Degradable Fraction Research Articles

Comparison of various pretreatment strategies and their effect on chemistry and structure of sugar beet pulp

Abstract Pretreatment is deemed as a key step to destroy biomass recalcitrance and improve enzyme accessibility to cellulose during the second generation bioethanol production. A series of pretreatments were applied to treat sugar beet pulp (SBP) to uncover their impact on chemical and structural changes, and enzymatic digestibility. The results showed that all the four pretreatments had effects on the physical structure and chemical compositions of SBP. When being subjected to aqueous ammonia pretreatment, SBP exhibited high cellulose content due to the degradation of neutral detergent soluble fraction and other amorphous components. FTIR analysis showed that aqueous ammonia pretreatment could cleave ester linkages between carbohydrates and lignin, and modify the phenolic hydroxyl in lignin, yet without obvious delignification. In addition, the aqueous ammonia pretreatment led to cell wall dislocation and lignin redistribution, and enhanced enzymatic hydrolysis. The results obtained here indicated that biomass recalcitrance was destroyed by morphological and chemical alternation. The reducing sugar yield of SBP pretreated by AA could reach 487.8 mg/g, which was 2.73 times higher than that of the control. Consequently, AA might be more suitable to pretreatment for SBP, compared to the other pretreatments.

Ruminal Ca and P Releases from Diets with Different Portion of the Sugarcane Bagasse

The in sacco technique was used to study the ruminal Ca and P releases from diets with different portion of sugarcane bagasse. Three diets containing 15, 25, and 35% of sugarcane bagase were tested their kinetic of ruminal Ca and P degradabilities. Two adult male sheep fitted with rumen cannula were used in the in sacco technique. In the in sacco experiment, feed samples were placed in the nylon bag and inserted into ruminal cannula for 0, 1, 3, 6, 12, 24, and 48 h. The kinetic of ruminal Ca and P degradabilities were focused on rapidly soluble fraction (fraction a), potentially degradable fraction (fraction b), and the degradation rate of fraction b (c). The data were tested using analyse of variance based on a completely randomized design. While the portion of sugarcane bagasse increased (P<0.05) fraction a of Ca diet, the portion b of P diet was decreased (P<0.05) by the portion of sugarcane bagasse.In conclusion, the effect of increasing portion of sugarcane bagasse in diet on ruminal release of Ca may be differed with that ofthe ruminal P release.

Impact of Thermal Degradation of Cyanidin-3-O-Glucoside of Haskap Berry on Cytotoxicity of Hepatocellular Carcinoma HepG2 and Breast Cancer MDA-MB-231 Cells.

Cyanidin-3-O-glucoside (C3G), the predominant anthocyanin in haskap berries (Lonicera caerulea L.), possesses antioxidant and many other biological activities. This study investigated the impact of temperature and pH on the degradation of the C3G-rich haskap fraction. The effect of the thermal degradation products on the viability of hepatocellular carcinoma HepG2 and breast cancer MDA-MB-231 cells was also studied in vitro. Using column chromatography, the C3G-rich fraction was isolated from acetone extracts of haskap berries. The C3G stability in these fractions was studied under elevated temperatures (70 °C and 90 °C) at three different pH values (2.5, 4, and 7) by monitoring the concentration of C3G and its major degradation products, protocatechuic acid (PCA) and phloroglucinaldehyde (PGA), using liquid chromatography mass spectrometry. Significant degradation of C3G was observed at elevated temperatures and at neutral pH. Conversely, the PCA and PGA concentration increased at higher pH and temperature. Similar to C3G, neutral pH also has a prominent effect on the degradation of PGA, which is further accelerated by heating. The C3G-rich fraction exhibited dose-dependent inhibitory effects on cell metabolic activity when the HepG2 cells were exposed for 48 h. Interestingly, PGA but not PCA exhibited cytotoxic effects against both MDA-MB-231 and HepG2 cells. The results suggest that thermal food processing of haskap could influence its biological properties due to the degradation of C3G.

