Reducing Patient Care Delays in Radiation Oncology via Optimization of Insurance Pre-Authorization

PURPOSE/OBJECTIVE(S)

Difficulties and delays in insurance pre-authorization (pre-auth) can negatively impact patient care, resulting in postponing, modifying, or even cancelling radiation therapy for patients. Unfortunately, pre-auth delays are not uncommon. The purpose of our project was to perform a root cause analysis of reasons for pre-auth delays, and implement solutions to optimize our workflow to better serve our patients. Our primary objectives were to decrease the mean time for clinical treatment plan (CTP) completion, and for number of cases delayed/denied, by 50% each.

MATERIALS/METHODS

We performed a root cause analysis of reasons for pre-auth delays and used the PDSA & A3 quality improvement methods. We sampled ∼2 cases per disease site (total 19 cases from July - Aug 2022) to determine the "current state," pre-interventions. Countermeasures included: 1) customizing our CTP templates for each disease site to contain the specific clinical information required by each insurer, 2) formalizing earlier completion of CTPs through task automation at time of scheduling CT simulation in our Care Path, and 3) continuously refining our countermeasures based on monthly status updates and department meetings. We tracked various physician, authorization, and outcome-metrics between October 2022 and January 2023, including mean time for CTP completion, % usage of our Care Path, % usage of revised CTP templates, mean time until pre-auth initiated & completed, % of cases requiring peer-to-peer phone calls, and % of cases denied/delayed.

RESULTS

There were 417 patients from a variety of disease sites who had a CT simulation at our institution between October 1, 2022, and January 31, 2023. Mean time for CTP completion (from the time of CT simulation request) improved from 16 days at baseline to 7 days by the end of the project. In the beginning, only 5% of CTPs were completed within 2 days of scheduling the CT simulation, and this improved to 42-56% during the project period. Percent usage of the Care Path improved dramatically from 16% to 91%, as did % usage of our revised CTP templates, from 0% to 96%. Despite initial lag in pre-authorization team workflow changes, the % of pre-authorizations initiated by day 3 from CT request improved from 32% at baseline to 48% by month 4. Mean time to complete insurance pre-authorizations improved from 16 days at baseline to 10 days. The percent of cases requiring peer to peer or were denied was reduced significantly from 32% at baseline to 4-11%.

CONCLUSION

Improvingtimeliness and details of CTP documentation by using our Care Path and revising CTP templates improved efficiency of insurance pre-auth completion, and reduced the number of cases delayed/denied.

Methane emission, nutrient digestibility, and rumen microbiota in Holstein heifers fed 14 different grass or clover silages as the sole feed

This experiment investigated the variation in enteric methane production and associated gas exchange parameters, nutrient digestibility, rumen fermentation, and rumen microbiome when a range of silages based on different forage types (grass or clover), and different species within the 2 types, were fed as the sole feed to heifers. Three grass species (perennial ryegrass, festulolium, and tall fescue) and 2 clover species (red clover and white clover) were included. Perennial ryegrass was harvested at 2 maturity stages in the primary growth, white clover was harvested once in the primary growth, and 4 cuts of festulolium and tall fescue and 3 cuts of red clover were harvested during the growing season, giving 14 different silage batches in total. Sixteen Holstein heifers 16 to 21 mo old and 2 to 5 mo in pregnancy were fed the silages ad libitum as the sole feed in an incomplete crossover design. Each silage was fed to 4 heifers, except for the 2 perennial ryegrass silages, which were fed to 8 heifers; in total 64 observations. The CH₄ production was measured for 3 d in respiration chambers. Heifers fed clover silages had higher dry matter intake (DMI) compared with heifers fed grass silages, and heifers fed tall fescue silages had the numerically the lowest DMI. Compared with grass silages, feeding clover silages led to higher crude protein digestibility but lower neutral detergent fiber (NDF) digestibility. Rumen pH was higher in heifers fed clover silages compared with those fed grass silages. Based on composition analysis, the rumen microbiota of the heifers clustered clearly according to forage type and species. More specifically, 7 of the 34 dominating rumen bacterial genus-level groups showed higher relative abundances for the clover silages, whereas 7 genus-level groups showed higher abundances for the grass silages. Methane yield was higher for heifers fed grass silages than for those fed clover silages when methane production was related to dry matter and digestible organic matter intake, whereas the opposite was seen when related to NDF digestion. The gross energy lost as methane (CH₄ conversion factor, %) reduced from 7.5% to 6.7%, equivalent to an 11% reduction. The present study gives the outlines for choosing the optimal forage type and forage species with respect to nutrient digestibility and enteric methane emission in ruminants.

Invited review: Corrected milk: Reconsideration of common equations and milk energy estimates

Corrected milk equations were developed in attempts to bring milk weights to a standardized basis for comparison by expressing the weight and composition of milk as corrected to the energy content of milk of a specific composition. Expressed as milk weights familiar on farm and in commerce, this approach integrates energy contributions of the dissimilar components to make the mass units more comparable. Such values are applied in evaluating feed efficiency, lactation performance, and global milk production, as functional units for lifecycle assessments, and in translation of research results. Corrected milk equations are derived from equations relating milk gross energy to milk composition. First, a milk energy equation is used to calculate the energy value of the milk composition to correct to (e.g., 0.695 Mcal/kg for milk with 3.5% fat, 3.05% true protein, and 4.85% lactose). That energy value is divided into the energy equation to give the corrected milk equation. Confusion has arisen, as different equations purport to correct to the same milk composition; their differences are based on uses of different energy equations or divisors. Accuracy of corrected milk equations depends on the accuracy of the energy equations used to create them. Energy equations have evolved over time as different milk component analyses have become more available. Inclusion of multiple milk components more accurately predicts milk energy content than does fat content alone. Omission of components from an equation requires the assumption that their content in milk is constant or highly correlated with an included component. Neither of these assumptions is true. Milk energy equations evaluated on a small data set of measured milk values have demonstrated that equations that incorporate protein, fat, and lactose contents multiplied by the gross energy of each component more closely predict milk energy than equations containing fewer components or regression-derived equations. This provides a tentative recommendation for using energy equations that include the 3 main milk components and their gross energy multipliers for predicting milk energy and deriving corrected milk equations. Accuracy of energy equations is affected by the accuracy of gross energy values of individual components and variability of milk composition. Lactose has consistent reported gross energy values. In contrast, gross energy of milk fat and protein vary as their compositional profiles change. Future refinements could assess accuracy of milk fat and protein gross energy and whether that appreciably improves milk energy predictions. Fat gross energy has potential to be calculated using the milk fatty acid profile, although the influence on gross energy may be small. For research, direct reporting of milk energy values, rather than corrected milk, provides the most explicit, least manipulated form of the data. However, provision of corrected milk values in addition to information on components can serve to translate the energy information to a form familiar to and widely used in the field. When reporting corrected milk data, the corrected milk equation, citation for the energy equation used, and composition and energy contents of the corrected milk must be described to make clear what the values represent.

