Influence of phytase and xylanase supplementation on growth performance and nutrient utilisation of broilers offered wheat-based diets

Individual and combined supplementation of phosphorus-adequate, wheat-based broiler diets with exogenous phytase and xylanase was evaluated in three experiments. The effects of the enzyme combination in lysine-deficient diets containing wheat and sorghum were more pronounced than those of the individual feed enzymes. The inclusion of phytase plus xylanase improved (p<0.05) weight gains (7.3%) and feed efficiency (7.0%) of broilers (7-28 days post-hatch) and apparent metabolisable energy (AME) by 0.76 MJ/kg DM. Phytase plus xylanase increased (p<0.05) the overall, apparent ileal digestibility of amino acids by 4.5% (0.781 to 0.816); this was greater than the responses to either phytase (3.6%; 0.781 to 0.809) or xylanase (0.7%; 0.781 to 0.784). Absolute increases in amino acid digestibility with the combination exceeded the sum of the individual increases generated by phytase and xylanase for alanine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, phenylalanine, threonine, tyrosine and valine. These synergistic responses may have resulted from phytase and xylanase having complementary modes of action for enhancing amino acid digestibilities and/or facilitating substrate access. The two remaining experiments were almost identical except wheat used in Experiment 2 had a higher phytate concentration and a lower estimated AME content than wheat used in Experiment 3. Individually, phytase and xylanase were generally more effective in Experiment 2, which probably reflects the higher dietary substrate levels present. Phytase plus xylanase increased (p<0.05) gains (15.4%) and feed efficiency (7.0%) of broiler chicks from 4-24 days post-hatch in Experiment 2; whereas, in Experiment 3, the combination increased (p<0.05) growth to a lesser extent (5.6%) and had no effect on feed efficiency. This difference in performance responses appeared to be 'protein driven' as the combination increased (p<0.05) nitrogen retention in Experiment 2 but not in Experiment 3; whereas phytase plus xylanase significantly increased AME in both experiments. In Experiments 2 and 3 the combined inclusion levels of phytase and xylanase were lower that the individual additions, which demonstrates the benefits of simultaneously including phytase and xylanase in wheat-based poultry diets.

The cell wall galactans from Australian representatives of the genus Meristotheca (solieriaceae, rhodophyta)

The Solieriaceae, has the largest number of genera (16-18) of any family in the carrageenophyte order Gigartinales. One of these genera, Meristotheca, consists of three or four species of foliose, erect to prostrate plants sporadically recorded from the tropics of both hemispheres. The hot-water-soluble polysaccharides from Australian representatives of the type species, M. papulosa, and M. procumbens from Lord Howe Island have been characterized by compositional assays, linkage analysis, and Fourier transform infrared and C-13-nuclear magnetic resonance spectroscopy. The results show that polysaccharides from both species are similar, being predominantly composed of 4-linked 3,6-anhydro-alpha-D-galactopyranose 2-sulphate alternating with 3-linked beta-D-galactopyranose 4-sulphate, as is typical of iota-carrageenan. Small proportions of the 3-linked units occur as the pyruvated residue 4,6-O-(1-carboxyethylidene)-beta-D-galactopyranose, and other minor variations from idealized iota-carrageenan were also detected. The polysaccharides from representatives of Meristotheca are comparable to those of other solieriacean algae analysed to date, but the minor structural variations suggest a closer chemotaxonomic affinity with noneucheumoid genera of the Solieriaceae, such as Sarconema, Solieria, and Tikvahiella, than to the eucheumoid genera Eucheuma, Kappaphycus and Betaphycus (tribe Eucheumatoideae) from which most kappa- and iota-carrageenans are commercially extracted.

Permeability studies of alkylamides and caffeic acid conjugates from echinacea using a Caco-2 cell monolayer model

Background: Echinacea is composed of three major groups of compounds that are thought to be responsible for stimulation of the immune system-the caffeic acid conjugates, alkylamides and polysaccharides. This study has focussed on the former two classes, as these are the constituents found in ethanolic liquid extracts. Objective: To investigate the absorption of these two groups of compounds using Caco-2 monolayers, which are a model of the intestinal epithelial barrier. Results: The caffeic acid conjugates (caftaric acid, echinacoside and cichoric acid) permeated poorly through the Caco-2 monolayers although one potential metabolite, cinnamic acid, diffused readily with an apparent permeability (P-app) of 1x10(-4) cm/s. Alkylamides were found to diffuse through Caco-2 monolayers with P-app ranging from 3x10(-6) to 3x10(-4) cm/s. This diversity in P-app for the different alkylamides correlates to structural variations, with saturation and N-terminal methylation contributing to decreases in P-app. The transport of the alkylamides is not affected by the presence of other constituents and the results for synthetic alkylamides were in line with those for the alkylamides in the echinacea preparation. Conclusion: Alkylamides but not caffeic acid conjugates are likely to cross the intestinal barrier.