Evaluation of ruminal crude protein degradation of common feeds used in temperate climates

The objective of this study was to evaluate the nutritional value of different feeds using chemical analysis and procedures to determine the nitrogen fractions expressed in g/kg of crude protein (CP) using a Cornell system. The experiment includes samples of common feeds used for ruminants in the Czech Republic. Fraction A is most commonly available from silages (average 468.2 g/kg CP) and least available in soybean (83.9 g/kg CP). In contrast, rapidly degradable protein (fraction B1) showed the lowest values in silages (average 31.5 g/kg CP) and the highest values in rapeseed cakes (average 195.7 g/kg CP) and lupines (average 308.7 g/kg CP). The intermediately degradable protein fraction B2 had a high value in almost all of the samples and especially in lupines (average B2 fraction 384.7 g/kg CP). The remaining fractions (B3 and C) represent slowly degraded proteins and unavailable proteins and represented a very small part of CP (average 18.9 and 34.9 g/kg CP, respectively). A strong relationship was found between fraction A and soluble protein (SOLP) and fraction B1 and SOLP. Other strong correlations were found between fraction B2 and CP, B2 and insoluble protein (IP), B3 and IP and B3 and neutral detergent insoluble nitrogen (NDIN).

Samanlarda Biyolojik Muamelelerle Lignoselüloz Kompleksin Sindirilebilirliğinin Artırılması

Samanların hücre duvarında bulunan lignoselüloz kompleksin parçalanması ile selüloz ve hemiselüloz gibi rumen fermantasyonuyla sindirilebilir fraksiyonlar elde edilir. Rumende sindirilmeyen ligninin biyoteknolojik metotlarla parçalanarak samandan yararlanılabilirliğin artırılması son yıllarda hayvan beslemecilerin odak noktası olan alanlarından birisi olmuştur. Lignoselüloz kompleksin biyolojik metotlarla muamelesinde bakteriler, mantarlar ve bu mikroorganizmalardan elde edilen enzimler kullanılmaktadır. Bakteri muamelesinde Mycobacterium, Arthrobacter ve Flavobacterium türü bakterilerin lignini parçalayabilme özelliğinden yararlanılmaktadır. Enzim muamelesi etkili olmasına rağmen yüksek maliyet nedeniyle uygulamada yer bulamamıştır. Mantar muamelesinde beyaz, kahverengi ve yumuşak çürüme yapan 3 tür mantar kullanılmaktadır. Kahverengi çürükçül mantarlar tercihen selüloz ve hemiselüloza saldırır, ancak lignini parçalayamaz. Beyaz çürükçül mantarlar lignine saldırarak lignol bağları ve aromatik halkayı parçalarlar. Beyaz çürükçül mantarlar selülaz, ksilanaz gibi hidrolitik enzimlerle polisakkaritleri ve lignin peroksidaz ve lakkaz gibi oksidatif ligninolitik enzimlerle lignini parçalarlar. Lignoselülozik materyalleri en iyi parçalayabilen mikroorganizmaların mantarlar olması ve maliyetin düşük olması nedeniyle özellikle beyaz çürükçül mantarların uygulama potansiyeli bulunmaktadır. Bu bildiride biyoçeşitliliğin sağladığı avantajla biyolojik metotlarla samanların sindirilebilirliğinin artırılması tartışılacaktır.

Effects of partial or total replacement of corn cracked grain with high concentrations of crude glycerin on rumen metabolism of crossbred sheep