Rumen volatile fatty acid molar proportions, rumen epithelial gene expression, and blood metabolite concentration responses to ruminally degradable starch and fiber supplies

The objective of this work was to characterize rumen volatile fatty acid (VFA) concentrations, rumen epithelial gene expression, and blood metabolite responses to diets with different starch and fiber sources. Six ruminally cannulated yearling Holstein heifers (body weight = 330 ± 11.3 kg) were arranged in a partially replicated Latin square experiment with 4 treatments consisting of different starch [barley (BAR) or corn (CRN)] and fiber [timothy hay (TH) or beet pulp (BP)] sources. Treatments were arranged as a 2 × 2 factorial. Beet pulp and TH were used to create relative changes in apparent ruminal fiber disappearance, whereas CRN and BAR were used to create relative changes in apparent ruminal starch disappearance. Each period consisted of 3 d of diet adaptation and 15 d of dietary treatment. In situ disappearance of fiber and starch were estimated from bags incubated in the rumen from d 10 to 14. From d 15 to 17, rumen fluid was collected every hour from 0500 to 2300 h. Rumen fluid samples were pooled by animal/period and analyzed for pH and VFA concentrations. On d 18, 60 to 80 papillae were biopsied from the epithelium and preserved for gene expression analysis. On d 18, one blood sample per heifer was collected from the coccygeal vessel. In situ ruminal starch disappearance rate (7.30 to 8.72%/h for BAR vs. 7.61 to 10.5%/h for CRN) and the extent of fiber disappearance (22.2 to 33.4% of DM for TH vs. 34.4 to 38.7% of DM for BP) were affected by starch and fiber source, respectively. Analysis of VFA molar proportions showed a shift from propionate to acetate, and valerate to isovalerate on TH diets compared with BP. Corn diets favored propionate over butyrate in comparison to BAR diets. Corn diets also had higher molar proportions of valerate. Expression of 1 gene (SLC9A3) were increased in BP diets and 2 genes (BDH1 and SLC16A4) tended to be increased in TH diets. Plasma acetate demonstrated a tendency for a starch by fiber interaction with BAR-BP diets having the highest plasma acetate, but other metabolites measured were not significant. These results suggest that TH has the greatest effect on shifts in VFA molar proportions and epithelial transporters, but does not demonstrate shifts in blood metabolite concentrations.

Contributions of dairy products to environmental impacts and nutritional supplies from United States agriculture

Questions regarding the balance between the contribution to human nutrition and the environmental impact of livestock food products rarely evaluate specific species or how to accomplish the recommended depopulation. The objective of this study was to assess current contributions of the US dairy industry to the supply of nutrients and environmental impact, characterize potential impacts of alternative land use for land previously used for crops for dairy cattle, and evaluate the impacts of these approaches on US dairy herd depopulation. We modeled 3 scenarios to reflect different sets of assumptions for how and why to remove dairy cattle from the US food production system coupled with 4 land-use strategies for the potential newly available land previously cropped for dairy feed. Scenarios also differed in assumptions of how to repurpose land previously used to grow grain for dairy cows. The current system provides sufficient fluid milk to meet the annual energy, protein, and calcium requirements of 71.2, 169, and 254 million people, respectively. Vitamins supplied by dairy products also make up a high proportion of total domestic supplies from foods, with dairy providing 39% of the vitamin A, 54% of the vitamin D, 47% of the riboflavin, 57% of the vitamin B₁₂, and 29% of the choline available for human consumption in the United States. Retiring (maintaining animals without milk harvesting) dairy cattle under their current management resulted in no change in absolute greenhouse gas emissions (GHGE) relative to the current production system. Both depopulation and retirement to pasture resulted in modest reductions (6.8-12.0%) in GHGE relative to the current agricultural system. Most dairy cow removal scenarios reduced availability of essential micronutrients such as α-linolenic acid, Ca, and vitamins A, D, B₁₂, and choline. Those removal scenarios that did not reduce micronutrient availability also did not improve GHGE relative to the current production system. These results suggest that removal of dairy cattle to reduce GHGE without reducing the supply of the most limiting nutrients to the population would be difficult.

Development of feed composition tables using a statistical screening procedure

Millions of feed composition records generated annually by testing laboratories are valuable assets that can be used to benefit the animal nutrition community. However, it is challenging to manage, handle, and process feed composition data that originate from multiple sources, lack standardized feed names, and contain outliers. Efficient methods that consolidate and screen such data are needed to develop feed composition databases with accurate means and standard deviations (SD). Considering the interest of the animal science community in data management and the importance of feed composition tables for the animal industry, the objective was to develop a set of procedures to construct accurate feed composition tables from large data sets. A published statistical procedure, designed to screen feed composition data, was employed, modified, and programmed to operate using Python and SAS. The 2.76 million data received from 4 commercial feed testing laboratories were used to develop procedures and to construct tables summarizing feed composition. Briefly, feed names and nutrients across laboratories were standardized, and erroneous and duplicated records were removed. Histogram, univariate, and principal component analyses were used to identify and remove outliers having key nutrients outside of the mean ± 3.5 SD. Clustering procedures identified subgroups of feeds within a large data set. Aside from the clustering step that was programmed in Python to automatically execute in SAS, all steps were programmed and automatically conducted using Python followed by a manual evaluation of the resulting mean Pearson correlation matrices of clusters. The input data set contained 42, 94, 162, and 270 feeds from 4 laboratories and comprised 25 to 30 nutrients. The final database included 174 feeds and 1.48 million records. The developed procedures effectively classified by-products (e.g., distillers grains and solubles as low or high fat), forages (e.g., legume or grass-legume mixture by maturity), and oilseeds versus meal (e.g., soybeans as whole raw seeds vs. soybean meal expellers or solvent extracted) into distinct sub-populations. Results from these analyses suggest that the procedure can provide a robust tool to construct and update large feed data sets. This approach can also be used by commercial laboratories, feed manufacturers, animal producers, and other professionals to process feed composition data sets and update feed libraries.

Short communication: Gelatinization and enzymatic hydrolysis characteristics relevant to digestion and analysis of glycogen granules isolated from ruminal protozoa

Glycogen is an α-glucan produced by rumen microbes from various feed carbohydrates. It may be digested ruminally or intestinally to provide nutrients. The physicochemical and enzymatic hydrolysis characteristics of microbial glycogen have not been described in detail, but do influence its conversion to absorbable nutrients in vivo, its nutritional comparability with plant starch sources, and its accurate analysis in vitro. The objectives of this study were to determine presence or absence of a gelatinization response and to describe enzymatic digestion characteristics of glycogen granules isolated from ruminal protozoa obtained from lactating dairy cows. Protozoal glycogen granules were determined to be 98.3% α-glucan. Granules displayed gelatinization, the breaking of hydrogen bonds between molecules or branches, at 65°C compared with purified wheat and corn starches, which initiated gelatinization at 50 and 65°C, respectively. Digestion of ungelatinized samples with amyloglucosidase for 2 h at 39°C showed approximately 3-fold greater hydrolysis to glucose for protozoal glycogen (25.2% of dry matter; DM) than for wheat (9.9% of DM) or corn (8.2% of DM) starches. Based on enzymatic digestion results, protozoal glycogen may be more readily digested than intact corn or wheat starches and should be gelatinized or the hydrogen bonds otherwise disrupted to allow more complete recovery in enzymatic analysis.

