P997Improving left atrial appendage occluder size determination by using 3-dimensional printing model of the left atrial appendage

Introduction

Given the complexity of left atrial appendage (LAA) structure, current 2D based LAA occluder (LAAO) size prediction system using transesophageal echocardiography (TEE) has limitations.

Objective

To assess the accuracy of LAAO size determination method by implantation simulation using a 3D printed model compared with a conventional method based on TEE.

Methods

We retrospectively reviewed 57 cases with percutaneous LAAO using Amplatzer Cardiac Plug and Amulet from 2014 to 2018. We excluded cases without cardiac CT (21 cases) or with peri-device leakage or inappropriate position of the device on six months follow up TEE (6 cases), or with paroxysmal atrial fibrillation (2 cases). We finally included 28 cases with anatomically and physiologically properly implanted LAAO, using the final size of the implanted devices as a standard for the size prediction accuracy. We generated 3D printing model from cardiac CT images. LAAO size was determined with device implantation simulation using 3D printing model and occluder devices (Figure C), and conventional 2D TEE measurements by two experienced cardiologists who were blinded to the size of the finally implanted device.

Results

The accuracy in size of 3D printed left atrium (LA) models, compared with CT image sources, were validated by measuring the distance between artifacts which were intentionally implanted to LA model during image processing. There was minimal bias (−0.11 mm) between 3D images and printed LA models (Figure A). As plotted in Figure B, LAAO sizing by implantation simulation with 3D printing model showed excellent agreement with actually implanted LAAO size (r=0.927; bias=0.7±2.5), while LAAO sizing by 2D TEE measurements remained poor (r=0.544; bias 2.3±6.7).

Conclusions

LAAO size determination by using 3D printing model of LAA showed excellent accuracy. A prospective study to evaluate the clinical utility of this method should be done in future.

P604Clinical feasibility assessment of a novel Quantitative Multi-contrast Atherosclerosis Characterization (qMATCH) sequence for carotid plaque quantification

Background

Conventional protocol contrast MRI (cMRI) for evaluating carotid artery atherosclerosis is clinically under-utilized due to complex scanning procedures and long scan time. Recently, the Quantitative Multi-contrast Atherosclerosis Characterization (qMATCH) has been proposed, which allows comprehensive and quantitative assessment of atherosclerosis including MRA, dark-blood vessel wall morphology, and T1/T2 mapping with an 8-minute single scan (Figure1). However, the diagnostic accuracy and feasibility of qMATCH has not been validated in clinical circumstances.

Purpose

To evaluate the diagnostic accuracy of quantitative plaque analysis of qMATCH compared with cMRI

Method

We prospectively enrolled 43 patients who have carotid plaques diagnosed by carotid ultrasound. cMRI was performed along with qMATCH scan. All imaging data were acquired with a clinical 3T scanner using a 64-channel head & neck coil. In the current analysis, we evaluated the diagnostic accuracy of qMATCH in the quantitative assessment of carotid plaque. Plaque area measurements using dark-blood wall images with qMATCH were compared with corresponding cross-sectional T1/T2-weighted images with cMRI as references values (Figure 2). These inter-technique comparisons included linear regression with Pearson correlation and Bland-Altman analyses to assess the mean inter-technique differences (biases) and limits of agreements.

Result

Among 90 segments, mean plaque areas measured by cMRI and qMATCH were 43.83±21.21 mm2 and 42.47±19.23mm2, respectively (mean differences, −1.36±8.12mm2; p for a paired t-test, 0.073). Correlation coefficient showed excellent correlation between plaque areas measured by cMRI and qMATCH (r=0.943, p<0.001) (Figure 3). Bland-Altman plot showed excellent agreement in plaque areas between the two methods (Figure 4).

Conclusion

Quantitative carotid plaque burden analysis by a novel sequence with qMATCH is feasible and accurate compared with conventional MRI. Given that qMATCH can reduce scan time and allow quantitative relaxometry mapping, fast and accurate carotid plaque analysis would be feasible. Further studies to evaluate the accuracy of qualitative plaque analysis should be performed to confirm the “all-in-one” assessment of carotid atherosclerosis using qMATCH.

[Cost estimation for hospital mass casualty exercises]

A mass casualty event (MCE) poses an enormous challenge for rescue services and hospitals. In addition to a hospital emergency plan, employee training and practice exercises are essential to be prepared for such an event. The organizational and financial burden of MCE exercises in a hospital is extraordinarily high. In a retrospective analysis of several large hospital exercises, the magnitude of the necessary financial means for the preparation and execution of such drills is outlined. Depending on the size (number of patients) and scope (extent of departments involved) of the MCE exercise in a hospital, a full-size MCE drill may entail costs between 10,000 and 100,000€. Since the execution of such exercises is essential in the sense of preparedness and considering quality management aspects, possibilities of refinancing and more cost-efficient training must be developed.