Crude glycerin, a by-product of the biodiesel industry, has been used as a strategic ingredient in intensive ruminant production systems, mainly in substitution of starch-rich ingredients. The present study was performed to evaluate the effects of the inclusion of up to 30% of crude glycerin in diets for feedlot sheep, on ruminal parameters, such as pH, NH3-N and volatile fatty acids concentrations, in situ degradability, as well as in vitro greenhouse gas production and in vitro digestibility. Eight ruminally-cannulated male Santa Inês × Dorper sheep (64.5 ± 8.5 kg) were distributed in a replicated 4 × 4 Latin square design. The experimental diets contained 0, 10, 20 or 30% of crude glycerin and were labeled as G0, G10, G20 and G30, respectively. The crude glycerin totally replaced the corn cracked grain in treatment G30. The inclusion of crude glycerin in the diets tended to promote a quadratic effect in DMI, with greater values observed for treatments G10 and G20. Crude glycerin tended to increase the ruminal pH and NH3-N, but linearly reduced the total molar concentration of VFA, acetic, butyric, isobutyric and isovaleric acids. Treatments linearly increased in vitro DM digestibility of diets and linearly reduced NDF digestibility. The inclusion of crude glycerin in the diets linearly decreased the in vitro total gas and CO2 production (mL/g degraded) and tented to reduce CH4 (mL/g degraded). A linear increase of soluble fraction in water (“a”) of the diets was observed with the increasing inclusion of crude glycerin. The insoluble but potentially degradable fraction (“b”) of DM and NDF of the diets were linearly decreased and increased, respectively. The potential ruminal degradation of the diets was markedly and linearly increased with the increasing inclusion of the by-product. The replacement of corn cracked grain by crude glycerin (up to 30% DM) changes rumen fermentation parameters, decreasing VFA production, in vitro total gas production and CH4. Additionally, the potential and effective degradation as well as in vitro DM digestibility of diets are improved while fiber digestibility is impaired.

Sequential and simultaneous strategies for biorefining of wheat straw using room temperature ionic liquids, xylanases and cellulases

Sequential and simultaneous strategies for fractioning wheat straw were developed in combining 1-ethyl-3-methyl imidazolium acetate [C2mim][OAc], endo-xylanases from Thermobacillus xylanilyticus and commercial cellulases. After [C2mim][OAc]-pretreatment, hydrolysis catalyzed by endo-xylanases of wheat straw led to efficient xylose production with very competitive yield (97.6 ± 1.3%). Subsequent enzymatic saccharification allowed achieving a total degradation of cellulosic fraction (>99%). These high performances revealed an interesting complementarity of [C2mim][OAc]- and xylanase-pretreatments for increasing enzymatic digestibility of cellulosic fraction in agreement with the structural and morphological changes of wheat straw induced by each of these pretreatment steps. In addition a higher tolerance of endo-xylanases from T. xylaniliticus to [C2mim][AcO] until 30% v/v than cellulases from T. reesei was observed. Based on this property, a simultaneous strategy combining [C2mim][OAc]- and endo-xylanases as pretreatment in a one-batch produced xylose with similar yield than those obtained by the sequential strategy.

Samanlarda Biyolojik Muamelelerle Lignoselüloz Kompleksin Sindirilebilirliğinin Artırılması

The efforts to break down the lignocellulosic complex found in the cell wall of straws, besides digestible cellulose and hemicellulose by rumen fermentation, improvement of straw digestibility by the degradation of indigestible lignin fraction of complex by using of biotechnological methods is one of the focus areas of animal nutritionists in recent years. Biological method sare prefer redover other methods due to the environmental friendliness. In the biological treatment methods of lignocellulosic complex, biodiversity of bacteria, enzymes and fungi gives opportunity to select lignin degrading species. Mycobacterium, Arthrobacter and Flavobacterium genre bacteria are used to degrade lignin by bacterial treatment. Lignocellulolytic enzymes isolated from different varieties of fungi are used in enzyme treatment. There are 3 genres of fungus that are white, Brown and soft rot in fungal treatments. Brown rot fungi prefer ably attack cellulose and hemicelluloses, but not lignin. White rot fungi attack the lignin and break up lignol bonds and aromatic ring. White rot fungi break down polysaccharides with hydrolytic enzymes such as cellulase, xylanase, and lignin with oxidative ligninolytic enzymes such as lignin peroxidase and laccase. Because of the fact that the microorganisms that can break down the lignocellulosic materials are the fungi and the cost is low, the application of white rot fungi is possible. In this paper, improvement the lignocellulosic comlex digestibility of straw by biological treatment with the advantage of biodiversity is discussed.

