Assessing the dynamic changes in vitiligo: reliability and validity of the Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS).

BACKGROUND: The assessment of the individual evolution of vitiligo is important for therapeutic decision making in daily practice. A fast, simple and validated physician-reported score to assess clinical changes in depigmentation over time in separate parts (activity and improvement) is currently missing. OBJECTIVE: The main objective of the study was to develop and validate the Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS). METHODS: The Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS) were evaluated based on a photo set of 66 patients with two different time points. In the first (short) version, only the number of changing body regions was counted based on 15 predefined areas (VDAS15 and VDIS15 ), while in the second (extensive) version the degree of worsening or improvement from +4 to -4 for each body area was added for a more detailed assessment (VDAS60 and VDIS60 ). Content and construct validity were tested. In addition inter-, intrarater reliability and feasibility were evaluated by 7 (test) and 5 (retest) physicians. RESULTS: Evidence for content and construct validity was provided. Overall, VDAS15 , VDIS15 , VDAS60 and VDIS60 demonstrated good to excellent inter-rater reliability [intraclass correlation (ICC): VDAS: range = 0.797-0.900; VDIS: range = 0.726-0.798]. The intrarater reliability ICCs were 0.865 and 0.781 for the VDAS15 and VDIS15 , respectively. Similar results were obtained for the VDAS60 and VDIS60 (ICC = 0.913 and 0.800, respectively). Completion time was short (median: 122 s/patient (first round); 95 s/patient (second round)]. LIMITATIONS: Single tertiary centre mainly of skin phototype 2 to 3. CONCLUSION: The VDAS and VDIS appear to be valid, reliable and feasible instruments to score the evolution of vitiligo lesions. This accommodates the current urgent need for a simple, standardized and practical assessment of vitiligo activity and improvement over time.

Technical note: Effects of filter bags on neutral detergent fiber recovery and fiber digestion in vitro.

Filter bags facilitate the measurement of amylase-treated neutral detergent fiber (aNDF) and in vitro (IV) undigested aNDF (uNDF) by eliminating the transfer of residues from beakers into filtration crucibles. The objectives of this study were to (1) determine effects of filter bags on recovery of aNDF and (2) evaluate effects of filter bags on IV uNDF. For study 1, 6 samples each of grass hay (GR), alfalfa (AL), and corn silage (CS) were selected. Large standard deviations (SD) of ash-free aNDF (aNDFom) for samples in each forage type indicated compositional diversity (15.1, 7.45, and 12.9% of DM for GR, AL, and CS, respectively), and starch SD for CS was 16.4% of DM. Samples were weighed into Berzelius beakers or filter bags [25-µm pores (F57) or 6-µm pores (F58); Ankom Technology, Macedon, NY] for measurement of aNDF and aNDFom. All samples were extracted with neutral detergent, thermostable α-amylase, and sodium sulfite, and then soaked in boiling water and then acetone. Residues from beakers were filtered through a sea sand-covered GF/D filter (Whatman, Marlborough, MA) in Gooch crucibles (CR). Filter bags were extracted in a pressurized chamber at 100°C. The aNDF values did not differ between F57 and CR, but F58 was greater than CR for CS and AL. For GR, F58 was greater than CR for aNDFom. For study 2, diverse samples with large SD of aNDFom (20.7, 7.45, and 12.9% of DM for GR, AL, and CS, respectively) were weighed as loose powder into medium bottles (LS) or F57 bags, which were weighted to prevent floating. Blended ruminal fluid from 3 steers fed a 30% aNDFom diet was used as inoculum. Three samples of 1 forage type were randomly assigned to 1 of 6 IV runs using both treatments (LS and F57), and 3 bottles of each sample-treatment combination were removed after 12 h and 2 were removed after 120 h to measure uNDF. For LS, residues were extracted as in study 1 for CR. For F57, bags were rinsed in cold water and extracted as described in study 1. After 12 h, uNDF of F57 was greater than LS in CS, AL, and overall types. Ash-free uNDF (uNDFom) after 12 h of F57 was greater than LS in CS and overall types. After 120 h, F57 was greater than LS for uNDF of CS, but no differences were detected for uNDFom. The SD of uNDFom, but not uNDF, was higher after 12 and 120 h for F57 compared with LS. From 6 to 96 h, overall gas production of F57 was less than LS, and F57 was less than LS for CS from 3 to 96 h. Overall, LS gave greater maximum and faster rates of gas production than F57, as did AL and CS, but lag did not vary. Results indicate that filter bags affected aNDF and aNDFom measurement and inhibited fermentation for some materials.