[Web-based evidence of treatment capacity. An instrument for optimizing the interface between prehospital and hospital management]

BACKGROUND

The outcome of injured patients depends on intrastractural circumstances as well as on the time until clinical treatment begins. A rapid patient allocation can only be achieved occur if informations about the care capacity status of the medical centers are available. Considering this an improvement at the interface prehospital/clinical care seems possible.

MATERIAL AND METHOD

In 2010 in Frankfurt am Main the announcement of free capacity (positive proof) was converted to a web-based negative proof of interdisciplinary care capacities. So-called closings are indicated in a web portal, recorded centrally and registered at the local health authority and the management of participating hospitals.

RESULTS

Analyses of the allocations to hospitals of all professional disciplines from the years 2009 and 2010 showed an optimized use of the resources. A decline of the allocations by the order from 261 to 0 could be reached by the introduction of the clear care capacity proof system. The health authorities as the regulating body rarely had to intervene (decline from 400 to 7 cases). Surgical care in Frankfurt was guaranteed at any time by one of the large medical centers.

CONCLUSION

The web-based care capacity proof system introduced in 2010 does justice to the demand for optimum resource use on-line. Integration of this allocation system into the developing trauma networks can optimize the process for a quick and high quality care of severely injured patients. It opens new approaches to improve allocation of high numbers of casualties in disaster medicine.

Effect of reduced ferulate-mediated lignin/arabinoxylan cross-linking in corn silage on feed intake, digestibility, and milk production

Cross-linking of lignin to arabinoxylan by ferulates limits in vitro rumen digestibility of grass cell walls. The effect of ferulate cross-linking on dry matter intake (DMI), milk production, and in vivo digestibility was investigated in ad libitum and restricted-intake digestion trials with lambs, and in a dairy cow performance trial using the low-ferulate sfe corn mutant. Silages of 5 inbred corn lines were fed: W23, 2 W23sfe lines (M04-4 and M04-21), B73, and B73bm3. As expected, the W23sfe silages contained fewer ferulate ether cross-links and B73bm3 silage had a lower lignin concentration than the respective genetic controls. Silages were fed as the sole ingredient to 4 lambs per silage treatment. Lambs were confined to metabolism crates and fed ad libitum for a 12-d adaptation period followed by a 5-d collection period of feed refusals and feces. Immediately following the ad libitum feeding trial, silage offered was limited to 2% of body weight. After a 2-d adaptation to restricted feeding, feed refusals and feces were collected for 5 d. Seventy Holstein cows were blocked by lactation, days in milk, body weight, and milk production and assigned to total mixed ration diets based on the 5 corn silages. Diets were fed for 28 d and data were collected on weekly DMI and milk production and composition. Fecal grab samples were collected during the last week of the lactation trial for estimation of feed digestibility using acid-insoluble ash as a marker. Silage, total mixed ration, feed refusals, and fecal samples were analyzed for crude protein, starch, neutral detergent fiber (NDF), cell wall polysaccharides, and lignin. The W23sfe silages resulted in lower DMI in the ad libitum trial than the W23 silage, but DMI did not differ in the restricted trial. No differences were observed for NDF or cell wall polysaccharide digestibility by lambs with restricted feeding, but the amount of NDF digested daily increased for lambs fed the M04-21 W23sfe silage ad libitum. Lambs were less selective against NDF and lignin when offered W23sfe silages. The B73bm3 silage did not affect DMI or digestibility of cell walls at the restricted feeding level, but total daily NDF digested was greater at ad libitum intake. Intake, milk production, and cell wall digestibility were greater for cows fed diets containing W23sfe silages than for those fed W23 silage. Although milk production was greater for the B73bm3 diet, DMI and cell wall digestibility were not altered. Cows were less selective against cell wall material when fed both W23sfe and B73bm3 silages. Reduced ferulate cross-linking in sfe corn silage is a new genetic mechanism for improving milk production.