Condensed tannin-amended cassava silage: fermentation characteristics, degradation kinetics andin-vitrogas production with rumen liquor

AbstractThe objective of the current research was to evaluate the fermentative characteristics of silage made with the upper third section of cassava (Manihot esculenta) plants with added condensed tannin levels of 0, 25, 50 and 75 g/kg dry matter (DM). The experimental design was a complete randomized design, with treatments arranged in a 4 × 7 factorial (tannin addition levels × days of ensiling). The loss of gas and the presence of moulds observed in the opening days had increased linearly. Fermentative characteristics were decreased by the addition of tannin. Acetic acid content showed a linear increase. Tannin levels had a quadratic effect on gas production at 28 days of ensiling. After 56 days, however, tannin levels had no significant effect on silage gas production. After 28 days of ensiling, the degradability of potentially degradable fraction ‘b’ demonstrated quadratic effect. The same occurred with the fractions ‘a’, ‘b’ which were undegradable after 56 days of ensiling. The addition of condensed tannin lengthened the fermentative stage and caused the silage to stabilize after 56 days of ensiling.

Wood waste decomposition in landfills: An assessment of current knowledge and implications for emissions reporting

Large quantities of wood products have historically been disposed of in landfills. The fate of this vast pool of carbon plays an important role in national carbon balances and accurate emission reporting. The Republic of Ireland, like many EU countries, utilises the 2006 Intergovernmental Panel on Climate Change (IPCC) guidelines for greenhouse gas reporting in the waste sector, which provides default factors for emissions estimation. For wood products, the release of carbon is directly proportional to the decomposition of the degradable organic carbon fraction of the product, for which the IPCC provides a value of 0.5 (50%). However, in situ analytic results of the decomposition rates of carbon in landfilled wood do not corroborate this figure; suggesting that carbon emissions are likely overestimated. To assess the impact of this overestimation on emission reporting, carbon decomposition values obtained from literature and the IPCC default factor were applied to the Irish wood fraction of landfilled waste for the years 1957–2016 and compared. Univariate analysis found a statistically significant difference between carbon (methane) emissions calculated using the IPCC default factor and decomposition factors from direct measurements for softwoods (F = 45.362, p = <.001), hardwoods (F = 20.691, p = <.001) and engineered wood products (U = 4.726, p = <.001). However, there was no significant difference between emissions calculated using only the in situ analytic decomposition factors, regardless of time in landfill, location or subsequently, climate. This suggests that methane emissions from the wood fraction of landfilled waste in Ireland could be drastically overestimated; potentially by a factor of 56. The results of this study highlight the implications of emission reporting at a lower tierand prompts further research into the decomposition of wood products in landfills at a national level.

EFFECT OF SOME TREATMENTS ON IN SITU DRY MATTER AND CRUDE PROTEIN DEGRADATION OF SOME RANGE PLANTS IN THE NORTH WEST COAST REGION, EGYPT

An experiment was conducted to evaluate the nutritive value of six dominant range plants in Wadi Hashim, North West Coast, Egypt, through the estimation of chemical composition and in situ dry matter (DM) and crude protein (CP) degradation kinetics. In addition, plants were treated by different processes, such as ensiling or addition of Poly Ethylene Glycol (PEG) in comparison with those without treatment (as fed). The plants belong to 6 families: Thymelaea hirsuta (family: Thymelaeaceae); Lycium shawii (f: Solanaceae); Asphodelus fistulosus (f: Liliaceae); Silybium marianum (f: Compositae); Pituranthos tortuosus (f: Umbelliferae) and Suaeda vermiculata (f: Chenopodiaceae). The DM and CP degradation kinetics were evaluated by the artificial fiber bag technique through in situ procedure, using three ruminally cannulated camels. Chemical composition of the studied plants showed that Suaeda vermiculata followed by Lycium shawii contained higher CP (12.8 and 11.9%, respectively). Treatments as ensiling process or treatment with PEG improved chemical composition of the experimental plants. Degradation profile of DM indicated that the higher values of the rapidly degradable fraction ‘a’ were recorded in S. marianum followed by A. fistulosus in all of their forms (as fed, silage or treated with PEG) while S. vermiculata recorded high value in silage form only (42.4%). The fraction ‘a’ was generally low across the studied plants as fed and those treated with PEG. However, the slowly degradable fraction ‘b’ differed among plant species, being high in A. fistulosus and S. marianum with 60.4, and 59.3% DM (as fed), 57.3 and 56.8% DM (treated with PEG) and 57.7 and 62.1% DM (when ensiled), respectively. Concerning the CP degradability, it was found that the soluble fraction “a” was low as in T. hirsute, P. tortuosus and S. vermiculata (as fed, 10.5, 21.7 and 23.5% CP, respectively) and it was irregularly affected with PEG addition to become 31.5, 23.5 and 19.6% CP, respectively, and slightly increased when ensiled to become 24.5, 23.4 and 31.2% CP, respectively. Meanwhile, the slowly fraction “b” was not affected in a uniform pattern when treated with PEG or ensiled. The slowly fraction was reduced in T. hirsute and A. fistulosus when treated with PEG or ensiled when compared with their values as fed. Results indicated that the contents of anti-nutritional factors, total and condensed tannins and saponin, in the studied plants were reduced with treatment, particularly ensiled ones. Based on these findings, it can be concluded that the nutritive value of the forage plant species are improved with treatment and can be used as supplement when ensiled.

