Effects of exogenous amylase on the in vitro digestion kinetics of whole-crop maize silages made from flint or dent grain type at different phenological stages grown in tropical condition

The effect of exogenous amylase on the in vitro rumen digestion kinetics of whole-crop maize silage made from dent (RB9004) or flint grain type (RB9308) was evaluated at different phenological stages: soft dough (SOD), early dent (EAD), ½ milkline (½M) and ¾ milkline (¾M). Forage was harvested from 70 to 110 days after sowing. Two rumen-cannulated cows receiving or not exogenous amylase (0.7 g/kg dry matter—DM, provided to achieve 396 kilo Novo units of amylase activity/kg of TMR DM) were used as donor of ruminal fluid. The in vitro gas production kinetics was evaluated according to a dual-pool logistic model. The chemical composition and gas production kinetics were affected by the hybrid and phenological stages. The flint hybrid had lower range for chemical analysis among physiological stages. Harvesting at ½M and ¾M improved DM content, bromatological composition and silage quality parameters compared to dent or flint types. Amylase (i) increased methane (CH₄) production and in vitro dry matter digestibility (IVDMD) in ½M stage, (ii) improved digestion kinetics by reducing lag time and increasing total gas production and fermentation rates of non-fibrous carbohydrates (NFC) and fibrous carbohydrates (FC), and (iii) increased extent and fermentation rate of NFC and increased fermentation rate of FC fraction in whole-crop maize silages produced from dent or flint types in all phenological stages. Harvesting between ½M and ¾M is the best phenological stage to improve chemical composition and silage quality parameters. Exogenous amylase showed improvements on fibre digestion of silages at ½M and ¾M phenological stages in both grain types of corn.     

DETERMINATION OF OLIVE MILL WASTEWATER TOXIC EFFECTS ON THREE MINT SPECIES GROWN IN HYDROPONIC CULTURE

The effects of two olive mill wastewater (OMW) dilutions upon physiological function and metabolic components of three mint species grown in hydroponic culture were studied. Visible symptoms, chlorosis and stunted growth, were pronounced in peppermint and spearmint; toxicity symptoms in menthe douce were few. Peppermint and spearmint displayed loss of calcium (Ca), magnesium (Mg), and potassium (K); menthe douce revealed accumulation of Ca, sodium (Na), and iron (Fe), under OMW. The loss of Ca negatively affected the development and stability of cell wall and membrane; the Mg deficiency negatively affected the photosynthetic apparatus and carbon fixation. Fv′/ Fm′ was slightly affected under OMW, whereas, Φ_PSII, q _P and Rfd displayed significant reductions. No clear effect of OMW on phenols and carbohydrates among the species were found. Ascorbic acid content in peppermint dropped dramatically; the reduction was lower for spearmint and menthe douce. The OMW resistant species, menthe douce, developed a mechanism to control the physiological and the biochemical status.     

Biochemical factors in wheat (Triticum aestivum L.) involved in the tetany syndrome

Nitrogen in winter wheat (Triticum aestivum L.) forage was fractionated into water‐soluble protein N (WSPN) and non‐protein N (NPN). Both WSPN and NPN can be rapidly converted to ammonia in the rumen which may increase pH of rumen fluid and decrease solubility of Mg compounds and lead to increased incidence of grass tetany. In plant samples taken after spring growth initiation, WSPN represented approximately 50% of total N and NPN represented approximately 25% of total N. Total N concentration and relative percentages of WSPN and NPN decreased with advancing plant maturity in 1974, but during 1975 the relative WSPN and NPN percentages remained relatively constant at 43 to 55% and 18 to 30% of total N, respectively. Total N, WSPN, and NPN concentrations decreased as plants matured.

Total water‐soluble carbohydrates (TWSC) were determined and N/TWSC ratios were calculated in wheat forage. TWSC concentrations increased from the initial sampling date to a peak concentration and then declined during the latter part of the sampling period. N/TWSC ratios were widest at the initial sampling date and decreased markedly in subsequent samplings.

