelengths of 1730, 2310 and 2350 nm was higher when the corresponding forage was highly digestible and ingestible.In conclusion, applying NIRS to faeces is a rapid and easy analytical method that could be an interesting tool for managing grazing ruminants and optimising their performance.     

Polyethylene glycol compared with ytterbium oxide as a total faecal output marker to predict organic matter intake of dairy ewes fed indoors or at pasture

Several external markers can be used for estimating total faecal output in view of assessing ruminant intake at pasture. Among them, ytterbium (Yb) has been used for many years in various conditions. Polyethylene glycol (PEG) is a promising external marker because it can be rapidly determined using near-infrared spectroscopy (NIRS). The study consisted of 24 adult lactating dairy ewes over three periods (P1, P2 and P3), fed with three different diets: P1, total mixed ration (TMR); P2, Italian ryegrass (IRG); and P3, pasture. After an adaptation period, the ewes were administered a daily dose of ytterbium oxide (0.35 g/day) and PEG (20 g/day) for 2 weeks. During the last week, the daily organic matter intake (OMI_OBS) was measured. Faecal samples were collected at milking time (0800 and 1600 h) to determine marker content, using only samples collected in the morning (PEG_m) or by averaging samples (Yb, PEG_ma). Faecal marker content made it possible to assess total faecal output, either using the two recovery rates for PEG (0.98 or 0.87) or not. The OMI_OBS was assessed on the basis of total faeces estimated with Yb (OMI_Yb) or PEG (OMI_PEG), and the digestibility was calculated on the basis of feed analysis. With total TMR (P1), the OMI_PEG, corrected with recovery rate (OMI_PEGm98) or not corrected (OMI_PEGm) was 2.40 kg/day and 2.50 kg/day, respectively, and was not different (P>0.05) from OMI_OBS (2.51 kg/day), whereas OMI_Yb was lower (2.14 kg/day) (P<0.001). With IRG (P2), OMI_PEGm98 (1.67 kg/day), OMI_PEGm87 (1.51 kg/day) and OMI_Yb (1.59 kg/day) were not different (P>0.05) from OMI_OBS (1.57 kg/day). With pasture (P3), the OMI_PEGm (1.54 kg/day) and OMI_PEGm98 (1.48 kg/day) were not different (P>0.05) from the OMI assessed from the biomass measurement (1.52 kg/day). The OMI_Yb (1.36 kg/day) was lower (P<0.05) but not different from OMI_PEGm98 and OMI_PEGm87. Spearman’s rank correlation between OMI_OBS and other OMIs (predicted with Yb or PEG P1 and P2) showed that it is possible to rank animals using PEG when there is a sufficiently wide range of OMI_OBS (1.65 to 2.8 kg/day in P1) but not within a narrower range (1.47 to 1.72 kg/day in P2). In conclusion, the present study confirms that PEG is a valuable external faecal marker, easy to prepare (solution), administer and determine (NIRS). It can be used to assess intake with numerous animals at pasture, but only for groups, and not to quantitatively estimate individual OMI.     