Assessment of hydrocarbon degradation potentials in a plant–microbe interaction system with oil sludge contamination: A sustainable solution

ABSTRACTA pot culture experiment was conducted for 90 days for the evaluation of oil and total petroleum hydrocarbon (TPH) degradation in vegetated and non-vegetated treatments of real-field oil-sludge-contaminated soil. Five different treatments include (T1) control, 2% oil-sludge-contaminated soil; (T2), augmentation of microbial consortium; (T3), Vertiveria zizanioides; (T4), bio-augmentation along with V. zizanioides; and (T5), bio-augmentation with V. zizanioides and bulking agent. During the study, oil reduction, TPH, and degradation of its fractions were determined. Physico-chemical and microbiological parameters of soil were also monitored simultaneously. At the end of the experimental period, oil content (85%) was reduced maximally in bio-augmented rhizospheric treatments (T4 and T5) as compared to control (27%). TPH reduction was observed to be 88 and 89% in bio-augmented rhizospheric soil (T4 and T5 treatments), whereas in non-rhizospheric and control (T2 and T1), TPH reduction was 78 and 37%, respectively. Degradation of aromatic fraction after 90 days in bio-augmented rhizosphere of treatments T4 and T5 was found to 91 and 92%, respectively. In microbial (T2) and Vertiveria treatments (T3), degradation of aromatic fraction was 83 and 68%, respectively. A threefold increase in soil dehydrogenase activity and noticeable changes in organic carbon content and water-holding capacity were also observed which indicated maximum degradation of oil and its fractions in combined treatment of plants and microbes. It is concluded that the plant–microbe soil system helps to restore soil quality and can be used as an effective tool for the remediation of oil-sludge-contaminated sites.

Chemical composition, in vitro and in situ dry matter digestibility and preference of Quercus resinosa foliage

The objectives of this study were to determine the chemical composition and dry matter digestibility of Quercus resinosa leaves harvested at different seasons of the year and to assess the intake and palatability of lamb diets containing foliage of Q. resinosa. There were three sites of collection, two located in the state of Jalisco and one in the state of Zacatecas, México. The young leaves harvested in spring, had greatest (P &gt;0.05) nutritional value than leaves harvested in other seasons. The in vitro digestibility of organic matter (IVOMD), rapidly degradable fraction (a) and the degradation rate (c) were greater (P &gt;0.05) in leaves harvested in spring and winter. The slowly degradable fraction (b) was greater (P &gt;0.05) in spring, summer and autumn, and lesser in winter. The potential degradation fraction (a + b) and the effective degradability of dry matter were maximized (P &gt;0.05) in spring than in the other seasons. The consumption was similar (P &gt;0.05) among diets with different inclusion levels of leaves, but sheep consumed greater (P &gt;0.05) amounts of diet containing leaves collected in spring. In conclusion, the Q. resinosa foliage contains the nutritional value and the digestibility and palatability that makes it suitable to replace completely the forage in the fattening diets of sheep, being preferable to use leaves harvested in spring and winter.