Effect of Direct-Fed Microbials on Performance, Diet Digestibility, and Rumen Characteristics of Holstein Dairy Cows

The objective of this study was to determine the effect of feeding direct-fed microbial (DFM) products containing Lactobacillus acidophilus and Propionibacteria freudenreichii on the performance, nutrient digestibility, and rumen fermentation of Holstein dairy cows in midlactation. Experiments were conducted from February to May 2003. Cows were fed 1 of 3 dietary treatments: 1) 1 x 10(9) colony-forming units (cfu)/d of live L. acidophilus strain LA747 and 2 x 10(9) cfu/d of live P. freudenreichii strain PF24 (DFM1); 2) 1 x 10(9) cfu/d of live L. acidophilus strain LA747, 2 x 10(9) cfu/d of live P. freudenreichii strain PF24, and 5 x 10(8) cfu/d of L. acidophilus strain LA45 (DFM2); or 3) lactose (control). Treatments were administered by mixing 45 g of finely ground corn with 5 g of DFM products or lactose and top dressing on the total mixed rations once daily. All cows received the same total mixed ration: 12.7% alfalfa hay, 46.2% corn silage, and 41.1% concentrate on a dry matter (DM) basis. In study 1 (lactation study), 39 multiparous and 18 primiparous Holstein cows were blocked by parity and randomly assigned to treatments for 84 d. Starting on d 35, fecal grab samples were collected from each cow at 5- to 8-h intervals over 48 h for digestibility measurements. A rumen fermentation study (study 2) was conducted concurrently with the lactation study. Three rumenfistulated, multiparous Holstein cows were randomly assigned to dietary treatments DFM1, DFM2, and control in a 3 x 3 Latin square design with 28-d periods. In study 1, there was no difference in average DM intake (23.9, 23.6, and 24.2 kg/d) or 4% fat-corrected milk (36.8, 35.3, and 36.2 kg/d) for treatments DFM1, DFM2, and control. Percentage or yield of milk components also did not differ among treatments. Feed efficiency averaged 1.52 kg of 4% fat-corrected milk/kg of DM intake and did not differ among treatments. There were no differences in apparent DM, crude protein, neutral detergent fiber, or starch digestibility among treatments. In study 2, there was no difference in rumen pH and concentrations of ammonia or total volatile fatty acids measured at 0, 1, 3, and 6 h after feeding. Under the conditions of these studies, supplementing midlactation cows with DFM products containing L. acidophilus and P. freudenreichii did not affect cow performance, diet digestibility, or rumen fermentation.

Comparison of feeding corn silages from leafy or conventional corn hybrids to lactating dairy cows

Three corn hybrids (Pioneer 36F30, Mycogen TMF2450, and Mycogen TMF2404) were compared for yield and quality traits, and lactation performance and apparent digestibility by Holstein cows. The three corn silages were harvested at a target of 33 to 35% dry matter. Before harvest, six corn plants were randomly selected for plant fractionation. Grain-to-stover ratios were 0.92, 0.70, and 0.95 for the 36F30, TMF2450, and TMF2404 corn plants, respectively. Fifty-two multiparous Holstein cows were placed on a 120-d lactation trial after a 21-d covariate diet. Cows were blocked by calving date and randomly assigned within block to one of three dietary treatments, containing approximately 40% (dry matter basis) corn silage. Milk yield, milk components, and dry matter intake did not differ among dietary treatments. In vitro true and neutral detergent fiber digestibilities were numerically higher for TMF2404 than the other corn silage hybrids. Apparent total-tract crude protein and neutral detergent fiber digestibilities, as measured by acid insoluble ash, were higher for TMF2450 than the other two hybrids, but starch digestibility was not different between the corn silage dietary treatments. Although small differences in nutrient content and digestibility existed among corn silage hybrids, inclusion of these leafy hybrids in lactating cow diets at 40% of the dietary dry matter did not have a significant impact on lactation performance of dairy cattle.

Results of neurilemoma treatment: a review of 78 cases

Between 1984 and 1994, a total of 78 patients underwent surgery for neurilemoma of the trunk or extremities. The incidence according to the involved nerve was analyzed and the follow-up results and complications after surgical treatment were reviewed. The median nerve was most frequently involved among 15 different nerves. Marginal excision was performed in 70 (90%) patients, incisional biopsy in 6 (8%), and wide excision in 2 (2%). Postoperative complications were paresthesia in 7 patients. There was no recurrence or malignant transformation until the average 47 months of follow-up. In most patients, marginal excision was sufficient to prevent local recurrence and did not impair nerve function significantly.