Postpartum supplementation of fermented ammoniated condensed whey improved feed efficiency and plasma metabolite profile

Postpartum dietary supplementation of gluconeogenic precursors may improve the plasma metabolite profile of dairy cows, reducing metabolic disorders and improving lactation performance. The objective of this trial was to examine the effects of supplementation with fermented ammoniated condensed whey (FACW) postpartum on lactation performance and on profile of plasma metabolites and hormones in transition dairy cows. Individually fed multiparous Holstein cows were blocked by calving date and randomly assigned to control (2.9% dry matter of diet as soybean meal; n = 20) or FACW (2.9% dry matter of diet as liquid GlucoBoost, Fermented Nutrition, Luxemburg, WI; n = 19) dietary treatments. Treatments were offered from 1 to 45 d in milk (DIM). Cows were milked twice a day. Dry matter intake and milk yield were recorded daily and averaged weekly. Individual milk samples from 2 consecutive milkings were obtained once a week for component analysis. Rumen fluid was collected (n = 3 cows/treatment) at 4 time points per day at 7 and 21 DIM. Blood samples were collected within 1 h before feeding time for metabolite analysis and hyperketonemia diagnosis. Supplementation of FACW improved feed efficiency relative to control; this effect may be partially explained by a marginally significant reduction in dry matter intake from wk 3 to 7 for FACW-supplemented cows with no detected FACW-driven changes in milk yield, milk protein yield, and milk energy output compared with control. Also, there was no evidence for differences in intake of net energy for lactation, efficiency of energy use, energy balance, or body weight or body condition score change from calving to 45 DIM between treatments. Supplementation of FACW shifted rumen measures toward greater molar proportions of propionate and butyrate, and lesser molar proportions of acetate and valerate. Cows supplemented with FACW had greater plasma glucose concentrations in the period from 3 to 7 DIM and greater plasma insulin concentrations compared with control. Plasma nonesterified fatty acid and β-hydroxybutyrate concentrations were decreased in cows supplemented with FACW compared with control cows in the period from 3 to 7 DIM. These findings indicate that FACW may have improved the plasma metabolite profile immediately postpartum in dairy cows. Additionally, supplementation of FACW resulted in improved feed efficiency as accessed by measures of milk output relative to feed intake.

Dehalogenation of chloroalkanes by nickel(i) porphyrin derivatives, a computational study

We constructed theoretical models of the dehalogenation of chloromethane by a nickel(i) isobacteriochlorin anion and compared its reactivity with that of similar Ni^(I) complexes with other porphyrin-derived ligands: porphyrin, chlorin, bactreriochlorin, hexahydroporphyrin and octahydroporphyrin.

Divergent utilization patterns of grass fructan, inulin, and other nonfiber carbohydrates by ruminal microbes

Fructans are an important nonfiber carbohydrate in cool season grasses. Their fermentation by ruminal microbes is not well described, though such information is needed to understand their nutritional value to ruminants. Our objective was to compare kinetics and product formation of orchardgrass fructan (phlein; PHL) to other nonfiber carbohydrates when fermented in vitro with mixed or pure culture ruminal microbes. Studies were carried out as randomized complete block designs. All rates given are first-order rate constants. With mixed ruminal microbes, rate of substrate disappearance tended to be greater for glucose (GLC) than for PHL and chicory fructan (inulin; INU), which tended to differ from each other (0.74, 0.62, and 0.33 h(-1), respectively). Disappearance of GLC had almost no lag time (0.04 h), whereas the fructans had lags of 1.4h. The maximum microbial N accumulation, a proxy for cell growth, tended to be 20% greater for PHL and INU than for GLC. The N accumulation rate for GLC (1.31h(-1)) was greater than for PHL (0.75 h(-1)) and INU (0.26 h(-1)), which also differed. More microbial glycogen (+57%) was accumulated from GLC than from PHL, though accumulation rates did not differ (1.95 and 1.44 h(-1), respectively); little glycogen accumulated from INU. Rates of organic acid formation were 0.80, 0.28, and 0.80 h(-1) for GLC, INU, and PHL, respectively, with PHL tending to be greater than INU. Lactic acid production was more than 7-fold greater for GLC than for the fructans. The ratio of microbial cell carbon to organic acid carbon tended to be greater for PHL (0.90) and INU (0.86) than for GLC (0.69), indicating a greater yield of cell mass per amount of substrate fermented with fructans. Reduced microbial yield for GLC may relate to the greater glycogen production that requires ATP, and lactate production that yields less ATP; together, these processes could have reduced ATP available for cell growth. Acetate molar proportion was less for GLC than for fructans, and less for PHL than for INU. In studies with pure cultures, all microbes evaluated showed differences in specific growth rate constants (μ) for GLC, fructose, sucrose, maltose, and PHL. Selenomonas ruminantium and Streptococcus bovis showed the highest μ for PHL (0.55 and 0.67 h(-1), respectively), which were 50 to 60% of the μ achieved for GLC. The 10 other species tested had μ between 0.01 and 0.11h(-1) with PHL. Ruminal microbes use PHL differently than they do GLC or INU.

Aliphatic–aromatic stacking interactions in cyclohexane–benzene are stronger than aromatic–aromatic interaction in the benzene dimer

Stacking interactions between cyclohexane and benzene were studied in crystal structures from the Cambridge Structural Database and by ab initio calculations.

Total volatile fatty acid concentrations are unreliable estimators of treatment effects on ruminal fermentation in vivo

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.

Effect of variable water intake as mediated by dietary potassium carbonate supplementation on rumen dynamics in lactating dairy cows

Water is a critical nutrient for dairy cows, with intake varying with environment, production, and diet. However, little work has evaluated the effects of water intake on rumen parameters. Using dietary potassium carbonate (K2CO3) as a K supplement to increase water intake, the objective of this study was to evaluate the effect of K2CO3 supplementation on water intake and on rumen parameters of lactating dairy cows. Nine ruminally cannulated, late-lactation Holstein cows (207±12d in milk) were randomly assigned to 1 of 3 treatments in a replicated 3×3 Latin square design with 18-d periods. Dietary treatments (on a dry matter basis) were no added K2CO3 (baseline dietary K levels of 1.67% dietary K), 0.75% added dietary K, and 1.5% added dietary K. Cows were offered treatment diets for a 14-d adaption period followed by a 4-d collection period. Ruminal total, liquid, and dry matter digesta weights were determined by total rumen evacuations conducted 2h after feeding on d 4 of the collection period. Rumen fluid samples were collected to determine pH, volatile fatty acids, and NH3 concentrations, and Co-EDTA was used to determine fractional liquid passage rate. Milk samples were collected twice daily during the collection period. Milk, milk fat, and protein yields showed quadratic responses with greatest yields for the 0.75% added dietary K treatment. Dry matter intake showed a quadratic response with 21.8kg/d for the 0.75% added dietary K treatment and 20.4 and 20.5kg/d for control and the 1.5% added dietary K treatment, respectively. Water intake increased linearly with increasing K2CO3 supplementation (102.4, 118.4, and 129.3L/d) as did ruminal fractional liquid passage rate in the earlier hours after feeding (0.118, 0.135, and 0.141 per hour). Total and wet weights of rumen contents declined linearly and dry weight tended to decline linearly as dietary K2CO3 increased, suggesting that the increasing water intake and fractional liquid passage rate with increasing K2CO3 increased the overall ruminal turnover rate. Ruminal ammonia concentrations declined linearly and pH increased linearly as K supplementation increased. As a molar percentage of total volatile fatty acids, acetate increased linearly as dietary K increased, though propionate declined. Increasing dietary K2CO3 and total K in the diets of lactating dairy cows increased water consumption and modified ruminal measures in ways suggesting that both liquid and total ruminal turnover were increased as both water and K intake increased.