Effect of Sulfur Content on Microbial Composition and Biodegradation of a Brazilian Diesel and Biodiesel Blend (B10)

Environmental legislation has driven the reduction of sulfur levels in automotive fuels worldwide (≤10 ppm). We evaluate the behavior of microbial biomass in terms of community composition, metabolite production, and degradation of the Brazilian blend B10, made with ultra-low-sulfur diesel (ULSD, 6.3 ppm), high-sulfur diesel (HSD, 327 ppm), and ultra-high-sulfur diesel (UHSD, 861 ppm) during simulated storage. The microcosm was assembled in glass flasks containing an aqueous phase (mineral medium) and an oil phase (fuels) at two conditions of microbial contamination: natural (∼103 colony-forming units (CFU) per liter ) and inoculated (∼106 bacterial cells and fungal spores per milliliter), evaluated each 10 days for 40 days. The results showed that biomass production was more pronounced in inoculated treatment and could be described at T40 as UHSD < ULSD < HSD B10. The higher degradation of terminal methyl ester fraction (50 ± 1%), and aromatic compounds (46 ± 2%) was in HSD B10, and ULSD B10 suffered the...

In situ and in vitro evaluation of crude protein degradation and utilisable crude protein content of barley, rye and triticale grains for ruminants.

Rations for dairy cows are comprised of high proportions of cereal grains. Thus, despite their low crude protein (CP) content, grains can contribute considerably to the CP intake of dairy cows. This study was conducted to describe and compare ruminal CP degradation of a broad range of barley, rye and triticale genotypes in situ and in vitro and different methods to estimate the utilisable CP at the duodenum (uCP). Twenty samples each of rye, barley and triticale were incubated in situ and in vitro. Exponential regression analyses were used to estimate in situ degradation parameters. Further, the effective degradability (ED), ruminal undegraded CP (UDP) and uCP for ruminal passage rates of 5% and 8% per hr were estimated. The uCP was estimated in vitro and based on two different approaches using in situ UDP data and estimates of microbial synthesised protein (based on fermented organic matter [fOM] or equations of the Gesellschaft für Ernährungsphysiologie). The degradation rate declined from rye (43% per hr) to triticale (27% per hr) to barley (20% per hr), and it exhibited remarkable variation between the genotypes of a single species. The maximal degradable CP fraction also differed between the species, but was overall very high (94%-99%). The lowest washout fraction (26%) and the highest variation in ED (77%-86% and 69%-80% for a passage rate of 5% and 8% per hr, respectively) were found in barley. The in situ uCP content (estimated using fOM) was lower for barley than for rye and triticale at ruminal passage rates of 5% and 8% per hr (barley: 157g/kg DM at both passage rates; rye and triticale: 168 (at 5% per hr) and 169 (at 8% per hr) g/kg DM). In vitro estimations of uCP did not differ between the grain species and uCP estimated according to GfE was higher for triticale than for barley and rye, which did not differ. The low variation within a single grain species and the weak correlations between ruminal CP degradation and nutrient concentrations suggested that differentiation of ED and uCP between the genotypes of a single grain species is not necessary.

Investigation of conditions for dilute acid pretreatment for improving xylose solubilization and glucose production by supercritical water hydrolysis from Quercus mongolica

Abstract The objective of this study was to prepare a feedstock, which xylose should be highly solubilized and most of the glucose remained in the solid fraction, for supercritical water hydrolysis (SCWH). Response surface methodology (RSM) with two independent variables (reaction time and sulfuric acid concentration) was adopted to find suitable conditions for pretreatment using a simple apparatus an autoclave for massive production. Based on the results of the RSM experiments, higher xylose contents were obtained in the liquid fraction after dilute acid pretreatment at 121 °C for 60 min with 6.82% H2SO4 (condition #8 (18.0%)) and at 121 °C for 102.3 min with 4% H2SO4 (condition #6 (16.0%)). To preventing corrosion of the apparatus, condition #6 was modified by prolonging the reaction time to 105 min, which led to a xylose content of 17.6% in the liquid fraction. Furthermore, structural degradation of the solid fraction was observed, indicating a positive effect for sugar production via SCWH.