Despite differences between dendritic cells and Langerhans cells in the mechanism of papillomavirus-like particle antigen uptake, both cells cross-prime T cells

As human papillomavirus-like particles (HPV-VLP) represent a promising vaccine delivery vehicle, delineation of the interaction of VLP with professional APC should improve vaccine development. Differences in the capacity of VLP to signal dendritic cells (DC) and Langerhans cells (LC) have been demonstrated, and evidence has been presented for both clathrin-coated pits and proteoglycans (PG) in the uptake pathway of VLP into epithelial cells. Therefore, we compared HPV-VLP uptake mechanisms in human monocyte-derived DC and LC, and their ability to cross-present HPV VLP-associated antigen in the MHC class I pathway. DC and LC each took up virus-like particles (VLP). DC uptake of and signalling by VLP was inhibited by amiloride or cytochalasin D (CCD), but not by filipin treatment, and was blocked by several sulfated and non-sulfated polysaccharides and anti-CD16. In contrast, LC uptake was inhibited only by filipin, and VLP in LC were associated with caveolin, langerin, and CD1a. These data suggest fundamentally different routes of VLP uptake by DC and LC. Despite these differences, VLP taken up by DC and LC were each able to prime naive CD8(+) T cells and induce cytolytic effector T cells in vitro. (C) 2004 Elsevier Inc. All rights reserved.

A nearly idealized 6 '-O-methylated t-carrageenan from the Australian red alga Claviclonium ovatum (Acrotylaceae, Gigartinales)

The polysaccharides extracted from Claviclonium ovatum were studied by a combination of compositional assays, reductive partial hydrolysis, linkage analysis, Fourier Transform infrared (FTIR) spectroscopy, and C-13, H-1, and C-13/H-1 heteronuclear multiple quantum correlation (HMQC) two-dimensional nuclear magnetic resonance (NMR) spectroscopy. The chemical and spectroscopic data showed that the alkali-modified C. ovatum polysaccharides are composed of a nearly idealized repeating unit of 6'-O-methylcarrabiose 2,4'-disulfate (the repeating unit of 6-O-methylated iota-earrageenan), although some minor components were also present. The C. ovatum galactans are the most highly methylated carrageenans reported. (C) 2004 Elsevier Ltd. All rights reserved.

The seeds of lotus japonicus lines transformed with sense, antisense, and sense/antisense galactomannan galactosyltransferase constructs have structually altered galactomannan in their endosperm cell walls

Galactomannan biosynthesis in legume seed endosperms involves two Golgi membrane-bound glycosyltransferases, mannan synthase and galactomannan galactosyltransferase (GMGT). GMGT specificity is an important factor regulating the distribution and amount of (1-->6)-alpha-galactose (Gal) substitution of the (1-->4)-beta-linked mannan backbone. The model legume Lotus japonicus is shown now to have endospermic seeds with endosperm cell walls that contain a high-Gal galactomannan (mannose [Man]/Gal = 1.2-1.3). Galactomannan biosynthesis in developing L. japonicus endosperms has been mapped, and a cDNA encoding a functional GMGT has been obtained from L. japonicus endosperms during galactomannan deposition. L. japonicus has been transformed with sense, antisense, and sense/antisense ("hairpin loop") constructs of the GMGT cDNA. Some of the sense, antisense, and sense/antisense transgenic lines exhibited galactomannans with altered (higher) Man/Gal values in their (T-1 generation) seeds, at frequencies that were consistent with posttranscriptional silencing of GMGT. For T-1 generation individuals, transgene inheritance was correlated with galactomannan composition and amount in the endosperm. All the azygous individuals had unchanged galactomannans, whereas those that had inherited a GMGT transgene exhibited a range of Man/Gal values, up to about 6 in some lines. For Man/Gal values up to 4, the results were consistent with lowered Gal substitution of a constant amount of mannan backbone. Further lowering of Gal substitution was accompanied by a slight decrease in the amount of mannan backbone. Microsomal membranes prepared from the developing T-2 generation endosperms of transgenic lines showed reduced GMGT activity relative to mannan synthase. The results demonstrate structural modification of a plant cell wall polysaccharide by designed regulation of a Golgi-bound glycosyltransferase.