Organic acid concentrations were determined in 1975 wheat forage samples by gas‐liquid chromatography. Citric and trans‐aconitic acids have been implicated in the etiology of grass tetany as chelating agents for Mg and Ca. Chelation in the rumen fluid may reduce Mg and Ca absorption or chelation in the blood serum may reduce biological activity. Malic and aconitic acids accumulated in wheat. Malic acid concentration increased with advancing plant maturity to a maximum of 1.70% (dry weight basis). Aconitic acid concentrations were highest at the mid‐point in the sampling period, a maximum of 1.24% being determined.     

EFFECT OF PREVIOUS NITROGEN STARVATION ON NO3 − AND NH4 + UPTAKE AND ASSIMILATION ASSOCIATED WITH THE ENDOGENOUS SOLUBLE CARBOHYDRATE UTILIZATION IN MOROCCAN WHEAT SEEDLINGS

Uptake of the two forms of nitrogen NO₃ ^? and NH₄ ⁺ and nitrate reduction have been studied in two varieties of Moroccan wheat seedlings, cvs. Sais and Jouda, cultivated under controlled conditions in a hydroponic medium. The available form of nitrogen in the medium had a direct effect on the rate of nitrogen absorption. A brief nitrogen starvation increased the root length and stimulated accumulation of soluble carbohydrates, especially in the root tissues. A resupply of nitrogen stimulated ammonium and nitrate uptake and assimilation with higher mobilization of the soluble carbohydrates previously accumulated in root seedlings. It is suggested that root nitrogen and carbohydrate status might both regulate nitrate uptake and reduction in Moroccan wheat seedlings.

The seedlings raised with the nitrate supply accumulated nitrate in the vacuole as an osmoticum. Shoots are the preferential site for such accumulation. The accumulation of mineral nitrogen was absent in the seedlings cultivated with ammonium supply but was compensated by accumulation of soluble organic nitrogen.     

Limited genotype- and ploidy-related variation in the nutritive value of perennial ryegrass (Lolium perenne L.)

Abstract

Water-soluble carbohydrates and fibre fractions are important traits that influence forage utilization by the ruminant. Little is known about the quality variation among perennial ryegrass genotypes within the same maturity group or between near-isogenic diploids and tetraploids. The current study was carried out in the form of two experiments on two successive years (2006–2007) in three sites in Northern Germany. The main aim was to investigate the variation in nutritive value that could be attributed to differences in maturity among 20 intermediate heading perennial ryegrass genotypes or to differences in ploidy between near-isogenic diploids and tetraploids. Results of the first experiment revealed significant variation among the 20 tested genotypes in the investigated quality parameters that were consistent with the discovered variation in the maturity of the genotypes determined in terms of their Mean Stage by Count (MSC). In the second experiment, few but consistent significant differences were detected between near-isogenic diploids and tetraploids. The tetraploid derivatives had always significantly higher water-soluble carbohydrate content and lower neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) than their near-isogenic diploid parents.     

Buckwheat Seed Milling Fractions: Description, Macronutrient Composition and Dietary Fibre

The structure of the mature buckwheat achene and groat is discussed in relation to milling fractions and nutritional composition. Whole groats contain 55% starch, 12% protein, 4% lipid, 2% soluble carbohydrates, 7% total dietary fiber (TDF), 2% ash, and 18% other components (organic acids, phenolic compounds, tannins, phosphorylated sugars, nucleotides and nucleic acids, unknown compounds). The composition of the milling fractions reflects the relative abundance of seed tissues. Starch is concentrated in the central endosperm. Protein, oil, soluble carbohydrates and minerals are concentrated in the embryo. Commercial «Fancy» flour, a light-coloured flour, is mostly central endosperm and contains 75% starch, 6% protein, 1% lipid, 1% soluble carbohydrates, 3% TDF, 1% ash, and 13% other components. Although the embryo traverses the central endosperm, during milling parts of the embryo separate with the aleurone and seed coat in the bran fraction. Bran, with little central endosperm, contains 18% starch, 36% protein, 11% lipid, 6% soluble carbohydrates, 15% TDF, 7% ash, and 7% other components. Buckwheat bran also is a rich source of TDF and soluble dietary fibre (SDF), particularly bran with hull fragments (40% TDF of which 25% is SDF), while bran without hull fragments has 16% TDF of which 75% is SDF.     