Does microbial nitrogen contamination affect the estimation of crude protein degradability of concentrate feeds?1

The effects of microbial contamination (MC) on CP degradability of concentrate feeds are still controversial. Therefore, the aim of this study was to use 15N to estimate the impact of MC on estimations of CP fractions (the soluble fraction of CP [a], the insoluble but potentially degradable fraction of CP [b], and the rate of digestion of fraction b [kd]) of concentrate feeds. Twelve types of feed were evaluated: 6 energy concentrates—wheat bran (Triticum aestivum L.), rice meal (Oryza sativa L.), ground corn (Zea mays L.), ground sorghum (Sorghum vulgare Pers.), ground corn cob (Zea mays L.), and soybean hulls [Glycine max (L.) Merr.]—and 6 protein concentrates—cottonseed meal (Gossypium hirsutum L.), soybean meal [Glycine max (L.) Merr.], ground bean (Phaseolus vulgaris L.), peanut meal (Arachis hypogaea L.), sunflower meal (Helianthus annuus L.), and corn gluten meal (Zea mays L.). The feeds were divided into 4 groups and were incubated in the rumen of 4 crossbred bulls. The samples were incubated for 0, 2, 4, 8, 16, 24, 48, and 72 h. To estimate the MC of the incubated residues, the ruminal bacteria were labeled with 15N via continuous intraruminal infusion of 15(NH4)2SO4. There was no difference (P = 0.738) between corrected and uncorrected parameters a, b, and kd for all feeds that were evaluated. All of the feed tests followed an exponential model of degradation, and the model fitted well to the data, except for corn gluten meal, probably because the maximum incubation time that was used (72 h) was not long enough to allow for an accurate estimation of the degradation profile. Therefore, correction of ruminal protein degradation to MC is irrelevant with regards to the concentrates that were studied.

Determination of protein degradability of alfalfa hay via buffer or protease

This study was conducted to determine the effect of different vegetative periods on protein fractions of alfalfa hay and to compare two different methods for estimation of its protein degradability. In this study, 44 alfalfa hay samples cut in late vegetative, late bud, early bloom and late bloom were used. Crude protein decreased with advancing maturity (p < .05), but neutral detergent insoluble nitrogen and acid detergent insoluble nitrogen were similar. Protein degradability of the samples was estimated using Streptomyces griseus protease or borate–phosphate buffer, kinetic model, as described in Cornell Net Carbohydrate Protein System (CNCPS). Alfalfa hay samples were subjected to proteolysis for 30 h with 0.115 U/mL or 0.230 U/mL of the protease at pH 6.8. There was a moderate correlation (0.66, 0.72) between enzymatic and buffer method estimates with protein degradation. As vegetation progresses, rapidly degradable fraction (A) decreased (p < .05) and undegradable fraction (C) increased (p < .05), while potentially degradable fraction (B) was unchanged. Rumen degradable protein content decreased (p < .05) with advancing maturity. The enzyme/duration limits should be standardised and investigated whether the protease enzyme alone is sufficient for all forages.

608 Replacing corn grain by crude glycerol in diets of grazing dairy cows: Feed intake, pasture degradability, and milk production