Effect of feeding silages from corn hybrids selected for leafiness or grain to lactating dairy cattle

Three corn hybrids were harvested as silage and fed to lactating dairy cows to determine performance and digestibility differences between hybrids. Corn hybrids were a grain type, a generic blend, and a leafy type. Starch content of the grain, blend, and leafy silage hybrids was 26.1, 23.8, and 23.5%, respectively. In vitro digestible dry matter of the leafy hybrid silage (69.2%) was higher than the grain (66.8%) or blend (66.7%) hybrid silage. Sixty-two Holstein cows (39 primiparous and 23 multiparous) were fed diets containing (dry matter basis) 40.6% of one of the corn silages, 10.2% alfalfa haylage, 23.5% corn grain, 7.4% whole-fuzzy cotton-seed, 13.8% protein concentrate, and 4.5% vitamin and mineral mix. Cows were assigned to their silage treatment diet 3 d after parturition and remained on the diet until wk 22 of lactation. Dry matter intake, milk yield, and milk components did not differ for cows fed the grain, leafy, or generic blend silage diets for either parity group. Digestibilities of dry matter, organic matter, and neutral detergent fiber, and rate of passage were not different across the silage diets for either parity. Multiparous cows receiving the blend silage diet lost more weight throughout the 22-wk study than did cows on the leafy or grain silage diets. Primiparous cows receiving the blend silage diet spent more time eating than cows on either the grain or leafy silage diet. Time spent chewing did not differ among hybrids. Corn hybrid at 40% of dietary dry matter as silage did not have a major impact on dairy cattle performance in this trial.

Effects of type of carbohydrate supplementation to lush pasture on microbial fermentation in continuous culture

Eight single-flow continuous culture fermenters were used to study the effects of the type of energy source on ruminal N utilization from high quality pasture. The four dietary treatments included high quality grass and legume pasture alone (50:50; wt/wt), pasture plus soybean hulls, pasture plus beet pulp, and pasture plus corn. Diets supplemented with additional sources of energy (soybean hulls, beet pulp, and corn) were isocaloric but differed in the type and rate of carbohydrate fermentation. Energy supplements constituted 45% of the total dietary dry matter and were fed twice daily at 12-h intervals in place of pasture, which is characteristic of grain feeding at milking when animals are in a grazing situation. Energy supplementation reduced pH, NH3 N flow, and NH3 N concentration and increased bacterial N flow (as a percentage of N intake). The supplementation of corn and soybean hulls resulted in the highest microbial N flow (as a percentage of N intake). Corn had a tendency to reduce fiber digestion because of excessively low NH3 N concentrations. Beet pulp was similar to corn in that it decreased NH3 N concentrations. Supplementation of soybean hulls resulted in a more synchronized fermentation, greater volatile fatty acid production, and greater fiber digestion. Nitrogen utilization by microbes was maximized by supplementation with soybean hulls or corn twice a day. With diets based on pasture, it may be more important to improve bacterial N flow and bacterial utilization of N than to maximize the efficiency of bacterial protein synthesis because better utilization of N by ruminal microorganisms results in higher bacterial N flow and higher fiber digestion.

Wound response characteristics as related to phenylpropanoid enzyme activity and lignin deposition in resistant and susceptible Populus tremuloides inoculated with Entoleuca mammata (Hypoxylon mammatum)

Green internodal stem tissues of glasshouse grown Populus tremuloides were either wounded or wound-inoculated with Entoleuca mammata (Hypoxylon mammatum) and assayed for phenylalanine ammonia-lyase (PAL), caffeic acid - o-methyltransferase (CA-OMT), and cinnamyl - alcohol dehydrogenase (CAD) activity over a 96-h period. Lignin deposited in response to the treatments was analyzed by the Klason and the pyrolysis - gas chromatographic (GC) - mass spectroscopy (MS) methodologies. The wound-inoculated treatment resulted in a wound morphology congruent with a typical resistant and susceptible response to E. mammata. Wounding alone resulted in no morphological differences between the two genotypes. In wound-inoculated stem tissue PAL and CAD activities were substantially higher in the resistant relative to the susceptible genotype. Total Klason lignin was similar for both genotypes; however, pyrolysis-GC-MS analysis revealed a difference in the lignin monomeric composition between the two genotypes, with the susceptible genotype accumulating higher levels of hydroxyphenyl units relative to the resistant genotype. It is concluded that differences in PAL and CAD activity and the synthesis of distinct phenylpropanoid monomers distinguish the resistant from the susceptible aspen genotype. Alterations in boundary zone formation due to the differential synthesis of phenylpropanoid monomers and its effect on compartmentalization of the pathogen are discussed.Key words: aspen, Hypoxylon canker, phenylalanine ammonia-lyase, cinnamyl - alcohol dehydrogenase, caffeic acid - o-methyltransferase, disease resistance.

