Search

Markers of liquid digesta are an essential tool for determination of in vivo nutrient digestibility and passage as they move with and mark passage of the liquid fraction through the gut. Such markers are ideally biologically and chemically unreactive so they do not affect the digesta or animal. Two issues encountered with the liquid marker chromium (III) (Cr) ethylenediaminetetraacetic acid (EDTA; Cr-EDTA): 1) the Cr acetate·monohydrate required for preparation of the crystallized lithium salt of Cr-EDTA (Li·Cr-EDTA; Uden method; J. Sci. Food Agric. 31, 1980, 625–632) has become largely unavailable, and 2) as an ionic salt, the degree of complexation of Cr and EDTA in solution of an uncrystallized preparation of Cr-EDTA has not been evaluated. Accordingly, the objectives of this study were to develop a method for preparing Li·Cr-EDTA using Cr (III) acetate hydroxide, and to compare the degree to which Cr is complexed with EDTA in solutions made with crystallized Li·Cr-EDTA and in preparations in which Cr-EDTA is not crystallized for purification (Binnerts method; Vet. Rec. 82, 1968. 470). The new Li·Cr-EDTA preparation method which uses Cr acetate hydroxide gave product yields of 901 to 870 g actual/kg theoretical which was similar to the 900 g actual/kg theoretical yield reported for the original Uden method. The Cr concentrations were 928–961 g actual/kg theoretical for the salt. Solutions of both the crystallized preparation of Li·Cr-EDTA and the liquid preparation of the Binnerts method gave visibly similar absorbance patterns at wavelengths from 300 to 750 nm and showed maximum light absorption at 541 nm, the reported wavelength of maximum absorption for Cr-EDTA. Comparison of absorbances at 541 nm to a Li·Cr-EDTA generated standard curve showed that uncrystallized Cr-EDTA produced with the Binnerts method gave a recovery of Cr in Cr-EDTA of approximately 993 g/kg, which did not differ from the 992 g/kg value for preparations of Li·Cr-EDTA; this indicates that Cr and EDTA for both preparation methods were almost completely complexed in solution. In conclusion, the new method for preparing Li·Cr-EDTA gave results comparable to the Uden method, and Cr and EDTA were ionically bound to a high degree and comparably in both the uncrystallized solution of the Binnerts method and solutions of crystallized Li·Cr-EDTA. Verification of the degree of Cr and EDTA complexation in Binnerts preparations can be accomplished with spectrophotometric comparison against a purified standard such as Li·Cr-EDTA.

Pretreatment of biomass feedstocks is considered necessary to increase their conversion to biofuels and other bioproducts. However, even the best chemical and physical pretreatments have disadvantages that make the development of alternative strategies to improve biomass fermentability a worthy pursuit. An interesting natural process is that of rumination, by which ruminant animals regurgitate their food for re-chewing to reduce particle size, increase surface area, and accelerate its biodegradation by the animal's mutualistic microbial community. Detailed examination of the process reveals that it is a unique, unusually effective, and energy-efficient type of physical treatment of fibrous biomass. Effectiveness and energy efficiency are gained by several unappreciated aspects of the process, including: full wetting of the biomass prior to its exposure to re-chewing; a hypsodont dentition pattern and jaw movement designed to maximize shearing and delamination (rather than cutting) of the biomass; and an effective feed sorting mechanism that results in a preferential processing of the larger particles that are in need of further grinding, rather than smaller particles whose additional grinding would provide little benefit. These nuances of the rumination process suggest designs for accomplishing similar particle size reduction and surface area increases within bioreactors during cellulosic biomass fermentation (“co-treatment”). While the rumination process has evolved within the context of allowing the ruminant animal to exploit widely available but highly fibrous feeds, it has the potential for broad applicability and improved efficiency for industrial conversion of cellulosic biomass by both pure and mixed cultures.

Neutral detergent fiber digestibility (NDFD) determined in vitro with rumen inoculum is widely used to assess digestibility and potential energy contributions of feedstuffs. An in vitro fermentation system (IVFS) with potential to improve sample throughput and ease of handling for NDFD determination was investigated. Additionally, methods for preparing high moisture forages and their effect on in vitro NDFD were evaluated. In the IVFS study, a commonly used method that uses Erlenmeyer flasks under continuous CO 2 pressure in water baths (GV) was compared to a system that uses sealed glass tubes in a shaking incubator (TU). Fibrous feeds (alfalfa hay, maize silage, soyhulls, and ryegrass hay) were incubated in duplicate for 24, 30, and 48 h in three fermentation runs (run) in both IVFS. Overall, NDFD was greater for TU than GV at 24 h, and greater for GV than TU at 48 h. Maize silage had lower values with TU than GV, with the difference increasing with fermentation time, possibly due to low pH related to amount of fermentable substrate used. Within-run variability at 48 h was less with GV than TU. Variability of NDFD across runs was or tended to be less for TU at 24 and 30 h, and tended to be less for GV at 48 h. In the forage processing study, silages (alfalfa, maize) and pasture grasses (meadow fescue, orchardgrass, reed canarygrass, ryegrass) were ground with dry ice through a meat grinder to pass 4.5 mm openings. Subsamples were dried in a 55 °C forced-air oven (OD), freeze dried (FD), or retained as undried frozen (UF) material. Samples were fermented in duplicate in TU for 24, 30, and 48 h in two runs. NDFD response to processing varied by forage with FD for orchardgrass and UF for maize silage lower than other treatments for those forages. Overall, NDFD did not differ among processing methods at 24 h, was greatest for OD and UF at 30 h, and for OD at 48 h. Based on NDFD and analytical variability results, TU may be recommended at 24 and 30 h and GV at 48 h, however, substrate amount may need to be restricted in TU to avoid depressing NDFD. Methods of processing high moisture forage samples for NDFD analysis showed no clear advantage for using freeze dried or undried forage over oven dried materials.