Clinical visible signs of disease activity in vitiligo: a systematic review and meta-analysis.

Vitiligo is an unpredictable depigmenting disorder for which a static method to assess disease activity is lacking. Presence of certain skin manifestations may be indicative of disease activity. Here, we evaluated the current evidence for an association between clinical signs and reported disease activity in vitiligo. A systematic review and meta-analysis was performed based on a search in PubMed, Embase and Cochrane Library. Literature reporting skin manifestations and disease activity was analysed based on descriptive analyses and, if applicable, odd ratios. Forty-six observational studies were selected and analysed, including 28 case reports. Reported clinical signs in relation to active vitiligo were as follows: Koebner's phenomenon, confetti-like depigmentations, tri- and hypochromic lesions (including poorly defined borders), inflammatory borders/areas, itch and leukotrichia. Based on this search, strong evidence was found for Koebner's phenomenon. Poorly defined borders and confetti lesions are potential markers, although more data are needed to confirm this. Evidence for other skin manifestations was inconclusive, whereas case reports on inflammatory borders were indicative of active disease. Limitations included the lack of randomized controlled trials, large-scale prospective studies and heterogeneity due to inconsistent definitions. This systematic review urges the vitiligo community to come forward with consensus-based definitions as well as a reliable scoring system to assess these clinical signs and to design optimal trials to investigate their true predictive value.

Adult vaccination for pneumococcal disease: a comparison of the national guidelines in Europe.

Pneumococcal disease constitutes a major global health problem. Adults aged over 50 years and younger adults with specific chronic health conditions are at risk for invasive pneumococcal disease, associated with substantial morbidity and mortality. In Europe, two vaccine types are used in adults for pneumococcal immunization: pneumococcal polysaccharide vaccine (PPV23) and pneumococcal conjugate vaccine (PCV13). To provide an overview and to compare the national guidelines for pneumococcal immunization for adults in Europe. In November 2016, national guidelines on pneumococcal vaccination for adults of 31 European countries were obtained by Google search, the website of European Centre for Disease Prevention and Control, and contacting public health officials. In our analysis, we distinguished between age-based and risk-based guidelines. In October 2017, we used the same method to retrieve guideline updates. We observed great variability regarding age, risk groups, vaccine type, and use of boosters. In age-based guidelines, vaccination is mostly recommended in adults aged over 65 years using PPV23. Boosters are generally not recommended. An upper age limit for vaccination is reported in three countries. In the immunocompromised population, vaccination with both vaccines and administration of a booster is mostly recommended. In the population with chronic health conditions, there is more heterogeneity according vaccine type, sequence, and administration of boosters. Asplenia is the only comorbidity for which all countries recommend vaccination. The great variability in European pneumococcal vaccination guidelines warrants European unification of the guidelines for better control of pneumococcal disease.

Stage of lactation and corresponding diets affect in situ protein degradation by dairy cows.

The influence of stage of lactation and corresponding diets on rates of protein degradation (kd) is largely unstudied. Study objectives were to measure and compare in situ ruminal kd of crude protein (CP) and estimate rumen CP escape (rumen-undegradable protein; RUP) of selected feeds by cows at 3 stages of lactation fed corresponding diets, and to determine the incubation times needed in an enzymatic in vitro procedure, using 0.2 units of Streptomyces griseus protease per percent of true CP, that predicted in situ RUP. Residue CP was measured after in situ fermentation for 4, 8, 12, 24, 36, 48, and 72 h of 5 protein sources and 3 total mixed rations, which were fed to the in situ cows. Two nonlactating (dry) cows and 2 cows each at 190 (mid) and 90 (peak) days of lactation were used. Each pair of cows was offered free-choice diets that differed in composition to meet their corresponding nutrient requirements. Diets had decreasing proportions of forages and contained (dry matter basis) 11.9, 15.1 and 16.4% CP and 54.3, 40.3 and 35.3% neutral detergent fiber, for dry, mid, and peak TMR (TMR1, TMR2, and TMR3), respectively. Intakes were 10.3, 21.4, and 23.8kg of dry matter/d, respectively. Kinetic CP fractions (extractable, potentially degradable, undegradable, or slowly degradable) were unaffected by treatment. Lag time and kd varied among feeds. The kd was faster for all feeds (0.136/h) when incubated in dry-TMR1 cows compared with mid-TMR2 (0.097/h) or peak-TMR3 (0.098/h) cows, and no differences in lag time were detected. Calculated RUP, using estimated passage rates for each cow based on intake, differed between dry-TMR1 (0.382) and mid-TMR2 (0.559) or peak-TMR3 (0.626) cows, with a tendency for mid-TMR2 to be different from peak-TMR3. Using the average kd and lag time obtained from dry-TMR1 to calculate RUP for mid-TMR2 and peak-TMR3 cows using their passage rates reduced RUP values by 6.3 and 9.5 percentage units, respectively. Except for that of herring meal, in vitro residue CP at 6, 12, and 48h of enzymatic hydrolysis was correlated (r=0.90) with in situ RUP of peak-TMR3, mid-TMR2, and dry-TMR1, respectively. Although confounded within treatments, stage of lactation, diet, and intake appeared to affect CP degradation parameters and RUP. Using kd from nonlactating cows, or the RUP calculated from them, may bias diet evaluation or ration formulation for lactating cows. In addition, enzymatic in vitro predictions of RUP should be measured using incubation times that are appropriate for lactating cows.