Reduced Lignin Content and Altered Lignin Composition in Transgenic Tobacco Down-Regulated in Expression of L-Phenylalanine Ammonia-Lyase or Cinnamate 4-Hydroxylase

We analyzed lignin content and composition in transgenic tobacco (Nicotiana tabacum) lines altered in the expression of the early phenylpropanoid biosynthetic enzymes L-phenylalanine ammonia-lyase and cinnamate 4-hydroxylase (C4H). The reduction of C4H activity by antisense expression or sense suppression resulted in reduced levels of Klason lignin, accompanied by a decreased syringyl/guaiacyl monomer ratio as determined by pyrolysis gas chromatography/mass spectrometry Similar reduction of lignin levels by down -regulation of L-phenylalanine ammonia-lyase, the enzyme preceding C4H in the central phenylpropanoid pathway, did not result in a decreased syringyl/guaiacyl ratio. Rather, analysis of lignin methoxyl content and pyrolysis suggested an increased syringyl/guaiacyl ratio. One possible explanation of these results is that monolignol biosynthesis from L-phenylalanine might occur by more than one route, even at the early stages of the core phenylpropanoid pathway, prior to the formation of specific monolignol precursors.

Correlation of acid detergent lignin and Klason lignin with digestibility of forage dry matter and neutral detergent fiber

The acid detergent lignin and Klason lignin methods were compared for their correlation with forage digestibility. Thirty-six forages, including C3 legumes and C3 and C4 grasses, were analyzed for sulfuric acid detergent lignin, Klason lignin, and in vitro digestibilities of dry matter (DM) and neutral detergent fiber (NDF). Twenty of these forages were also fed to lambs at restricted intake for measurement of DM and NDF digestibilities. Lignin concentrations determined by the two lignin methods were positively correlated, and the Klason lignin value was always greater than the acid detergent lignin concentration. The largest differences were observed for grass forages. Digestibilities of forage DM and NDF were negatively correlated with both lignin methods for the in vitro system and the lamb digestibility trials. The degree of correlation for the two lignin methods with digestibility was generally similar across all forages and within forage classes. Slopes of linear regressions of digestibility on lignin concentration did not differ between legumes and grasses. Although the sulfuric acid detergent lignin and Klason lignin procedures gave very different estimates of forage lignin concentration, they were similarly correlated with digestibility and should yield predictions of forage digestibility that have similar accuracy.

Characteristics of plant cell walls affecting intake and digestibility of forages by ruminants

Even under the intensive concentrate feeding systems of ruminant animal production in the United States, forages continue to represent the single most important feed resource. Cell-wall concentration and digestibility limit the intake potential and energy availability of forage crops in beef and dairy production. Identification of cell-wall characteristics that should be targets of genetic modification is required if plant breeders and molecular biologists are to successfully improve forages for livestock feeding. As the forage plant cell develops, phenolic acids and lignin are deposited in the maturing cell wall in specific structural conformations, and in a strict developmental sequence. Lignin is the key element that limits cell-wall digestibility, but cross-linkage of lignin and wall polysaccharides by ferulic acid bridges may be a prerequisite for lignin to exert its affect. Lignin composition and p-coumaric acid in the wall are less likely to affect digestibility. Voluntary intake of forages is a critical determinant of animal performance and cell-wall concentration is negatively related to intake of ruminants consuming high-forage diets. Cell walls affect intake by contributing to ruminal fill. A simple model of cell-wall digestion and passage in which ruminal fill is a function of rates of digestion and passage, as well as the indigestible fraction of the cell-wall indicates that cell-wall concentration and rate of passage are the most critical parameters determining ruminal fill. Plant factors that affect rate of passage include those that affect particle size reduction by chewing and those that affect particle buoyancy in the rumen. The latter is primarily affected by 1) the ability of the particulate matter to retain gases, which is probably related to plant anatomy and rate of digestion of the plant tissue, and 2) the rate at which the gas is produced, which is affected by the potentially digestible fraction of the particulate matter and the rate of digestion of this fraction. Increasing rate of digestion should increase rate of passage by diminishing the gas produced and increasing density over time. A reduction in the indigestible cell-wall fraction is beneficial because this will decrease fill and increase digestibility. Animal production and economic benefits from reduced cell-wall concentration and increased digestibility are significant. Because of the high cell-wall concentration and large digestible cell-wall fraction of grasses, reduction in cell-wall concentration would probably be of greater value than improving digestibility in these species. Legumes represent the opposite situation and may benefit more from improvements in the digestibility of their cell walls.