Reducing sugar (RSA) and phenol–sulfuric acid (PSA) assays are commonly used to analyze water-soluble carbohydrates. However, questions have arisen as to their accuracy for measurements of feedstuffs with diverse carbohydrate profiles. This study evaluated the efficacy of RSA and PSA as they would commonly be applied in feed analysis laboratories in measuring a variety of purified carbohydrates. Carbohydrates analyzed were glucose (Glc), fructose (Fru), galactose (Gal), sucrose (Suc), maltose (Mal), lactose (Lac), raffinose (Raf), and inulin (Inu). Variations on the methods used were PSA using Suc (PSA-Suc) or Glc (PSA-Glc) as standard sugars, and RSA with a 50:50 Glc:Fru blend as the standard with four hydrolysis methods: acid hydrolysis with 0.037 M sulfuric acid (RSA-H2SO4) or 0.5 M hydrochloric acid (RSA-HCl), or enzymatic hydrolysis with invertase (RSA-Inv) or an enzyme blend including sucrase, α-glucosidase, and β-galactosidase (RSA-EnzBl). Recovery of carbohydrate was calculated on a dry matter (DM) basis as (carbohydrate detected g/kg DM)/(carbohydrate present kg/kg DM), with ‘close to’ complete recovery defined as values falling within the range of 920–1080 g/kg. Monosaccharide recovery did not differ between unhydrolyzed vs. hydrolyzed samples in RSA indicating no destruction of carbohydrate by hydrolysis method. For RSA, recoveries of Glc, Fru, and Gal were 979, 1042, and 706 g/kg, respectively. Such response differences among monosaccharides are inherent to RSA, and can affect carbohydrate recovery values. Methods that provided close to complete recovery by carbohydrate were: PSA-Suc and all RSA for Suc; PSA-Glc and RSA-EnzBl for Mal and Lac; PSA-Suc, RSA-H2SO4, RSA-HCl, and RSA-Inv for Raf; and RSA-H2SO4 and RS-HCl for Inu. None of the assays gave complete recovery of the diverse set of purified carbohydrates. Allowing a range of 920–1080 g/kg for recoveries on individual carbohydrates, RSA-H2SO4 and RSA-HCl would give the closest to complete recovery values for feeds such as forage and soybean in which Suc, Raf, and Inu were important, whereas RSA-EnzBl would be useful in feeds such as forages or dairy products when Suc, Mal, and Lac are of interest. The allowed 920–1080 g/kg range of acceptable recoveries addresses the point that given very diverse carbohydrate complements of feeds, these assays will not be extremely precise, but may still be serviceable for diet formulation. The most accurate measurements will be achieved by selection of detection method, hydrolysis method, and carbohydrate standard to give greatest recovery of predominant carbohydrates in feedstuffs.

Volatile fatty acid concentrations ([VFA], mM) have long been used to assess the effect of dietary treatments on ruminal fermentation in vivo. However, discrepancies in statistical results between [VFA] and VFA pool size (VFAmol) possibly related to ruminal digesta liquid amount (LIQ, kg) indicate potential issues with the use of [VFA]. We investigated relationships among [VFA], VFAmol, and LIQ measured 2 h postfeeding using individual lactating cow data (n=175) from 7 separate feeding studies. Regression analyses were performed using mixed models with "study" as a discrete random variable. The mean across studies and average range of values within studies, respectively, were 151 and 75 for [VFA], 11.2 and 9.8 for VFAmol, 73.3 and 41.0 for LIQ, and 289 and 83 mmol/kg for rumen fluid osmolality. Liquid amount changed with VFAmol (3.76 VFAmol+31.2; average within-study R2=0.69), but the relationship was weak between [VFA] and LIQ (0.524 LIQ+112.8; average within-study R2=0.12). The relationship between LIQ and VFAmol was likely a function of the osmotic gradient between rumen liquid and blood. The VFA are a major ruminal solute; VFAmol amounts can affect water flux in the rumen as similar tonicities of rumen fluid and blood are maintained. This also has a damping effect on ruminal solute concentration, creating the weak relationship between [VFA] and LIQ. Within studies, similar [VFA] were found in LIQ differing by 30 kg or more. The difference between minimum and maximum LIQ within cow within study was 12.7 kg (standard deviation=7.1), so inclusion of "cow" in analyses did not correct for the variation in LIQ. To allow valid comparisons of experimental treatments, responses must be on an equivalent basis; concentrations in different LIQ are not on an equivalent basis and so are not valid to use for comparing treatment effects. The [VFA] changed with VFAmol (5.80 VFAmol+86.3; average within-study R2=0.56). However, the ratio of [VFA] to VFAmol ranged from 9.0 to 24.1 as a function of 1,000/LIQ; this reflects the inherent calculated relationship among the variables. The varying relationship of [VFA] to VFAmol further indicates that [VFA] is not an appropriate measure to evaluate the progress or effect of treatments on ruminal fermentation. Predictions of LIQ and VFAmol using cow and ruminal measures were insufficiently precise to be used in research. Previously drawn conclusions based on [VFA] need to be reevaluated, and alternate evaluations for in vivo ruminal fermentation are needed.