Basis sets for transition metals: Optimized outer p functions

Although the (n + 1)p orbital is unoccupied in transition-metal ground-state configurations which are all nd(x) (n + 1)s(y) , these (n + 1)p functions play a crucial role in the structure of transition metal complexes. As we show here, the usual solution, adding one or more diffuse functions, can be insufficient to create an orbital of the correct energy. The major problem appears to be due to the incorrect placement of the (n + 1)p orbital's node. Even splitting the most diffuse component of the np orbital and adding a second diffuse function does not completely solve this problem. Although one can usually solve this deficiency by further uncontracting of the np function, here we offer a set of properly optimized (n + 1)p functions that offer a more compact and satisfactory solution to the proper placements of the node. We show an example of the common deficiencies seen in typical basis sets, including standard basis sets in GAUSSIAN94, and show that the new optimized (n + 1)p function performs well compared to a fully uncontracted basis set. © 1996 by John Wiley & Sons, Inc.

Responses of late-lactation cows to forage substitutes in low-forage diets supplemented with by-products

In response to drought-induced forage shortages along with increased corn and soy prices, this study was conducted to evaluate lactation responses of dairy cows to lower-forage diets supplemented with forage substitutes. By-product feeds were used to completely replace corn grain and soybean feeds. Forty-eight late-lactation cows were assigned to 1 of 4 diets using a randomized complete block design with a 2-wk covariate period followed by a 4-wk experimental period. The covariate diet contained corn grain, soybean meal, and 61% forage. Experimental diets contained chopped wheat straw (WS)/sugar beet pulp at 0/12, 3/9, 6/6, or 9/3 percentages of diet dry matter (DM). Corn silage (20%), alfalfa silage (20%), pelleted corn gluten feed (25.5%), distillers grains (8%), whole cottonseed (5%), cane molasses/whey blend (7%), and vitamin and mineral mix with monensin (2.5%) comprised the rest of diet DM. The WS/sugar beet pulp diets averaged 16.5% crude protein, 35% neutral detergent fiber, and 11% starch (DM basis). Cows consuming the experimental diets maintained a 3.5% fat- and protein-corrected milk production (35.2 kg; standard deviation=5.6 kg) that was numerically similar to that measured in the covariate period (35.3 kg; standard deviation=5.0 kg). Intakes of DM and crude protein declined linearly as WS increased, whereas neutral detergent fiber intake increased linearly. Linear increases in time spent ruminating (from 409 to 502 min/d) and eating (from 156 to 223 min/d) were noted as WS inclusion increased. Yields of milk fat and 3.5% fat-and protein-corrected milk did not change as WS increased, but those of protein and lactose declined linearly. Phosphorous intakes were in excess of recommended levels and decreased linearly with increasing WS inclusion. Nutritional model predictions for multiparous cows were closest to actual performance for the National Research Council 2001 model when a metabolizable protein basis was used; primiparous cow performance was better predicted by energy-based predictions made with the National Research Council or Cornell Net Carbohydrate and Protein System models. Model predictions of performance showed a quadratic diet effect with increasing WS. Lactating dairy cows maintained production on low-forage diets that included forage substitutes, and in which by-product feeds fully replaced corn grain and soybean. However, longer-term studies are needed to evaluate animal performance and to improve model predictions of performance on these nontraditional diets.

Recent theoretical predictions of the active site for the observed forms in the catalytic cycle of Ni-Fe hydrogenase

Various states or forms of the active site in Ni-Fe hydrogenase, both catalytically active and inactive forms, have been identified and investigated experimentally. Until recently, the geometric structure of each form remained an open question. Several recent theoretical studies with density functional theory have attempted to redress this deficiency. In this commentary, the similarities and differences among the structures proposed by these studies will be addressed.

Isotrichid protozoa influence conversion of glucose to glycogen and other microbial products

The goal of this in vitro study was to determine the influence of isotrichid protozoa (IP) on the conversion of glucose (Glc) to glycogen (Glyc) and transformation of Glc into fermentation products. Treatments were ruminal inoculum mechanically processed (blended) to destroy IP (B+, verified microscopically) or not mechanically processed (B-). Accumulated microbial Glyc was measured at 3h of fermentation with (L+; protozoa+bacteria) or without (L- predominantly protozoa) lysis of bacterial cells in the fermentation solids with 0.2 N NaOH. Two 3-h in vitro fermentations were performed using Goering-Van Soest medium in batch culture vessels supplemented with 78.75 mg of Glc/vessel in a 26.5-mL liquid volume. Rumen inoculum from 2 cannulated cows was filtered through cheesecloth, combined, and maintained under CO(2) for all procedures. At 3h, 0.63 and 0.38 mg of Glc remained in B- and B+. Net microbial Glyc accumulation (and Glc in Glyc as % of added Glc) detected at 3h of fermentation were 3.32 (4.69%), -1.42 (-2.01%), 6.45 (9.10%), and 3.65 (5.15%) mg for B-L-, B+L-, B-L+ and B+L+, respectively. Treatments B+ and L+ gave lower Glyc values than B- and L-, respectively. Treatment B+L- demonstrated net utilization of α-glucan contributed by inoculum with no net Glyc production. With destruction of IP, total Glyc accumulation declined by 44%, but estimated bacterial Glyc increased. Microbial accumulation of N increased 17.7% and calculated CH(4) production decreased 24.7% in B+ compared with B-, but accumulation of C in microbes, production of organic acids or C in organic acids, calculated CO(2), and carbohydrates in cell-free medium did not differ between B+ and B-. Given the short 3-h timeframe, increased N accumulation in B+ was attributed to decreased Glyc sequestration by IP rather than decreased predation on bacteria. After correction for estimates of C from AA and peptides utilized by microbes, 15% of substrate Glc C could not be accounted for in measured products in B+ or B-. Approximately 30% of substrate Glc was consumed by energetic costs associated with Glc transport and Glyc synthesis. The substantial accumulation of Glyc and changes in microbial N and Glyc accumulation related to presence of IP suggest that these factors should be considered in predicting profiles and amounts of microbial products and yield of nutrients to the cow as related to utilization of glucose. Determination of applicability of these findings to other soluble carbohydrates could be useful.

