Effect of in vitro docosahexaenoic acid supplementation to marine algae-adapted and unadapted rumen inoculum on the biohydrogenation of unsaturated fatty acids in freeze-dried grass

The objective of this study was to examine the ruminal biohydrogenation of linoleic (18:2n-6) and linolenic (18:3n-3) acid during in vitro incubations with rumen inoculum from dairy cattle adapted or not to marine algae and with or without additional in vitro docosahexaenoic acid (DHA, 22:6n-3) supplementation. Treatments were incubated in 100-mL flasks containing 400 mg of freeze-dried grass, 5 mL of strained ruminal fluid, and 20 mL of phosphate buffer. Ruminal fluid was collected just before the morning feeding from 3 cows receiving a control diet (49% ryegrass silage, 39% corn silage, 1% straw, and 11% concentrate, fresh-weight basis) supplemented with marine algae for 21 d (adapted rumen fluid, aRF) or from the same cows receiving the control diet only for 14 d after marine algae supplementation was stopped (unadapted rumen fluid, uRF). In half of the incubation flasks, pure DHA (5 mg) was added as an oil-ethanol solution (100 mL). Incubations were carried out during 0, 0.5, 1, 2, 4, 6, and 24 h. After 24 h, in vitro addition of DHA resulted in greater amounts (mg/incubation) of 18:3n-3 (0.23, 0.43, 0.26, and 0.34 for aRF, aRF+DHA, uRF, and uRF+DHA), 18:2n-6 (0.14, 0.22, 0.15, and 0.20 for aRF, aRF+DHA, uRF, and uRF+DHA) and trans-11, cis-15-18:2 (0.27, 2.40, 0.06, and 2.21 for aRF, aRF+DHA, uRF, and uRF+DHA), whereas no effect of inoculum source was observed. Trans-11-18:1 accumulated after 24 h when aRF was incubated irrespective of in vitro DHA supplementation, whereas in incubations with uRF, accumulation of trans-11-18:1 only occurred when DHA was added (6.40, 4.35, 1.06, and 3.91 for aRF, aRF+DHA, uRF, and uRF+DHA). The increased amounts of trans-11-18:1 were due to the strong inhibition of the reduction to 18:0 because no 18:0 was formed when trans-11-18:1 accumulated after 24 h. The results of the current experiment shows hydrogenation of trans-11, cis-15-18:2 occurred in the absence of in vitro DHA only, whereas substantial hydrogenation of trans-11-18:1 to 18:0 only took place in incubations without DHA and with unadapted rumen inoculum, confirming the higher sensitivity of the latter process to DHA.     

Energy and nitrogen balance of dairy cattle as affected by provision of different essential amino acid profiles at the same metabolizable protein supply

Amino acid composition of metabolizable protein (MP) is important in dairy cattle diets, but effects of AA imbalances on energy and N utilization are unclear. This study determined the effect of different AA profiles within a constant supplemental MP level on whole-body energy and N partitioning in dairy cattle. Five rumen-fistulated Holstein-Friesian dairy cows (2.8 ± 0.4 lactations; 81 ± 11 d in milk; mean ± standard deviation) were randomly assigned to a 5 × 5 Latin square design in which each experimental period consisted of 5 d of continuous abomasal infusion followed by 2 d of rest. A total mixed ration consisting of 58% corn silage, 16% alfalfa hay, and 26% concentrate (dry matter basis) was formulated to meet 100 and 83% of net energy and MP requirements, respectively, and was fed at 90% of ad libitum intake by individual cow. Abomasal infusion treatments were saline (SAL) or 562 g/d of essential AA delivered in 4 profiles where individual AA content corresponded to their relative content in casein. The profiles were (1) a complete essential amino acid mixture (EAAC), (2) Ile, Leu, and Val (ILV), (3) His, Ile, Leu, Met, Phe, Trp, Val (GR1+ILV), and (4) Arg, His, Lys, Met, Phe, Thr, Trp (GR1+ALT). The experiment was conducted in climate respiration chambers to determine energy and N balance in conjunction with milk production and composition, digestibility, and plasma constituents. Compared with SAL, infusion of EAAC increased milk, protein, and lactose yield, increased energy retained as body protein, and did not affect milk N efficiency. Total N intake and urine N output was higher with all AA infusions relative to SAL. Compared with EAAC, infusions of GR1+ILV and GR1+ALT produced the same milk yield and the same yield and content of milk fat, protein, and lactose, and had similar energy and N retention. Milk N efficiency was not different between EAAC and GR1+ILV, but was lower with GR1+ALT compared with EAAC, and tended to be lower with GR1+ALT compared with GR1+ILV. Infusion of ILV tended to decrease dry matter intake compared with the other AA infusions. Milk production and composition was not different between ILV and SAL. Compared with EAAC, infusion of ILV decreased or tended to decrease milk, protein, and lactose yields and milk protein content, and increased milk fat and lactose content. Milk N efficiency decreased with ILV compared with SAL, EAAC, and GR1+ILV. Milk urea concentration was not affected by essential amino acid (EAA) infusions. Plasma urea concentration did not differ between EAAC and SAL, tended to increase with ILV and GR1+ILV over SAL, and increased with GR1+ALT compared with EAAC and SAL. In conclusion, removing Arg, Lys, and Thr or removing Ile, Leu, and Val from a complete EAA profile when the total amount of EAA infused remained constant did not impair milk production, but milk N efficiency decreased when Ile, Leu, and Val were absent. Infusion of only Ile, Leu, and Val decreased milk protein yield and content and reduced milk N efficiency compared with a complete EAA profile.     