Growth, digestive capability, carcass, and meat characteristics of Bison bison, Bos taurus, and Bos x Bison

Three experiments involving 39 Bos taurus, 14 Bison bison, and 20 Bos x Bison fed diets differing in proportions of roughage and concentrate to evaluate growth, digestive capability, carcass, and meat characteristics are reported. Bos taurus consumed more (P < .05) feed per day and gained more (P < .05) rapidly than bison or Bos x Bison except during a period of extremely cold weather. Efficiency of gain was similar for all species types. There was no tendency for bison or Bos x Bison to gain more than Bos taurus on the higher-roughage diets. Bison and Bos x Bison had higher (P < .10 to .01) digestion coefficients for all components evaluated (i.e., DM, CP, GE, NDF,hemicellulose, and cellulose). Species x diet interactions were not significant, indicating that the higher digestion coefficients of bison were not specific to high-roughage diets. Bison and their hybrids had more (P < .05) lean meat and less (P < .01) fat trim in all wholesale cuts except the chuck and rib cuts. Fat thickness at the 12th rib of bison was higher (P < .01) than that of Bos taurus because most of the carcass fat of bison is located over the thoracic area. Bison and Bos x Bison had higher (P < .01) dressing percentages and a lower (P < .01) proportion of their carcass in the hindquarter than Bos taurus. Shear force and sensory tenderness scores indicated bison were more (P < .05) tender and had a flavor different (P < .01) from that of Bos taurus. Bison and Bos x Bison had more (P < .01) cholesterol in the longissimus muscle and less (P < .05) in the subcutaneous fat than Bos taurus. Bison had a lower (P < .01) percentage of white and higher percentage of intermediate muscle fibers than Bos taurus with essentially no difference in percentage of red fibers.

Effect of alkaline hydrogen peroxide treatment on cell wall composition and digestion kinetics of sugarcane residues and wheat straw

Our objective was to characterize changes in cell wall composition and digestibility of sugarcane bagasse, pith from bagasse, and wheat straw after treatment with alkaline hydrogen peroxide (AHP). The AHP treatment solution contained 1% H2O2 (wt/vol) maintained at pH 11.5 with NaOH. The H2O2 in solution amounted to 25% of the quantity of substrate treated. After treatment, residues were washed and dried. Detergent fiber composition, total fiber components (neutral sugars, uronic acids, Klason lignin, and noncore lignin phenolic acids), IVDMD, in vitro digestion kinetics of NDF, and monosaccharide digestibilities (24 and 120 h) were determined. Total fiber (TF) and NDF concentrations of all treatment residues were increased (P less than .05) over control substrates by AHP because of greater losses of cell solubles than of cell wall constituents. Hemicellulose:cellulose ratio in NDF of treatment residues was decreased (P less than .05) by AHP for all substrates, but the neutral sugar composition of TF did not agree with this preferential loss of hemicellulose components. Klason lignin, ADL, and esterified noncore lignin, especially ferulic acid, were reduced (P less than .05) by AHP, whereas etherified noncore lignin composition was unchanged. Treatment increased (P less than .05) IVDMD, extent of NDF digestion, and monosaccharide digestibilities of all crop residues. The rate of NDF digestion was increased (P less than .05) for the sugarcane residues but not for wheat straw. Alkaline hydrogen peroxide improved crop residue digestibility, probably as a result of the removal of core and noncore lignin fractions.

Effect of white rot basidiomycetes on chemical composition and in vitro digestibility of oat straw and alfalfa stems

Five white rot basidiomycetes were evaluated for their potential to improve ruminal degradation of oat straw and alfalfa stems. Phanerochaete chrysosporium (PC), Scytinostroma galactinum (SG), Phlebia tremellosa (PT), Phellinus pini (PP), and Pholiota mutabilis (PM) were incubated on oat straw and alfalfa stems for 30 d at 28 degrees C and 90% relative humidity. Detergent fiber and total fiber components (neutral sugars, uronic acids, Klason lignin [KL], and ester- and ether-linked non-core lignin phenolics), core lignin nitrobenzene oxidation products, and IVDMD were determined. Electron microscopy of KMnO4-stained and cellulase/colloidal gold-labeled sections was used to monitor fungal activity. Large losses of DM were noted for all fungal species on both substrates. Lignin (KL and ADL) was removed (P less than .05) from oat straw by PC and PT treatment, but no net loss of lignin was observed for fungal treatment of alfalfa stems. Cell-wall polysaccharides were removed from both substrates by fungal activity. Only PC increased (P less than .05) IVDMD of oat straw, and SG, PT, PP, and PC treatment decreased (P less than .05) IVDMD of alfalfa stems, presumably because the fungi removed the most readily fermentable polysaccharides. Transmission electron microscopy using KMnO4 staining showed a nonselective white rot attack. Cytochemical studies using colloidal gold-labeled exo- and endocellulases were used to map the location of cellulose in the cell wall before and after decay by the white rot fungi. All the white rot fungi tested had eroded and thinned cell walls. Residual cell walls were well-labeled; both endo- and exocellulose-colloidal gold identified the cellulosic wall material that remained.(ABSTRACT TRUNCATED AT 250 WORDS)