Defective DROSHA processing contributes to downregulation of MiR-15/-16 in chronic lymphocytic leukemia.

The MIR-15A/-16-1 tumor suppressor microRNAs (miRNAs) are deleted in leukemic cells from more than 50% of patients with chronic lymphocytic leukemia (CLL). As these miRNAs are also less abundant in patients without genomic deletion, their downregulation in CLL is likely to be caused by additional mechanisms. We found the primary transcripts (pri-miRNAs) of MIR-15a/-16/-15b to be elevated and processing intermediates (precursor miRNAs) to be reduced in cells from CLL patients (22/38) compared with non-malignant B-cells (n=14), indicating a block of miRNA maturation at the DROSHA processing step. Using a luciferase reporter assay for pri-miR processing we validated the defect in primary CLL cells. The block of miRNA maturation is restricted to specific miRNAs and can be found in the cell line MEC-2, but not in MEC-1, even though both are derived from the same CLL patient. In these cells, the RNA-specific deaminase ADARB1 leads to reduced pri-miRNA processing, but full processing efficiency is recovered upon deletion of the RNA-binding domains or nuclear localization of ADARB1. Thus, we show that, apart from genomic deletion or transcriptional downregulation, aberrant processing of miRNA leads to specific reduction of miRNAs in leukemic cells. This represents a novel oncogenic mechanism in the pathogenesis of CLL.

A query for effective mean particle size in dry and high-moisture corns.

The objective of this study was to investigate whether prediction of fermentation potential (FP) of dry and high-moisture (HM) corns could be improved by using a concept of effective (e) mean particle size (MPS). A set of FP standards was created by processing a single lot of Reid Yellow Dent (RYD) corn to achieve MPS of 3,778, 2,786, 2,282, 1,808, 1,410, 806, 586, 378, 308, 226, and 105 µm. In vitro gas production of RYD standards was measured, and peak absolute rate (PAR) of gas production (mL/0.2 g of DM/h) was used to establish a standard relationship between PAR and MPS. To identify factors other than MPS affecting FP, the MPS and nutrient composition of 36 diverse samples of dry (n=18) and HM (n=18) corns were determined. Composition included dry matter (DM), crude protein, soluble crude protein, neutral detergent fiber, starch, NH3-N, prolamin protein, and fat. In vitro gas production of undried, unground dry and HM corns was measured, and PAR, time of peak absolute rate (h), maximum cumulative gas production (mL/0.2 g of DM), gas production fractional rate (h⁻¹), and lag (h) were determined. Nonlinear relationships between MPS, defined as the dependent variable, and PAR, as an independent variable, were used to identify FP deviations unexplained by MPS. When no variation in nutritional composition was present (RYD standards), the relationship between PAR and MPS was described by an exponential decay model [RYD_MPS=9,006 × e((-0.452 × PAR)); R²=0.96]. For diverse dry and HM corn populations, the variation in MPS explained by PAR was diminished (R²=0.50). To investigate factors that diminish the relationship between MPS and PAR in diverse corns, relative residual (rr) MPS was determined [rrMPS = (MPS - RYD_MPS)/MPS], where RYD_MPS was predicted from the PAR of diverse dry and HM corn. The rrMPS was most highly related to prolamin protein [rrMPS(dry)=0.58-0.15 × (prolamin protein, % of DM); R²=0.43] and NH3-N [rrMPS(HM)=0.21+0.08 × (NH3-N, % of total N); R²=0.46] for dry and HM corns, respectively. An eMPS was calculated as eMPS = MPS - MPS × rrMPS, where rrMPS was predicted from prolamin protein or NH3-N concentration in dry and HM corn, respectively. The natural logarithm of eMPS accounted for 84% of the variability in PAR and 53% of the variability in the fractional rate of gas production. Calculating eMPS by adjusting the MPS of dry corn for prolamin and HM corn for NH3-N concentration improved the assessment of industry corn FP.