Ruminant Nutrition Symposium: Productivity, digestion, and health responses to hindgut acidosis in ruminants

Microbial fermentation of carbohydrates in the hindgut of dairy cattle is responsible for 5 to 10% of total-tract carbohydrate digestion. When dietary, animal, or environmental factors contribute to abnormal, excessive flow of fermentable carbohydrates from the small intestine, hindgut acidosis can occur. Hindgut acidosis is characterized by increased rates of production of short-chain fatty acids including lactic acid, decreased digesta pH, and damage to gut epithelium as evidenced by the appearance of mucin casts in feces. Hindgut acidosis is more likely to occur in high-producing animals fed diets with relatively greater proportions of grains and lesser proportions of forage. In these animals, ruminal acidosis and poor selective retention of fermentable carbohydrates by the rumen will increase carbohydrate flow to the hindgut. In more severe situations, hindgut acidosis is characterized by an inflammatory response; the resulting breach of the barrier between animal and digesta may contribute to laminitis and other disorders. In a research setting, effects of increased hindgut fermentation have been evaluated using pulse-dose or continuous abomasal infusions of varying amounts of fermentable carbohydrates. Continuous small-dose abomasal infusions of 1 kg/d of pectin or fructans into lactating cows resulted in decreased diet digestibility and decreased milk fat percentage without affecting fecal pH or VFA concentrations. The decreased diet digestibility likely resulted from increased bulk in the digestive tract or from increased digesta passage rate, reducing exposure of the digesta to intestinal enzymes and epithelial absorptive surfaces. The same mechanism is proposed to explain the decreased milk fat percentage because only milk concentrations of long-chain fatty acids were decreased. Pulse-dose abomasal fructan infusions (1 g/kg of BW) into steers resulted in watery feces, decreased fecal pH, and increased fecal VFA concentrations, without causing an inflammatory response. Daily 12-h abomasal infusions of a large dose of starch (~4 kg/d) have also induced hindgut acidosis as indicated by decreased fecal pH and watery feces. On the farm, watery or foamy feces or presence of mucin casts in feces may indicate hindgut acidosis. In summary, hindgut acidosis occurs because of relatively high rates of large intestinal fermentation, likely due to digestive dysfunction in other parts of the gut. A better understanding of the relationship of this disorder to other animal health disorders is needed.

Carbohydrate source and protein degradability alter lactation, ruminal, and blood measures

Thirty-eight lactating dairy cows including 6 ruminally cannulated cows were used in a feeding study to assess effects of feed sources that differed in dietary nonfiber carbohydrate (NFC) composition and ruminal degradability of dietary protein (RDP) on production, ruminal, and plasma measures. The design was a partially balanced, incomplete Latin square with three 21-d periods and a 3 x 2 factorial arrangement of treatments. Samples and data were collected in the last 7 d of each period. Feed sources that differed in NFC profile were dry ground corn (GC; starch), dried citrus pulp (DCP; sugar and pectins), and sucrose+molasses (SM; sugar). Dietary RDP was altered by providing CP with soybean meal (+RDP) or substituting a heat-treated expeller soybean product for a portion of the soybean meal (-RDP). Diets were formulated to be isonitrogenous and similar in NFC concentration. Cows consuming GC had the greatest milk urea nitrogen and milk protein percentage and yield, tended to have the greatest dry matter intake, but had a lesser milk fat percentage compared with cows consuming DCP and SM. Sucrose+molasses diets supported greater dry matter intake, milk protein yield, and 3.5% fat- and protein-corrected milk yield than did DCP diets. On -RDP diets, milk protein percentage was less and milk urea nitrogen and protein yield tended to be less than for +RDP diets. Dry ground corn diverged from DCP and SM in the effect of NFC x RDP, with cows consuming GC having lesser milk yield, 3.5% fat- and protein-corrected milk yield, and efficiency with -RDP as compared with +RDP, whereas these production measures were greater with -RDP than +RDP for cows consuming DCP and SM. In contrast, in situ NDF digestibility at 30h for GC and SM was greater for -RDP as compared with +RDP, but the reverse was true for DCP. The lowest ruminal pH detected by 6h postfeeding was also influenced by the interaction of NFC x RDP, with cows consuming SM having a lower pH with +RDP than with -RDP and cows consuming DCP having a similar pH on either RDP treatment. Total rumen volatile fatty acid concentrations did not differ among diets, but acetate molar percent was greater for DCP than for SM, and GC had the lowest molar percent for butyrate and valerate and greatest branched-chain volatile fatty acid concentration. Valerate molar percent and NH(3) concentration tended to be greater with +RDP than with -RDP. Plasma glucose and insulin were both greater in cows receiving SM than in those receiving DCP. Protein degradability, NFC source, and their interactions affected lactation, ruminal, and blood measures, suggesting that these dietary factors warrant further consideration in diet formulation.

Nutrient synchrony: sound in theory, elusive in practice

The concept of improving animal performance by going beyond simply meeting requirements and synchronizing ruminal availability of protein and energy has been with us for at least 3 decades. Although theoretically appealing, research and field results have not supported this approach to diet formulation. Why? Essential to successful ruminal synchrony is the ability to predict available amounts and fates of diverse substrates. The substrates come from varied sources; their efficiencies of use and yields of products are affected by inherent properties, interactions, transformations, and passage. However, substrate quality and availability in the rumen are affected only in part by diet. For example, NPN, true protein, and peptides are contributed by diet and intraruminal recycling, with additional endogenous NPN contributions by the cow. Changes in factors that alter the rate or extent of substrate fermentation, such as the rate of passage or ruminal pH, can alter nutrient yield from the rumen and must be accounted for in order for synchrony to work. Our ability to estimate ruminally available substrate is also challenged by normal variation in feed composition and imprecision in component and digestibility analyses. Current in vitro assays may not be adequate to accurately describe the digestibility of feed components in vivo in mixed diets. There are some indications that the amount or pattern of supply of fermentable carbohydrate has a greater impact on microbial production and efficiency than does the pattern of protein supply. Animal responses to modifications in the supply of true protein from the rumen may be masked if additional protein is oxidized by tissues or if AA from endogenous sources cover deficiencies. Animal factors, such as response to immune challenge and sustained damage to tissues, will also affect partitioning of nutrients for production and may alter an animal's response to changes in nutrient supply. With the array of factors internal and external to the diet that must be considered, "synchrony" implies a greater deliberate precision in diet manipulation than may be currently possible to effect. Perhaps we should consider balance. Within the rumen and cow, can we generate conditions so that needed substrates or nutrients are available from the diet or accessible from endogenous resources to meet requirements and enhance productivity and efficiency? This approach involves the whole animal, rather than only the rumen and feed we offer to the cow.

Sucrose concentration alters fermentation kinetics, products, and carbon fates during in vitro fermentation with mixed ruminal microbes1

Effects of sucrose (Suc) concentration on fermentation kinetics and products were evaluated using 3 concentrations of Suc, with 1 concentration of isolated NDF from Bermudagrass fermented together in batch culture in vitro with rumen inoculum. Fixed amounts of medium and inoculum were the protein sources, so protein:Suc decreased with increasing Suc. Kinetics were calculated from gas production over 48 h in a randomized complete block design (n = 28), and product yield was evaluated with sampling every 4 h for 24 h in a split-split plot in time design (n = 84). Fermentation vial was the experimental unit. Increasing Suc increased the lag time of rapidly (P < 0.01) and slowly fermented (P < 0.01) fractions and tended to decrease the rate of gas production from the rapid fraction (P = 0.07). Gas production from the slow fraction decreased linearly with increasing Suc (P = 0.02), suggesting a decrease in NDF fermentation. Sucrose was the predominant substrate at </=8 h of fermentation. Maxima for microbial CP (MCP) production were detected at </=8 h of fermentation. At detected MCP maxima, MCP production increased linearly (P = 0.02) and total organic acids (sum of lactate, acetate, propionate, and butyrate; mmol) tended to increase linearly (P = 0.07) with increasing Suc. Maximum lactate production at 0 and 4 h increased (P = 0.01), and yield of lactate from Suc tended to increase, linearly (P = 0.09) with increasing Suc. At detected MCP maxima, yield of C in products (total organic acids, MCP, CO(2), CH(4), glycogen) from utilized Suc C declined linearly for total products (P = 0.01) and organic acids (P = 0.01) and tended to decline for MCP (P = 0.12) as Suc increased. This may be a function of increased catabolic inefficiency of microbes with increasing Suc, as evidenced by increasing yields of lactate, or the use of C for products not measured. Product C yields were 1.28, 0.98, and 0.81 from lowest to greatest Suc inclusion, respectively. Values >1 indicate incorporation of C from the medium, likely from AA and peptides. The results support the premises that direct effects of Suc concentration and perhaps protein:Suc alter yields of fermentation products. That substrate concentration altered fermentation products and kinetics, possibly due to interactions with the run conditions, advises the clear definition of substrates and fermentation conditions to determine how the results integrate into our knowledge of ruminant nutrition.