Eighteen Holstein cows (6 ruminally cannulated) were used in the first 60 days of lactation to evaluate the effect of the replacement of corn grain (CG) by crude glycerol (CGly) on organic matter intake (OMI), pasture degradability and milk yield (MY). Cows were blocked [by parity (3.17±1.42), body condition score (3.0±0.3), expected caving date], and assigned randomly to two treatments (T). T1= partially mixed diet (PMR) containing sorghum silage (SS) plus concentrate (CG, wheat grain, soybean expeller, minerals and vitamins) and T2= PMR containing SS plus concentrate where CGly -76.5% glycerol, ALUR Uruguay- replacing the CG. Both groups received PMR in individual feeders and grazed during afternoon in a temperate pasture with herbage allowance-above the ground level- 60 kg DM.cow-1.day-1. Chemical composition of PMR (OM, CP, NDF, and EE in g/kgDM) respectively was for T1 [934, 117, 317, and 5] and [927, 106, 297 and 46] for T2. OMI and the ruminal degradation kinetics of DM of pasture were measured in situ in two periods. PMR intake (OMI-PMR) was measured individually as the difference between the amounts offered and refused. OMI-forage was determined with chromium oxide (Cr2O3) and indigestible acid detergent fiber as external and internal marker respectively. In situ data was fitted to nonlinear model D(t)=a+b(1-e-ct), where D= disappearance of DM , (a) soluble fraction, (b) degradable fraction, and (c) degradation rate. MY was Individual measured daily. Intake, degradability parameters, and MY were analyzed with a mixed model whit repeated measures. The model included fixed effects: T, period/week, interaction T*period and cow as a random effect. The statistical analyzes were performed with SAS (2010), data are expressed as lsmeans (s.e) and were considered to differ when P < 0.05. Treatment or interaction did not affect Total organic matter intake, OMI-PMR or OMI-f and was [23.6(1.4), 12.7(0.5) and 10.9 (1.0)] kgOM.d-1 for T1 and [20.8(1.3), 10.9(0.5) and 9.8 (0.9)] kg OM.d-1 for T2 respectively. The parameters “a”, “b” “c” of pasture were not affected by T, period or interactions and averaged 20(3.1) g/kgDM 602 (3.6) g/kgDM, 0.04(0.007) h-1. Milk yields was not affected by treatment (30.6(1.0) kg.día-1) or interaction T*week of lactation (WOL) but as expected it was affected for WOL. The absence of negative effects related to the use of CGly in substitution of CG in these conditions allows its use up to 10% DMI for dairy cows without altering the efficiency of the milk production process.

577 In vitro ruminal fermentation and enteric methane production of tropical forages supplemented with nitrogen or the combination of nitrogen and starch

This research was conducted to evaluate in vitro ruminal fermentation parameters (CO2emissions, NDF degradability, pH, VFA, and NH3-N) and enteric methane production of medium quality tropical grass hay (TGH;Brachiaria decumbens, 6.8% CP), supplemented with N only (urea:ammonium sulfate), or the combination of N and starch. The 7 treatments evaluated were: control (TGH only, 6.8% CP), N supplementation (TGH + N at 90.1 and TGH + N 130 g/kg), N + starch supplementation (low starch, 10% of forage weight; and high starch, 20% of forage weight). Samples were incubated in serum bottles (50 mL) at 39C, each run being replicated 4 times. Methane, CO2, and VFA were evaluated after 24-h incubation. The measurements of NDF degradability, NH3-N concentration, and pH were performed at 3, 6, 9, 12, 24, 36, 48, 72 and 96 h. Values of pH, NH3-N, VFA, CH4, and CO2obtained for the different incubation times were evaluated as repeated measures design. Data were analyzed using PROC MIXED of SAS (SAS Inst., Cary, NC) and differences were declared significant atPï‚£0.05. Treatment was considered fixed effect whereas treatment within run considered random. When expressed in mL/g DM, no effect was found on CH4(P =0.498) and CO2(P =0.538) production, potentially degradable fraction of NDF (P =0.429), nondegradable fraction of NDF (P =0.429), and fractional degradation rate of NDF (P =0.568). Yet, compared to control, supplementation did affect total VFA concentration (P < 0.05), more specifically, with starch affecting (P < 0.05) total acetate production, and decreasing A:P ratio (P < 0.05). The pH was found to be higher for supplemented diets (P < 0.05). Supplementation also affected NH3-N, after 36 h, with high starch inclusion being the highest (P < 0.05). Overall, the N supplementation alone does not improve TGH fermentation dynamics, and independent of the level of N supplementation, the inclusion of starch onto TGH supplementation strategies is likely to affect only VFA profile rather than total production.