Groat per cent and milling yield are important quality traits of oat (Avena sativa L.); however, accurate testing for these traits using existing methods can be time-consuming and labour-intensive. In this study digital imaging analysis (DIA) was used to estimate the mass of mechanically dehulled oat constituents (hulls, undamaged and broken groats), replacing hand sorting and weighing of these constituents in a test method measuring groat per cent and milling yield. Groat per cent values estimated using DIA had a standard error of prediction (SEP) of 0·57 and a correlation coefficient of 0·995 compared to the manual method. Milling yield values estimated using DIA had a SEP of 0·98 and a correlation coefficient of 0·993 compared to the manual method. Incorporating DIA into the test method allowed considerable savings of time and labour in performing these tests.

A new method for determining neutral detergent-soluble fiber (NDSF) estimates the non-starch polysaccharide present in 90% ethanol-insoluble residue (EIR) but absent from neutral detergent residue (NDF). Unextracted feeds, EIR and NDF of feeds high in pectic substances were fermented in vitro with mixed ruminal microbes and gas production was measured. Soybean hulls were fermented for 48 h, and all other feeds for 24 h. Fermentation kinetics of NDSF were determined from gas curves produced by point by point subtraction of the gas production curves of NDF from those of EIR. Single-pool logistic fermentation rates and lag times for NDSF and NDF were determined from the gas production data. The single-pool logistic rates for NDSF for dried citrus pulp, dried beet pulp, soybean hulls, mature alfalfa stems and leaves and immature alfalfa stems and leaves were 0.13, 0.16, 0.05, 0.11, 0.14, 0.18 and 0.13 h−1, respectively. Fermentation rates tended to be faster and lag times shorter for NDSF than for NDF. Acetate to propionate ratios were numerically higher for EIR fermentations than for unextracted feeds or NDF. The fermentation characteristics of NDSF for the feeds in this study are consistent with reports of pectic substance fermentations indicating that NDSF does describe the soluble fiber fraction. The NDSF and gas production measurement methods offer nutritionally relevant ways to estimate soluble fiber content and its digestion characteristics in feedstuffs.

Dose-rate effects were measured for typical ethylene propylene rubber (EPR) and crosslinked polyethylene (XLPE) electric cable used in nuclear power plants. The radiation source was the 60 Co Irradiation Facility at the University of Virginia. Dose rates were varied from 5 Gy/h to 2500 Gy/h. It was found that there is little or no dose-rate effect at low doses for four of the five EPR cable products tested from 2500 Gy/h down to dose rates of 5 Gy/h but perhaps a small dose-rate effect at high doses for dose rates above 340 Gy/h. A small dose-rate exists for the fifth EPR above 340 Gy/h at all doses. A dose-rate effect exists above 40 Gy/h for two of the three XLPE cable products tested, but there is no dose-rate for these XLPE's between 40 Gy/h and 5 Gy/h. These results indicate that the dose-rate effects observed are due to oxygen diffusion effects during heterogeneous aging and suggest that there is no dose-rate effect for either EPR or XLPE during homogeneous aging.

In an effort to maintain the height of the residual alveolar ridge, Bioglass cones were placed in fresh sockets after tooth extraction. Today the emphasis is on maintaining the residual alveolar ridge instead of letting it resorb and subsequently resorting to heroic efforts for augmentation. To date, 242 cone implants have been placed in 29 patients. Implant follow-up observation time ranged from 12 to 32 months with an average of 19.9 months. Twenty-seven patients have been fitted with dentures. To date seven implants (2.9%) have been lost. The Bioglass implants appear to be highly biocompatible as evidenced by absence of infection, normal mucosal healing, and radiographic evidence of bone healing around the implants. Evaluation of several implants reexposed surgically revealed new bone in direct contact with the immobile implants circumferentially. The problem of implant dehiscence that started to occur after approximately 10 months in other investigations had not manifested itself in the Bioglass implant patients who have been wearing their dentures for at least 12 months.