Integration of Ruminal Metabolism in Dairy Cattle

An important objective is to identify nutrients or dietary factors that are most critical for advancing our knowledge of, and improving our ability to predict, milk protein production. The Dairy NRC (2001) model is sensitive to prediction of microbial protein synthesis, which is among the most important component of models integrating requirement and corresponding supply of metabolizable protein or amino acids. There are a variety of important considerations when assessing appropriate use of microbial marker methodology. Statistical formulas and examples are included to document and explain limitations in using a calibration equation from a source publication to predict duodenal flow of purine bases from measured urinary purine derivatives in a future study, and an improved approach was derived. Sources of specific carbohydrate rumen-degraded protein components probably explain microbial interactions and differences among studies. Changes in microbial populations might explain the variation in ruminal outflow of biohydrogenation intermediates that modify milk fat secretion. Finally, microbial protein synthesis can be better integrated with the production of volatile fatty acids, which do not necessarily reflect volatile fatty acid molar proportions in the rumen. The gut and splanchnic tissues metabolize varying amounts of volatile fatty acids, and propionate has important hormonal responses influencing milk protein percentage. Integration of ruminal metabolism with that in the mammary and peripheral tissues can be improved to increase the efficiency of conversion of dietary nutrients into milk components for more efficient milk production with decreased environmental impact.

Efficiency of converting nutrient dry matter to milk in Holstein herds

Production of milk from feed dry matter intakes (DMI), called dairy or feed efficiency, is not commonly measured in dairy herds as is feed conversion to weight gain in swine, beef, and poultry; however, it has relevance to conversion of purchased input to salable product and proportion of dietary nutrients excreted. The purpose of this study was to identify some readily measured factors that affect dairy efficiency. Data were collected from 13 dairy herds visited 34 times over a 14-mo period. Variables measured included cool or warm season (high ambient temperature <21 degrees C or >21 degrees C, respectively), days in milk, DMI, milk yield, milk fat percent, herd size, dietary concentrations (DM basis) and kilograms of crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and forage. Season, days in milk, CP % and forage % of diet DM, and kilograms of dietary CP affected dairy efficiency. When evaluated using a model containing the significant variables, dairy efficiency was lower in the warm season (1.31) than in the cool season (1.40). In terms of simple correlations, dairy efficiency was negatively correlated with days in milk (r = -0.529), DMI (r = -0.316), forage % (r = -0.430), NDF % (r = -0.308), and kilograms of forage (r = -0.516), NDF (r = -0.434), and ADF (r = -0.313), in the diet, respectively. Dairy efficiency was positively correlated with milk yield (r = 0.707). The same relative patterns of significance and correlation were noted for dairy efficiency calculated with 3.5% fat-corrected milk yield. Diets fed by the herds fell within such a small range of variation (mean +/- standard deviation) for CP % (16.3 +/- 0.696), NDF % (33.2 +/- 2.68), and forage % (46.9 +/- 5.56) that these would not be expected to be useful to evaluate the effect of excessive underfeeding or overfeeding of these dietary components. The negative relationships of dairy efficiency with increasing dietary fiber and forage may reflect the effect of decreased diet digestibility. The results of this study suggest that managing herd breeding programs to reduce average days in milk and providing a cooler environment for the cows may help to maximize dairy efficiency. The mechanisms for the effects of the dietary variables on dairy efficiency need to be understood and evaluated over a broader range of diets and conditions before more firm conclusions regarding their impact can be drawn.

Challenges with nonfiber carbohydrate methods1,2

Nonfiber carbohydrates (NFC) encompass a compositionally and nutritionally diverse group exclusive of those carbohydrates found in NDF. Their content in feeds has often been described as a single value estimated by difference as 100% of dry matter minus the percentages of CP, NDF (adjusted for CP in NDF), ether extract, and ash. A calculated value was used because of difficulties with assays for individual NFC, but it does not differentiate among nutritionally distinct NFC. Errors in NFC estimation can arise from not accounting for CP in NDF and when multipliers other than 6.25 are appropriate to estimate CP. Analyses that begin to distinguish among NFC are those for starch, soluble fiber (non-NDF, nonstarch polysaccharides), and low molecular weight carbohydrates (mono- and oligosaccharides). Many starch analyses quantify alpha-glucans through specific hydrolysis of alpha-(1 --> 4) and alpha-(1 --> 6) linkages in the glucan, and measurement of released glucose. Incomplete gelatinization and hydrolysis will lead to underestimation of starch content. Starch values are inflated by enzyme preparations that hydrolyze carbohydrates other than alpha-glucan, measurement of all released monosaccharides without specificity for glucose, and failure to exclude free glucose present in the unhydrolyzed sample. Soluble fiber analyses err in a fashion similar to NFC if estimation of CP requires multipliers other than 6.25, or if contaminants such as CP and starch have not been properly accounted. Depolymerization and incomplete precipitation can also decrease soluble fiber estimates. The low molecular weight carbohydrates have been defined as carbohydrates soluble in 78 to 80% ethanol, which separates them from polysaccharides. They can be measured in extracts using broad-spectrum colorimetric assays (phenol-sulfuric acid assay or reducing sugar analysis of acid hydrolyzed samples) or chromatographic methods. Limitations of the colorimetric assays include lack of differentiation among mono- and oligosaccharides and differences in efficacy of measuring total carbohydrate. More sensitive and precise chromatographic methods require expensive equipment and specialized expertise. Current methods for NFC can separate nutritionally relevant fractions, but questions remain as to which fractions merit analysis and what analyses to use. These issues must be resolved in order to soundly evaluate and explore the roles of carbohydrates in diets.

Metabolic responses of transition Holstein cows fed anionic salts and supplemented at calving with calcium and energy

The objective of this study was to determine the concentrations of plasma Ca, P, Mg, nonesterified fatty acids (NEFA), 3-hydroxybutyrate (BHBA), and glucose in transition cows fed anionic salts prepartum and provided with calcium and energy supplements at calving. The study was conducted on a Florida Holstein dairy farm from November to December 1997. Treatments consisted of no treatment (n = 30); 60 g of Ca as calcium chloride, orally (n = 30); 110 g of Ca as calcium propionate 510 g plus 400 g of propylene glycol, orally (n = 30); two doses of 60 g of Ca as calcium chloride, one at calving and the second 24 h later, orally (n = 30); and 10 g of Ca as borogluconate, intravenously (n = 30). Treatments were administered within 12 h after parturition. Blood samples were collected at d 1 (parturition), 2, 3, 6, 9, and 12 after calving. Plasma total Ca, P, Mg, NEFA, BHBA, and glucose were measured. There were no differences in the concentrations of the blood metabolites among treatments.