Degradation of cellulose and forage fiber fractions by ruminal cellulolytic bacteria alone and in coculture with phenolic monomer-degrading bacteria

We hypothesized that bacterial species capable of metabolizing phenolic monomers may act as catalysts for forage fiber breakdown by increasing microbial access to cell wall polysaccharides. Ruminal cellulolytic bacteria alone and in combination with phenolic-degrading bacteria were examined for differences in their ability to degrade fiber fractions of alfalfa or bromegrass. Electron micrographs of Fibrobacter succinogenes S85 cultured in combination with the ruminal phenolic-degrading organisms Eubacterium oxidoreducens G41 and Syntrophococcus sucromutans S195 indicated that bromegrass was degraded more extensively by the triculture than by the monoculture. The sequential detergent system was used to quantify the digestibility of fiber components from alfalfa and bromegrass. F. succinogenes incubated with the two phenolic-degrading organisms did not degrade more cell wall material than did F. succinogenes alone. However, with two other ruminal cellulolytic organisms, Clostridium longisporum B6405 and Ruminococcus albus B6403, greater (P less than .05, P less than .10, respectively) amounts of hemicellulose were degraded (72 h in vitro fermentation) from whole-plant alfalfa when E. oxidoreducens and S. sucromutants were combined with the cellulolytic species than when their monocultures were tested. Similar increases were not observed using a NDF preparation of alfalfa as the substrate. Based on these in vitro experiments, it does not seem that E. oxidoreducens and S. sucromutans play an important role in improving forage fiber degradation by cellulolytic ruminal bacteria.

Development and validation of a prediction equation estimating heat production by carbon dioxide entry rate technique

A series of experiments was conducted to validate the CO2 entry rate technique (CERT) for prediction of heat production (HP) of sheep. Finnsheep cross wethers were used. Carbon dioxide production was estimated by continuous infusion of NaH14CO3 intraperitoneally and collection of saliva. Times required for 14C to equilibrate with the body CO2-bicarbonate pool and excretion of 14C in feces and urine were determined in four wethers (45.5 +/- 1.7 kg) infused for 3 d. Retention of radioactivity was measured for wethers (29.0 +/- 1.9 kg) slaughtered 3 h and 3, 10 and 15 d postinfusion. Using an indirect respiration calorimeter, CO2 production estimates were compared to values derived by CERT for six wethers (45.0 +/- .4 kg) fed at low, medium and high levels of intake. Further data on feed intake level and CO2 production were obtained from 24 wethers in two weight groups (29.5 +/- 1.1 and 42.3 +/- 1.4 kg) fed at three levels of intake. From 12 to 20 h were required for equilibration of NaH14CO3 and the body CO2-bicarbonate pool. Radioactivity of the saliva samples declined rapidly after cessation of infusion. Fecal and urine excretion of 14C was minimal. No detectable 14C was found in tissue of animals slaughtered after CERT. Estimates of daily CO2 production did not differ between the calorimetry and CERT measurements (20.6 vs 20.3 liters/kg body weight .75). Although feed intake levels were different, HP and respiratory quotients (RQ) did not differ between the methods. In the second calorimetry experiment, feed intake level was correlated with estimated HP. Respiratory quotient values did not differ among intake levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of forage type on ruminal bacterial populations and subsequent in vitro fiber digestion

Adaptation of the rumen fibrolytic bacteria to legume, C3 grass, and C4 grass forages was examined in a 3 X 3 Latin square. Fistulated steers were fed alfalfa, smooth bromegrass, and switchgrass hays for 6 wk at 1.8% of body weight. Rumen samples were collected weekly after an overnight fast. Bacterial counts were conducted on rumen samples and all rumen samples were used in an in vitro fiber digestion study with three stages of maturity each for alfalfa, smooth bromegrass, and switchgrass as the substrates. Consumption of alfalfa hay resulted in the highest total viable counts of rumen bacteria but a lower proportion of fibrolytic counts than seen on the grass diets. Use of filter paper as the isolation substrate gave higher fibrolytic counts than seen with NDF of the forage fed as the isolation substrate. Fifty percent or more of the fibrolytic bacteria were Bacteriodes succinogenes, and the switchgrass diet resulted in higher proportions of this organism in the fibrolytic population than seen for alfalfa and smooth bromegrass hays. The rumen inoculum from animals fed alfalfa degraded the fiber fractions of all substrate forages best. Improved in vitro digestibility of a forage was not observed due to feeding the same forage to the donor animals. Volatile fatty acid concentrations and proportions in the in vitro fermentations were related more to forage substrate than diet source. The results indicate that adaptation of the rumen population to diet forage composition occurred, but in vitro digestibility was unrelated to fibrolytic bacterial numbers or proportions.