Enzymatic degumming

The oldest enzymatic degumming process (the Lurgi EnzyMax® process) was launched in 1992. It used porcine phospholipase A₂, which has the disadvantages of limited availability and not being kosher/halal. To overcome these disadvantages, various microbial enzymes have been developed; they have different specificities and therefore offer different advantages. Phospholipase C for instance has the advantage that it leads to the formation of diacylglycerols that remain in the oil being degummed. This constitutes a significant yield improvement which also results from the formation of lysophospholipids that retain less oil than their precursors. In the laboratory, a fine dispersion of the aqueous enzyme solution in the oil can be maintained so that the phospholipase enzymes can be made to interact with non‐hydratable phosphatides (NHP) in the oil phase and catalyse their hydrolysis. On an industrial scale, dispersions coalesce before the enzymatic NHP hydrolysis is complete. Accordingly, enzymatic degumming processes that claim NHP‐removal and a low residual phosphorus content in the enzymatically degummed oil are invariably preceded by an acid treatment in which a degumming acid (citric acid) is finely dispersed into the oil to be degummed and made to react with the NHP present in the oil before the enzyme is added. This enzyme then only interacts with the phospholipids present in the water phase. This raises the question whether the yield increase resulting from the use of enzymes should be realised by treating the oil to be degummed or the gums that have already been isolated from the oil during a degumming treatment. Lack of experimental evidence prevents a firm answer to this question but the arguments in favour of treating the gums look more impressive than what can be said in favour of treating the oil. In short: Enzymes do not degum the oil but can be used to de‐oil the gums.     

Elasticity at large deformations and high strain rates in injection molded polypropylene

The deformation behavior of isotactic polypropylene (PP) as a function of strain rate was investigated at 50°C in uniaxial tension. Injection molded dogbone specimens were tested at high strain rates, ε = 10^?1 – 10² s^?1, and the local deformation in the neck was studied using fast tensile videometry. A strong elastic recoil was observed after fracture in this strain rate range with local elastic strains as high as ?_e = 2.0 – 3.2. The recoil is very fast and takes place within 1 ms. The elastic fraction of the strain at break was found to increase with the local strain rate. The elasticity further depends on strain and temperature. The elastic deformation behavior is part of the known transition from ductile cold drawing behavior to brittle fracture that occurs with strain rate or temperature. The elasticity in PP is thought to be due to a decrease in crystallinity, resulting in a discontinuous crystalline structure comparable to that of thermoplastic elastomers.     

Effect of accelerated aging of MSWI bottom ash on the leaching mechanisms of copper and molybdenum

The effect of accelerated aging of Municipal Solid Waste Incinerator (MSWI) bottom ash on the leaching of Cu and Mo was studied using a "multisurface" modeling approach, based on surface complexation to iron/aluminum (hydr)oxides, mineral dissolution/precipitation, and metal complexation by humic substances. A novel experimental method allowed us to identify that the solid/liquid partitioning of fulvic acids (FA) quantitatively explains the observed beneficial effect of accelerated aging on the leaching of Cu. Our results suggestthat iron/aluminum (hydr)oxides are the major reactive surfaces that retain fulvic acid in the bottom ash matrix, of which the aluminum (hydr)oxides were found to increase after aging. A new modeling approach, based on the surface complexation of FA on iron/aluminum (hydr)oxides is developed to describe the pH-dependent leaching of FA from MSWI bottom ash. Accelerated aging results in enhanced adsorption of FA to (neoformed) iron/aluminum (hydr)oxides, leading to a significant decrease in the leaching of FA and associated Cu. Accelerated aging was also found to reduce the leaching of Mo, which is also attributed to enhanced adsorption to (neoformed) iron/aluminum (hydr)oxides. These findings provide important new insights that may help to improve accelerated aging technology.     