Modeling the active sites in metalloenzymes 5. The heterolytic bond cleavage of H(2) in the [NiFe] hydrogenase of desulfovibrio gigas by a nucleophilic addition mechanism

The H(2) activation catalyzed by an Fe(II)-Ni(III) model of the [NiFe] hydrogenase of Desulfovibrio gigas has been investigated by density functional theory (DFT/B3LYP) calculations on the neutral and anionic active site complexes, [(CO)(CN)(2)Fe(mu-SH)(2)Ni(SH)(SH(2))](0) and [(CO)(CN)(2)Fe(mu-SH)(2)Ni(SH)(2)](-). The results suggest that the reaction proceeds by a nucleophilic addition mechanism that cleaves the H-H bond heterolytically. The terminal cysteine residue Cys530 in the [NiFe] hydrogenase active site of the D. gigas enzyme plays a crucial role in the catalytic process by accepting the proton. The active site is constructed to provide access by this cysteine residue, and this role explains the change in activity observed when this cysteine is replaced by a selenocysteine. Furthermore, the optimized geometry of the transition state in the model bears a striking resemblance to the geometry of the active site as determined by X-ray crystallography.

Differences in yields of microbial crude protein from in vitro fermentation of carbohydrates

The yield of microbial crude protein (CP) from carbohydrate fermentations was examined using trichloroacetic acid (TCA) precipitation of batch cultures. The medium contained ammonium bicarbonate, casein acid hydrolysate, and cysteine hydrochloride as nitrogen sources. Isolated bermudagrass neutral detergent fiber (iNDF) and 60:40 blends of iNDF and sucrose (Suc), citrus pectin (Pec), or corn starch (Sta) (approximately 375 mg of substrate organic matter/vial) were fermented in vitro in two separate fermentation runs with mixed ruminal microbes. Three fermentation tubes for each substrate were destructively sampled at 0, 4, 8, 12, 16, 20, and 24 h. Fermented samples were precipitated at a concentration of 19.4% TCA, and filtered to collect unfermented iNDF and precipitate. Collected residues were analyzed for CP as Kjeldahl N x 6.25. Microbial CP (TCACP) was estimated as TCA-precipitated CP corrected for the TCA-precipitated CP content of substrates at 0 h, and the mean of fermentation blanks from each hour. Medium pH did not decline below 6.49 in any fermentation tube. Comparisons of maximal yields based on the hour in which the measured mean yield was greatest for each substrate in each fermentation indicated that Sta > Suc = Pec > iNDF (P < 0.05). All substrates showed increases in TCACP to their maxima, followed by declines in TCACP. This likely reflects the relative dominance of production or degradation of microbes about the point of substrate limitation. Unlike other substrates, Suc had no detectable lag, and presented a more persistent TCACP yield curve than the other non-NDF carbohydrates (NFC). Regression analysis of TCACP yield over time for iNDF versus other substrates, Pec + Sta versus Suc, and Pec versus Sta indicated that the compared curves were not parallel (P < 0.05). The patterns of TCACP yield over time were cubic for iNDF and Suc, and quartic for Pec and Sta. The maximal yields of TCACP predicted from the regressions were Sta: 34.0 mg at 15.6 h, Pec: 29.9 mg at 13.5 h, Suc: 25.5 mg at 12.6 h, and iNDF: 13.6 mg at 19.3 h. The NDF and NFC carbohydrates examined differed in both maximal yields and temporal patterns of yield of TCACP.

Minimum energy structure of hydridotris(pyrazolyl)borato iridium(V) tetrahydride is not a C(3upsilon) capped octahedron

Recent synthesis and NMR spectroscopy of neutral Ir(V) complexes hydridotris(3,5-dimethylpyrazol-1-yl)borato tetrahydride (Tp*IrH(4)) and hydridotris(pyrazol-1-yl)borato tetrahydride (TpIrH(4)) have been interpreted as supporting face-capped octahedral structures (C(3upsilon)) with each of three Ir-H bonds trans to an Ir-N bond and the fourth hydride capping the IrH(3) face. Here, density functional geometry optimizations and coupled cluster calculations on hydridotris(pyrazol-1-yl)borato iridium tetrahydrogen find that a C(s) edge-bridged octahedral tetrahydride structure and a C(1) eta(2)-dihydrogen, dihydride structure are local minima and find that the C(3upsilon) structure is a local maximum (second-order saddle point). Several low energy transition states connecting the local minima have been located, and these minima can be used to simulate the experimental NMR spectra. A comparison of the experimental infrared spectrum of Tp*IrH(4) and the harmonic frequency calculations on the C(s), C(1), and C(3upsilon) structures also supports the assignment of the C(s)and C(1) structures as the observed ones.

Effects of carbohydrates from citrus pulp and hominy feed on microbial fermentation in continuous culture

Eight dual-flow continuous-culture fermenters were used to evaluate the effect of neutral detergent-soluble carbohydrates (NDSC) on fermentation by ruminal microorganisms. Citrus pulp and hominy feed were added to a basal diet as sources of NDSC, with citrus pulp providing neutral detergent-soluble fiber (NDSF) in the form of pectic substances and with hominy feed in the form of starch. The basal diet contained 26.7% corn silage, 6.0% alfalfa hay and 3.8% cottonseed hulls on a DM basis. The dried citrus pulp diet contained on a DM basis 17.2% CP, 34.7% NDF, 33.7% NDSC, and 14.4% NDSF, whereas the hominy feed diet contained 17.9% CP, 33.2% NDF, 35.9% NDSC, and 8.8% NDSF. Organic matter, DM, and NDF and ADF digestion were not affected by source of carbohydrate. Ammonia N concentration was greater (P < 0.05) for the hominy feed diet (14.2 mg/100 mL) than for the dried citrus pulp diet (9.3 mg/100 mL). Total N, nonammonia N, microbial N, and dietary N flows were not affected by treatments; however, the efficiency of microbial protein synthesis was greater (P = 0.055) for the dried citrus pulp diet than for the hominy feed diet (30.6 vs 27.8 g of bacterial N/kg of OM truly digested). Results from this experiment indicate that NDSF from citrus pulp can provide similar sources of energy compared with starch from hominy feed to support ruminal microbial growth.