A ring test of in vitro neutral detergent fiber digestibility: analytical variability and sample ranking.

In vitro neutral detergent fiber (NDF) digestibility (NDFD) is an empirical measurement of fiber fermentability by rumen microbes. Variation is inherent in all assays and may be increased as multiple steps or differing procedures are used to assess an empirical measure. The main objective of this study was to evaluate variability within and among laboratories of 30-h NDFD values analyzed in repeated runs. Subsamples of alfalfa (n=4), corn forage (n=5), and grass (n=5) ground to pass a 6-mm screen passed a test for homogeneity. The 14 samples were sent to 10 laboratories on 3 occasions over 12 mo. Laboratories ground the samples and ran 1 to 3 replicates of each sample within fermentation run and analyzed 2 or 3 sets of samples. Laboratories used 1 of 2 NDFD procedures: 8 labs used procedures related to the 1970 Goering and Van Soest (GVS) procedure using fermentation vessels or filter bags, and 2 used a procedure with preincubated inoculum (PInc). Means and standard deviations (SD) of sample replicates within run within laboratory (lab) were evaluated with a statistical model that included lab, run within lab, sample, and lab × sample interaction as factors. All factors affected mean values for 30-h NDFD. The lab × sample effect suggests against a simple lab bias in mean values. The SD ranged from 0.49 to 3.37% NDFD and were influenced by lab and run within lab. The GVS procedure gave greater NDFD values than PInc, with an average difference across all samples of 17% NDFD. Because of the differences between GVS and PInc, we recommend using results in contexts appropriate to each procedure. The 95% probability limits for within-lab repeatability and among-lab reproducibility for GVS mean values were 10.2 and 13.4%, respectively. These percentages describe the span of the range around the mean into which 95% of analytical results for a sample fall for values generated within a lab and among labs. This degree of precision was supported in that the average maximum difference between samples that were not declared different by means separation was 4.4% NDFD. Although the values did not have great precision, GVS labs were able to reliably rank sample data in order of 30-h NDFD (Spearman correlation coefficient = 0.93) with 80% of the rankings correct or off by only 1 ranking. A relative ranking system for NDFD could reduce the effect of within- and among-lab variation in numeric values. Such a system could give a more accurate portrayal of the comparative values of samples than current numeric values imply.

Tissue perfusion in pathologies of the pancreas: assessment using 128-slice computed tomography.

PURPOSE: Perfusion CT can provide information regarding blood perfusion and permeability in (tumor) tissues in a non-invasive manner. In this study, values of CT perfusion parameters in several pancreas pathologies were determined and compared to a control population. MATERIALS AND METHODS: Dynamic 128-slice perfusion CT was performed in patients admitted to the radiology department between June 2010 and March 2011. Included pathologies were pancreatic adenocarcinoma, acute and chronic pancreatitis, neuroendocrine tumors, and (pseudo)cystic lesions. Parametric mappings of blood flow, blood volume, and permeability surface area product were generated. RESULTS: Blood flow and blood volume were significantly lower in acute and chronic pancreatitis compared to the control group. In the center of adenocarcinoma tumors, low blood flow and blood volume was observed, gradually increasing toward the tumor rim; perfusion values in pancreatic parenchyma adjacent to the tumor were not significantly different from the control population. In neuroendocrine tumors, significantly increased perfusion values were observed. CONCLUSION: Compared to the control population, significant decreases in perfusion values were observed in all pancreatic pathologies under study, except in neuroendocrine tumors. Perfusion CT values can be used as an additional parameter to differentiate pancreatic pathologies.

Work reintegration and cardiovascular disease: medical and rehabilitation influences.