Curcumin prevents Cr(VI)-induced renal oxidant damage by a mitochondrial pathway

We report the role of mitochondria in the protective effects of curcumin, a well-known direct and indirect antioxidant, against the renal oxidant damage induced by the hexavalent chromium [Cr(VI)] compound potassium dichromate (K₂Cr₂O₇) in rats. Curcumin was given daily by gavage using three different schemes: (1) complete treatment (100, 200, and 400 mg/kg bw 10 days before and 2 days after K₂Cr₂O₇ injection), (2) pretreatment (400 mg/kg bw for 10 days before K₂Cr₂O₇ injection), and (3) posttreatment (400 mg/kg bw 2 days after K₂Cr₂O₇ injection). Rats were sacrificed 48 h later after a single K₂Cr₂O₇ injection (15 mg/kg, sc) to evaluate renal and mitochondrial function and oxidant stress. Curcumin treatment (schemes 1 and 2) attenuated K₂Cr₂O₇-induced renal dysfunction, histological damage, oxidant stress, and the decrease in antioxidant enzyme activity both in kidney tissue and in mitochondria. Curcumin pretreatment attenuated K₂Cr₂O₇-induced mitochondrial dysfunction (alterations in oxygen consumption, ATP content, calcium retention, and mitochondrial membrane potential and decreased activity of complexes I, II, II-III, and V) but was unable to modify renal and mitochondrial Cr(VI) content or to chelate chromium. Curcumin posttreatment was unable to prevent K₂Cr₂O₇-induced renal dysfunction. In further experiments performed in curcumin (400 mg/kg)-pretreated rats it was found that this antioxidant accumulated in kidney and activated Nrf2 at the time when K₂Cr₂O₇ was injected, suggesting that both direct and indirect antioxidant effects are involved in the protective effects of curcumin. These findings suggest that the preservation of mitochondrial function plays a key role in the protective effects of curcumin pretreatment against K₂Cr₂O₇-induced renal oxidant damage.     

Biotransformation of hexavalent chromium into extracellular chromium(III) oxide nanoparticles using <Emphasis Type="Italic">Schwanniomyces occidentalis</Emphasis>

Objectives

To demonstrate biotransformation of toxic Cr(VI) ions into Cr₂O₃ nanoparticles by the yeast Schwanniomyces occidentalis.

Results

Reaction mixtures containing S. occidentalis NCIM 3459 and Cr(VI) ions that were initially yellow turned green after 48 h incubation. The coloration was due to the synthesis of chromium (III) oxide nanoparticles (Cr₂O₃NPs). UV–Visible spectra of the reaction mixtures showed peaks at 445 and 600 nm indicating ⁴A_2g → ⁴T_1g and ⁴A_2g → ⁴T_2g transitions in Cr₂O₃, respectively. FTIR profiles suggested the involvement of carboxyl and amide groups in nanoparticle synthesis and stabilization. The Cr₂O₃NPs ranged between 10 and 60 nm. Their crystalline nature was evident from the selective area electron diffraction and X-ray diffraction patterns. Energy dispersive spectra confirmed the chemical composition of the nanoparticles. These biogenic nanoparticles could find applications in different fields.

Conclusions

S. occidentalis mediated biotransformation of toxic Cr(VI) ions into crystalline extracellular Cr₂O₃NPs under benign conditions.

     

Organic matter digestibility of condensed tannin-containing Lotus corniculatus and its prediction in vitro using cellulase/hemicellulase enzymes

Three digestion experiments involving cryptorchid weaned lambs were conducted for 14-day periods in the spring, summer and autumn to determine the in vivo digestibility of dry matter (DMD), gross energy (GE), organic matter (OMD), digestible organic matter in the dry matter (DOMD) and estimated metabolisable energy (ME) concentration of Lotus corniculatus L. (birdsfoot trefoil; cv. Grasslands Goldie) at different stages of maturity. The experiments were carried out indoors at Massey University's Riverside farm, in the Wairarapa, North Island, New Zealand. In vivo digestibility samples were then used as standards to investigate if the enzymic in vitro system of [Roughan, P.G., Holland, R., 1977. Predicting in vitro digestiblities of herbages by exhaustive enzymic hydrolysis of cell walls. J. Sci. Food Agric. 28, 1057–1064] could predict OMD and DOMD of condensed tannin (CT)-containing L. corniculatus.Digestibility of L. corniculatus declined as it matured, but the rate of decline was much less than that which occurs for perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pasture. It was concluded that the in vitro enzymic system of [Roughan, P.G., Holland, R., 1977. Predicting in vitro digestiblities of herbages by exhaustive enzymic hydrolysis of cell walls. J. Sci. Food Agric. 28, 1057–1064] can be used to predict OMD and DOMD of L. corniculatus with a high degree of accuracy, provided a standard curve involving in vivo data generated with L. corniculatus is used. Using a standard curve with in vivo data from perennial ryegrass/white clover pasture led to bias which increased at lower OMD values. Reasons for the differences between L. corniculatus and pasture standard curves are discussed, including possible effects of bound CT.