Effect of dietary fiber on young adult genetically lean, obese and contemporary pigs: body weight, carcass measurements, organ weights and digesta content

Twenty-one genetically lean, obese or contemporary barrows (6 mo old; seven of each genotype) were assigned to individual tether stalls and fed a control diet (low-fiber) or a diet containing 80% alfalfa meal (high-fiber) at 1.50% of initial body weight for 71 d (1.75% for d 1 to 4). Backfat thickness was recorded ultrasonically at 2-wk intervals, and body weight was recorded at the beginning and end of the 10-wk experiment. Pigs were slaughtered after a 24-h fast, and carcass weight, length and backfat thickness and cross-sectional area of the longissimus muscle were measured. Weights of cecum, heart, liver and kidney and of full and empty stomach and colon and empty small intestine were recorded. Volume and weight of colon and cecum contents were determined. Restriction of digestible energy reduced weight gain to zero or below in pigs fed alfalfa meal compared with 220 g daily in pigs fed the low-fiber diet. Restriction of energy reduced backfat in all three genotypes. Liver, kidney and empty segments of the gastrointestinal tract as a percentage of body weight were increased by high fiber. Obese pigs had smaller longissimus muscle area, more backfat and smaller liver, heart, empty stomach and colon than lean or contemporary pigs, but there were no diet X genotype interactions for any of these traits. Obese pigs consistently had smaller digesta volumes and dry matter weights than the other genotypes. The increased relative organ weights and the associated disproportionate contribution of these organs to body energy expenditure have important implications for effects on basal metabolic rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dietary fiber of young adult genetically lean, obese and contemporary pigs: rate of passage, digestibility and microbiological data

Twenty-one genetically lean, obese or contemporary slaughter weight castrated male pigs (6 mo old; seven of each genotype) were assigned to individual tether stalls and fed either a control diet (low fiber) or a diet containing 80% alfalfa meal (high fiber) at 1.50% of initial body weight for 71 d (1.75% for d 1 to 4). Apparent dry matter digestibility of the diets was estimated by determining acid insoluble ash in fecal samples. Fecal cellulolytic bacteria and total viable bacteria were enumerated at d 0, 14, 35, 49 and 70. Fecal inocula were used to determine 48-h in vitro digestibility of alfalfa meal fractions on the same days. Digesta rate of passage was determined by feeding a pulse dose of chromium-mordanted alfalfa fiber to the pigs fed the high-fiber diet. In vivo digestibility of both diets was less for the obese pigs than for the lean or contemporary genotypes. In vitro digestibility of alfalfa fiber fractions was not different between the genotypes fed either diet. When the high-fiber diet was fed, in vitro digestibility increased for all genotypes from d 0 to d 14, but not thereafter. The numbers of cellulolytic bacteria for all three genotypes were greater when pigs were fed the high-fiber diet (23.0 X 10(8), 51.6 X 10(8), 37.2 X 10(8) per gram fecal dry weight; obese, lean and contemporary, respectively) compared to the low-fiber diet (3.0 X 10(8), 3.2 X 10(8), 3.4 X 10(8), respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of lignin on digestibility of forage cell wall material

One-hundred-ninety-four grass samples, representing eight species, were used to determine the relationships of in vitro forage dry matter, cell wall, hemicellulose and cellulose digestibilities with lignin concentration. Linear regressions indicated that dry matter digestion was inhibited to a lesser degree (P less than .05) by lignin concentration than was cell wall digestion. Results for linear regressions of hemicellulose and cellulose digestibilities as functions of lignin concentration showed a greater (P less than .05) effect of lignin on cellulose digestion. Smooth bromegrass and switchgrass were collected at both Clay Center and Mead, NE; for all digestibility measures, the Clay Center samples gave stronger (P less than .05) negative correlations with lignin. A comparison of linear and curvilinear models indicated that, for all digestion measurements, the curvilinear model was a better (P less than .05) description of relationships with lignin concentration. For all digestibility measures, lignin's inhibiting effect declined at higher lignin concentrations. The curvilinear models did not show significant differences among the digestibility measures for effect of lignin. The demonstration that the forage digestibility response to lignin's inhibitory effect is curvilinear in nature suggests that the mechanism of lignin's inhibition is complex.