INTRODUCTION: Research into work reintegration following cardiovascular disease onset is limited in its clinical and individual focus. There is no research examining worker experience in context during the return to work process. METHODS: Qualitative case study method informed by applied ethnography. Worker experience was assessed through longitudinal in-depth interviews with 12 workers returning to work following disabling cardiac illness. Workplace context (Canadian auto manufacturing plant) was assessed through site visits and meetings with stakeholders including occupational health personnel. Data was analyzed using constant comparison and progressive coding. RESULTS: Twelve men (43-63 years) participated in the study. Results revealed that unyielding production demands and performance monitoring pushed worker capacities and caused "insidious stress". Medical reassurance was important in the workers' decisions to return to work and stay on the job but medical restrictions were viewed as having limited relevance owing to limited understanding of work demands. Medical sanction was important for transient absence from the workplace as well as permanent disability. Cardiac rehabilitation programs were beneficial for lifestyle modification and building exercise capacity, but had limited benefit on work reintegration. Occupational health provided monitoring and support during work reintegration. CONCLUSIONS: Medical reassurance can be an important influence on worker representations of disease threat. Medical advice as it pertained to work activities was less valued as it lacked considerations of work conditions. Cardiac rehabilitation lacked intensity and relevance to work demands. Occupational health was reassuring for workers and played an important role in developing return to work plans.

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.

Variability in feed and total mixed ration neutral detergent fiber and crude protein analyses among commercial laboratories.

The objective of this study was to assess the variability in amylase-treated neutral detergent fiber (aNDF) and crude protein (CP) analyses of feed and total mixed ration (TMR) samples among feed analysis laboratories. Two TMR were prepared that varied in the dry matter proportion of forage and concentrates: 45% forage (LF-TMR) versus 60% forage (HF-TMR). Replicated TMR and individual feed samples were dried, ground through a 4-mm screen, and sent to 10 commercial and 4 research or development laboratories for aNDF and CP analyses. Laboratories were asked to complete a detailed questionnaire regarding the aNDF procedure used. Variability in aNDF and CP analyses was assessed using univariate statistics and mixed modeling procedures. Significant variability in the aNDF analysis of individual feeds was found among the participating laboratories. The variability was particularly large for low-aNDF feeds such as distillers and barley grains. The variability among laboratories in the aNDF analysis of low-fiber TMR was greater than of high-fiber TMR, with the most likely reason being their greater proportions of grains and protein concentrates and the effect of variation in the aNDF protocols, particularly α-amylase use, on the analysis of these types of feeds. Variability due to the technique used for aNDF analysis was not statistically significant when outlier labs using the filter bag technique were removed; however, laboratories using the filter bag technique tended to produce more variable results than did laboratories using variation of the crucible technique (SE=2.542 vs. 0.930, respectively). Calculated aNDF values for TMR, based on proportions and aNDF analysis of individual feeds, were slightly greater than analyzed aNDF values for TMR. Results from this ringtest emphasize the need for feed analysis laboratories to follow the official aNDF method exactly. Variation within and among laboratories can be reduced by replicating analysis and including reference materials in each analytical run. Results of CP analysis were more consistent among laboratories, and variability in CP analysis of individual feeds or TMR was marginally acceptable.

[Pulmonary hypertension due to left heart disease: recommendations of the Cologne Consensus Conference 2010]. / Pulmonale Hypertonie bei Linksherzerkrankungen: Empfehlungen der Kölner Konsensus-Konferenz 2010.

The 2009 European Guidelines on Diagnosis and Treatment of Pulmonary Hypertension have been adopted for Germany. While the guidelines contain detailed recommendations regarding pulmonary arterial hypertension (PAH), they contain only a relatively short paragraph on other, much more frequent forms of PH such as PH due to left heart disease. Despite the lack of data, targeted PAH treatments are increasingly being used for PH associated with left heart disease. This development is of concern. On the other hand, PH is a frequent problem that is highly relevant for morbidity and mortality in patients with left heart disease, so that it may be speculated whether selected patients may benefit from targeted PH therapy. It that sense, the practical implementation of the European Guidelines in Germany requires the consideration of several specific issues and already existing novel data. This requires a detailed commentary to the guidelines, and in some aspects an update already appears necessary. In June 2010, a Consensus Conference organized by the PH working groups of the German Society of Cardiology (DGK), the German Society of Respiratory Medicine (DGP) and the German Society of Pediatric Cardiology (DGPK) was held in Cologne, Germany. This conference aimed to solve practical and controversial issues surrounding the implementation of the European Guidelines in Germany. To this end, a number of working groups was initiated, one of which was specifically dedicated to PH due to left heart disease. This commentary summarizes the results and recommendations of this working group.

pH dynamics and bacterial community composition in the rumen of lactating dairy cows.