Evaluation of hydrogel-coated glutamate microsensors

Glutamate microsensors form a promising analytical tool for monitoring neuronally derived glutamate directly in the brain. However, when a microsensor is implanted in brain tissue, many factors can diminish its performance. Consequently, a thorough characterization and evaluation of a microsensor is required concerning all factors that may possibly be encountered in vivo. The present report deals with the validation of a hydrogel-coated glutamate microsensor. This microsensor is constructed by coating a carbon fiber electrode (10-microm diameter; 300-500 microm long) with a five-component redox hydrogel, in which L-glutamate oxidase, horseradish peroxidase, and ascorbate oxidase are wired via poly(ethylene glycol) diglycidyl ether to an osmium-containing redox polymer. A thin Nafion coating completes the construction. Although this microsensor was previously used in vivo, information concerning its validation is limited. In the present study, attention was given to its selectivity, specificity, calibration, oxygen dependency, biofouling, operating potential dependency, and linear range. In addition, successful microsensor experiments in microdialysate, in vitro (in organotypic hippocampal slice cultures), and in vivo (in anesthesized rats) are shown.     

MEMS based hair flow-sensors as model systems for acoustic perception studies

Arrays of MEMS fabricated flow sensors inspired by the acoustic flow-sensitive hairs found on the cerci of crickets have been designed, fabricated and characterized. The hairs consist of up to 1?mm long SU-8 structures mounted on suspended membranes with normal translational and rotational degrees of freedom. Electrodes on the membrane and on the substrate form variable capacitors, allowing for capacitive read-out. Capacitance versus voltage, frequency dependence and directional sensitivity measurements have been successfully carried out on fabricated sensor arrays, showing the viability of the concept. The sensors form a model system allowing for investigations on sensory acoustics by their arrayed nature, their adaptivity via electrostatic interaction (frequency tuning and parametric amplification) and their susceptibility to noise (stochastic resonance).     

Effects of supplementing concentrates differing in carbohydrate composition in veal calf diets: I. Animal performance and rumen fermentation characteristics

The aim of this experiment was to examine the effects of concentrates in feed, differing in carbohydrate source, on the growth performance and rumen fermentation characteristics of veal calves. For this purpose, 160 Holstein Friesian × Dutch Friesian crossbred male calves were used in a complete randomized block design with a 5 × 2 factorial arrangement. Dietary treatments consisted of 1) milk replacer control, 2) pectin-based concentrate, 3) neutral detergent fiber-based concentrate, 4) starch-based concentrate, and 5) mixed concentrate (equal amounts of concentrates of treatments 2, 3, and 4). Concentrate diets were provided as pellets in addition to a commercial milk replacer. Calves were euthanized either at the end of 8 or 12 wk of age. The overall dry matter intake of the concentrate diets varied between 0.37 and 0.52 kg/d. Among the concentrate diets, the dry matter intake was lower in the starch diet (0.37 kg/d of dry matter) and differed between the NDF and pectin diets. The average daily gain for all the dietary treatments varied between 0.70 and 0.78 kg/d. The mixed- and NDF-fed calves had an increased average daily gain (0.78 and 0.77 kg/d, respectively) compared with the starch- and pectin-fed calves (0.70 and 0.71 kg/d, respectively). Rumen fermentation in the calves fed concentrates was characterized by a low pH (4.9 to 5.2), volatile fatty acid concentrations between 100 and 121 mmol/L, and high concentrations of reducing sugars (33 to 66 g/kg of dry matter). The volatile fatty acid concentrations of calves fed concentrates were higher than those of the control calves. All concentrate treatments showed a low acetate-to-propionate ratio in rumen fluid (between 1.3 and 1.9). Among the concentrates, the NDF diet had the highest (55.5%) and starch the lowest (45.5%) molar proportions of acetate. Calves fed the mixed, pectin, and starch diets had significantly higher molar proportions of butyrate (13.1 to 15.8%) than the NDF- and control-fed groups (9.9 and 9.6%, respectively). Calves fed the control diet had a higher lactate concentration (21 mmol/L) than the concentrate-fed calves (between 5 and 11 mmol/L). With the exception of the NDF diet, polysaccharide-degrading enzyme activities in the rumen contents generally showed an adaptation of the microorganisms to the carbohydrate source in the diet. The mixed diet exhibited the least variation in rumen polysaccharide-degrading enzyme activities among the enzymes systems tested. Results indicated that the carbohydrate source can influence intake, growth rate, and rumen fermentation in young veal calves.