Protein degradation and fermentation characteristics of unwilted red clover and alfalfa silage harvested at various times during the day

Extensive proteolysis during fermentation of high‐protein legumes reduces dietary N‐use efficiency in ruminants. Research has demonstrated that enhancing the level of fermentable carbohydrates in crops entering the silo may reduce protein degradation by increasing the rate of decline in pH. The objective was to evaluate whether delaying cutting time during the day, to allow accumulation of total non‐structural carbohydrates (TNC), would inhibit proteolysis in the silo. Red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) were harvested at 06.00, 10.00, 14.00 and 18.00 hours in 1993, 1994 and 1995, and ensiled without wilting. TNC accumulated in fresh forage during the day, with starch accounting for more than 0·50 of the daily change in TNC in fresh herbage of both species, except in red clover in 1995. The level of TNC in fresh forage did not consistently affect the extent of protein degradation in either species and, in all instances, alfalfa underwent more extensive proteolysis than red clover. Silage pH typically decreased and starch concentration increased as cutting time was delayed from 06.00 to 18.00 hours. Although the extent of proteolysis was largely unaffected by inherent increases in TNC, harvesting in the afternoon did provide several benefits including increased dry‐matter content, lower silage pH and higher starch concentrations. Effluent production is a concern in any unwilted silage system; there was therefore an added advantage of lower moisture content from cutting in the afternoon.     

球磨法合成钒基催化剂及其催化生物质制备甲酸

分别采用无溶剂机械球磨法和浸渍法合成了V/ZSM-5固体催化剂,通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱分析(XPS)、N2物理吸附和电感耦合等离子体质谱(ICP-MS)等手段表征了催化剂的物相、表面形貌、V的价态、比表面积以及V的含量。结果表明,两种方法合成的催化剂中V元素的负载量接近(约为1.7%)。相比于传统浸渍法,本研究提出的球磨法无需任何溶剂,时间短(1 h),其合成的催化剂颗粒较小,比表面积更大(367.0 m^2·g^-1 vs 223.9 m^2·g^-1),且球磨法得到的催化剂V的价态较高,相同催化条件下球磨法合成的催化剂性能优于浸渍法合成的催化剂(45%vs 35%)。系统研究了不同实验因素对催化反应的影响规律,在温度180℃、水为溶剂、催化剂与底物质量比为1∶2、氧气3 MPa、反应时间30 min时,葡萄糖转化产甲酸的产率最高,达到45%。此外,在该球磨法合成的催化剂作用下,多种生物质基碳水化合物均能用来制备甲酸。本研究为金属负载型催化剂的设计合成提供了另一种途径,简单、高效、易操作且环境友好,对于木质纤维素类农林废弃物向高附加值化学品的转化具有重要意义。     

Interaction between water-soluble carbohydrate reserves and defoliation severity on the regrowth of perennial ryegrass (Lolium perenne L.)-dominant swards

A field-study was undertaken in Hamilton, New Zealand to determine if there was an interaction between water-soluble carbohydrate (WSC) reserve content and defoliation severity on the regrowth of perennial ryegrass-dominant swards during winter. Perennial ryegrass plants with either low or high WSC content were obtained by varying the defoliation frequency. At the third defoliation at the one-leaf stage and at the first defoliation at the three-leaf stage (harvest H₁), swards were mown with a rotary lawnmower to residual stubble heights of 20, 40 or 60 mm. All swards were then allowed to regrow to the three-leaf stage before again defoliating to their treatment residual stubble heights (H₂). Frequently defoliated plants contained proportionately between 0·37 and 0·48 less WSC in the stubble after defoliation, depending on the severity of defoliation. There was no interaction between WSC content and defoliation severity for herbage regrowth between harvests H₁ and H₂. Herbage regrowth was lower from swards containing low WSC plants compared with high WSC plants (2279 vs. 2007 kg DM ha⁻¹). Furthermore, swards defoliated to 20 or 40 mm had greater herbage regrowth compared with those defoliated to 60 mm (2266, 2249 and 1914 kg DM ha⁻¹ for swards defoliated to residual stubble heights of 20, 40 and 60 mm, respectively). Regrowth of perennial ryegrass was positively correlated with post-defoliation stubble WSC content within defoliation severity treatment, implying that WSC contributed to the defoliation frequency-derived difference in herbage yield. However, the effect of defoliation severity on herbage regrowth was not associated with post-defoliation stubble WSC content.