Effects of prepartum dry matter intake and forage percentage on postpartum performance of lactating dairy cows

The objective of this research was to determine whether different dry matter intakes (DMI) or forage percentages prepartum would have an impact on postpartum performance. Multiparous Holstein cows (n = 41) received either high (H) or low (L) forage rations that were fed free choice (F) or restricted (R), i.e., HF, HR, LF, and LR. The L rations were higher in net energy of lactation and lower in neutral detergent fiber concentrations. After calving, all cows were fed the same ration ad libitum. Prepartum DMI were 8.0 for R versus 12.4 kg/d for F with LF greater than HF (14.1 vs. 10.7 kg/d). Prepartum treatments did not affect postpartum means for DMI, milk yield, milk protein percentage, body weight, body condition score, or plasma glucose concentrations (overall means 1 to 40 DIM were, respectively, 21.1 kg/d, 34.0 kg/d, 3.03%, 624 kg, 3.2, and 66 mg/dl). However, curves from 1 to 40 DIM showed that DMI and milk yield were slightly higher in early lactation in cows whose DMI had been restricted prepartum but mean milk fat percentage was lower (3.10 vs. 3.42%). Plasma NEFA were higher and insulin lower in H versus L before and after calving. High DMI prepartum, at best, showed no advantage over restricted feeding.

Effects of nitrogen fertilization and harvest date on yield, digestibility, fiber, and protein fractions of tropical grasses

To evaluate the response of three tropical forage species to varying rates of nitrogen (N) fertilization [0, 39, 78, 118, 157 kg of N/(ha x cutting)] and five summer harvests, forage DM mass and nutritive value were evaluated in a randomized complete block design with a split-split plot arrangement of treatments. Plots (n = 60) were established in 1996, and five harvests were conducted every 28 d from June through September in 1997 and 1998, with fertilizer applications occuring after each harvest. Fertilization with 78 kg of N/(ha x cutting) increased forage mass in these grasses by 129% (P < 0.01) compared with no N fertilization. Additional N did not result in further increases of forage mass. Bermudagrass (Cynodon dactylon) produced more forage DM [P < 0.01; 1,536 +/- 43 kg/(ha x cutting)] than stargrass [Cynodon nlemfuensis; 1,403 +/- 43 kg/(ha x cutting)] or bahiagrass [Paspalum notatum; 1,297 +/- 43 kg/(ha x cutting)]. Peak forage mass for all species occurred in late June and July. In vitro organic matter digestibility (IVOMD) of stargrass increased (P < 0.01) linearly with fertilization. A quadratic response to N fertilization (P < 0.01) was noted in IVOMD of bermudagrass, whereas bahiagrass was not affected. Bermudagrass was more (P < 0.01) digestible (57.5 +/- 0.4) than stargrass (54.6 +/- 0.4) and bahiagrass (51.9 +/- 0.4%). As fertilization level increased, NDF decreased linearly (P < 0.01) in all three forages. Total N concentration increased (P < 0.01) linearly as N fertilization increased in all forages. Total N concentration was highest (P < 0.01) in stargrass (2.4%, DM basis) compared with bermudagrass (2.2%) and bahiagrass (2.0%). Total N concentration was depressed in all forages for late June and July harvests (P < 0.01). Fertilization increased (P < 0.05) the concentration (% of DM) of all protein fractions. In July and August, nonprotein N was reduced 11.8% (P < 0.01), whereas ADIN increased in July (P < 0.01). Bahiagrass had less N in cell contents than did bermudagrass and stargrass but had a greater concentration of N associated with the cell wall. Managerial factors, including rates of N fertilization and harvest dates, can have profound effects on the nutritional value of forage. An increased understanding of these effects is imperative to improve supplementation programs for ruminants.

An assessment of the effectiveness of the Mottep model for increasing donation rates and preventing the need for transplantation--adult findings: program years 1998 and 1999

The National Minority Organ Tissue Transplant Education Program (MOTTEP) evaluated the effects of a community-implemented health education program for adult members of minority population groups to affect attitude, knowledge, and intent to change behavior. In addition, this study represents 1 of the first major initiatives to formally address prevention as a strategy to contribute to reducing the need for organ/tissue transplantation among minorities in the United States. The study targeted students (youth) and adults representing different ethnic groups (African-Americans, Alaskan Natives, Filipinos, Latinos, and Native Americans) who attended health education presentations addressing organ tissue donation, transplantation, and illness prevention in 15 different cities in churches, schools, and other sites. A cross-sectional study that used questionnaires was designed for collecting data from all participants. This article presents data on the adult sample only. Preintervention and postintervention data were collected from 914 adult participants to determine any immediate effects of the intervention. By using data from matched sets of the preintervention and postintervention questionnaires for all adult participants, there were significant increases in (P < or =.000) trust in doctors, future plans to become organ donors, and in participants' spiritual/religious beliefs about organ/tissue donation. There was also a significant increase (P <.05) in participants' awareness of the perceived need for organ/tissue donation. African-American participants were significantly more likely (P < or =.000) to report trust in doctors, future plans to donate organs/tissue, and perceive the need for donation as a result of MOTTEP presentation. Caucasian participants showed a significant increase (P < or =.007) in trust in doctors, perceived need for organ donation (P < or =.05), and in shifting spiritual/religious beliefs about organ/tissue donation (P < or =.02). Attitudes, knowledge, beliefs, and behavioral intentions about organ/tissue donation and illness prevention can be affected by culturally appropriate health education programs designed for targeted population groups. Sustained changes in behavioral intentions toward organ donation and illness prevention may require multiple educational interventions in different community settings to increase donation rates and improve behavioral health practices to prevent illness.

A theoretical study of the primary oxo transfer reaction of a dioxo molybdenum(VI) compound with imine thiolate chelating ligands: a molybdenum oxotransferase analogue

The reaction mechanism of an analogue system of the molybdenum oxotransferases was investigated at the density functional (B3P86) level of theory. Kinetic measurements by Schultz and Holm suggest that the reaction MoO(2)(t-BuL-NS)(2) + X --> MoO(t-BuL-NS)(2) + OX (t-BuL-NS = bis(4-tert-butylphenyl)-2-pyridylmethanethiolate(1-)) occurs through an associative transition state. Our results on the model reaction, MoO(2)(SCH(2)CHNH)(2) + P(CH(3))(3) --> MoO(SCH(2)CHNH)(2) + OP(CH(3))(3), support this hypothesis, and indicate that this reaction proceeds through a two-step mechanism via an associative intermediate. The DeltaH(++) for the first, and rate-determining, step was predicted to be 9.4 kcal/mol, and DeltaH(++) for the second step (release of the OP(CH(3))(3) product) was predicted to be 3.3 kcal/mol. These results are in good agreement with the experimental system, for which the rate determining DeltaH(++) = 9.6(6) kcal/mol. Shultz and Holm's experimental model undergoes a significant ligand rearrangement in the oxo transfer reaction: the reactant, MoO(2)(t-BuL-NS)(2), has a trans-S arrangement of the ligands, while the product, MoO(t-BuL-NS)(2), has a trans-N arrangement. To investigate the driving force behind the ligand rearrangement, four model compounds, that systematically removed the unsaturation at the N and the chelate character of the ligands, were modeled at the B3P86 level of theory. For all models of the dioxo species, the trans-N isomer was higher in energy than the trans-S isomer. The analysis of these results indicated that a trans influence accounts for approximately 16% of the energy difference, the unsaturation at the nitrogens accounts for approximately 26%, and the ring strain from the chelator accounts for approximately 58% of the energy difference between the two isomers (trans-N and trans-S). For all models of the monooxo species, only the trans-N species was a stable geometry. Therefore, for the reverse oxo transfer reaction, ligand rearrangement must occur after or during the attack of the OX substrate.