The influence of pH dynamics on ruminal bacterial community composition was studied in 8 ruminally cannulated Holstein cows fitted with indwelling electrodes that recorded pH at 10-min intervals over a 54-h period. Cows were fed a silage-based total mixed ration supplemented with monensin. Ruminal samples were collected each day just before feeding and at 3 and 6h after feeding. Solid and liquid phases were separated at collection, and extracted DNA was subjected to PCR amplification followed by automated ribosomal intergenic spacer analysis (ARISA). Although cows displayed widely different pH profiles (mean pH=6.11 to 6.51, diurnal pH range=0.45 to 1.39), correspondence analysis of the ARISA profiles revealed that 6 of the 8 cows showed very similar bacterial community compositions. The 2 cows having substantially different community compositions had intermediate mean pH values (6.30 and 6.33) and intermediate diurnal pH ranges (averaging 0.89 and 0.81 pH units). Fortuitously, these 2 cows alone also displayed milk fat depression, along with markedly higher ruminal populations of 1 bacterial operational taxonomic unit (OTU) and reduced populations of another ARISA amplicon. Cloning and sequencing of the elevated OTU revealed phylogenetic similarity to Megasphaera elsdenii, a species reportedly associated with milk fat depression. The higher populations of both M. elsdenii and OTU246 in these 2 cows were confirmed using quantitative real-time PCR (qPCR) with species-specific primers, and the fraction of total bacterial rDNA copies contributed by these 2 taxa were very highly correlated within individual cows. By contrast, the fraction of total bacterial rDNA copies contributed by Streptococcus bovis and genus Ruminococcus, 2 taxa expected to respond to ruminal pH, did not differ among cows (mean= <0.01 and 10.6%, respectively, of rRNA gene copies, determined by qPCR). The data indicate that cows with widely differing pH profiles can have similar ruminal bacterial community compositions, and that milk fat depression can occur at intermediate ruminal pH. The results support recent reports that milk fat depression is associated with shifts in bacterial community composition in rumine and is specifically related to the relative abundance of Megasphaera elsdenii.

Shifts in bacterial community composition in the rumen of lactating dairy cows under milk fat-depressing conditions.

Eighteen ruminally cannulated dairy cattle were fed a series of diets (in 28-d periods) designed to elicit different degrees of milk fat depression (MFD) for the purpose of relating MFD to ruminal bacterial populations. Cows were fed a TMR containing 25% starch (DM basis) supplied as corn silage, a slowly fermented starch (SFS treatment, period 1), then switched to a TMR containing 27% starch, much of it supplied as ground high-moisture corn, a rapidly fermented starch (RFS treatment, period 2). In period 3, the RFS diet was amended with 13.6 mg of monensin/kg of DM (RFS/Mon treatment), and in period 4, the cows were returned to the RFS diet without monensin (RFS/Post treatment). Effect of both starch source and monensin on milk fat percentage varied by cow, and cluster analysis identified 4 pairs of cows having distinct milk fat patterns. Archived ruminal liquors and solids from the 4 pairs were processed to isolate bacterial DNA, which was subjected to automated ribosomal intergenic spacer analysis followed by correspondence analysis to visualize bacterial community composition (BCC). One pair of cows (S-responsive) showed MFD on RFS feeding, but displayed no additional MFD upon monensin feeding and a fat rebound upon monensin withdrawal. The second pair of cows (M-responsive) showed no MFD upon switch from the SFS diet to the RFS diet, but displayed strong MFD upon monensin feeding and no recovery after monensin withdrawal. Both groups displayed major shifts in BCC upon dietary shifts, including dietary shifts that both did and did not change milk fat production. The third pair of cows (SM-responsive) displayed reduction of milk fat on both RFS and RFS/Mon diets, and fat returned to the levels on the RFS diet upon monensin withdrawal; these cows showed a more gradual shift in BCC in response to both starch source and monensin. The fourth pair of cows (nonresponsive) did not display changes in milk fat percentage with dietary treatment and showed only minor shifts in BCC with dietary treatment. Regardless of milk fat response, BCC did not reassemble its original state upon monensin withdrawal, though the difference was strongest in M-responsive cows. One amplicon length (representing a single bacterial species) was elevated in most, but not all, MFD-susceptible (S-, M-, or SM-responsive) cows relative to milk fat-nonresponsive cows, whereas 2 amplicon lengths displayed reduced abundance under MFD conditions. Overall, this study demonstrates an association between MFD and wholesale shifts of microbial communities in the rumen.