Inhibition of cell-wall autolysis and pectin degradation by cations

Modification of cell wall components such as cellulose, hemicellulose and pectin plays an important role in cell expansion. Cell expansion is known to be diminished by cations but it is unknown if this results from cations reacting with pectin or other cell wall components. Autolysis of cell wall material purified from bean root (Phaseolus vulgaris L.) occurred optimally at pH 5.0 and released mainly neutral sugars but very little uronic acid. Autolytic release of neutral sugars and uronic acid was decreased when cell wall material was loaded with Ca, Cu, Sr, Zn, Al or La cations. Results were also extended to a metal-pectate model system, which behaved similarly to cell walls and these cations also inhibited the enzymatic degradation by added polygalacturonase (EC 3.2.1.15). The extent of sugar release from cation-loaded cell wall material and pectate gels was related to the degree of cation saturation of the substrate, but not to the type of cation. The binding strength of the cations was assessed by their influence on the buffer capacity of the cell wall and pectate. The strongly bound cations (Cu, Al or La) resulted in higher cation saturation of the substrate and decreased enzymatic degradability than the weakly held cations (Ca, Sr and Zn). The results indicate that the junction zones between pectin molecules can peel open with weakly held cations, allowing polygalacturonase to cleave the hairy region of pectin, while strongly bound cations or high concentrations of cations force the junction zone closed, minimising enzymatic attack on the pectin backbone. (C) 2004 Elsevier SAS. All rights reserved.

Glass transition and enthalpy relaxation of amorphous food saccharides: A review

Many food materials exist in a disordered amorphous solid state due to processing. Therefore, understanding the concept of amorphous state, its important phase transition (i.e., glass transition), and the related phenomena (e.g., enthalpy relaxation) is important to food scientists. Food saccharides, including mono-, di-, oligo-, and polysaccharides, are among the most important major components in food. Focusing on the food saccharides, this review covers important topics related to amorphous solids, including the concept and molecular arrangement of amorphous solid, the formation of amorphous food saccharides, the concept of glass transition and enthalpy relaxation, physical property changes and molecular mobility around the glass transition, measurement of the glass transition and enthalpy relaxation, their mathematical descriptions and models, and influences on food stability.

Palm kernel meal in broiler diets: effect on chicken performance and health

An increase in the production of palm kernel meal (PKM) coupled with the concern for continued availability of conventional feedstuffs in some parts of the world has led to research to establish the maximum inclusion level of palm kernel meal in broiler diets. The results suggested that palm kernel meal has no anti-nutritional properties and thus its inclusion is safe up to at least 40% in the diet, provided the diet is balanced in amino acids and metabolisable energy. Although feed digestibility is decreased due to high dietary fibre when PKM is included in the diet, the feed intake is increased. This makes total digestible nutrient intake relatively high. beta-mannan is the main component of palm kernel meal non-starch polysaccharide (NSP). Both mannose and manno-oligosaccharides have been reported to act as prebiotics. The inclusion of palm kernel meal in the diet improves the immune system of birds and reduces pathogenic bacteria and increases the population of nonpathogenic bacteria in the intestine. These two benefits should be considered as strong recommendations for using palm kernel meal in broiler diets, particularly in palm kernel meal producing countries, not only for increasing bird productivity but also to improve chicken health. Selective enzyme addition increases feed efficiency and digestibility as well as decreasing the moisture content of faeces.

Screening, characterization and flocculating property of carbohydrate polymer from newly isolated Enterobacter cloacae WD7

A total of 188 carbohydrate polymer-producing bacterial strains were isolated from recycled sludge of five seafood processing plants. Among three selected isolates, identified as Enterobacter cloacae WD7, Enterobacter agglomerans WD50 and Pseudomonas alcaligenes WD22. E. cloacae WD7 generated a viscous culture broth exhibiting the highest flocculating activity and a crude polymer yield of 2.27 g/L after 3 days cultivation. Partial purification of this polymer was performed by precipitation with 95% ethanol, dialysis and freeze-drying. It was characterized as an acidic heteropolysaccharide, composed of neutral sugars (29.4%), uronic acids (14.2%) and amino sugars (0.93%). The functional group analysis by FT-IR spectroscopy showed the presence of hydroxyl, carboxyl, carbonyl and methoxyl groups. Thermal analysis by DSC showed the crystalline transition and the crystalline melting point (T-m) at 300 degrees C. This polysaccharide was soluble in water and insoluble in any organic solvents tested; gelation occurred under alkaline conditions in the presence of divalent cations in which copper as CuSO4 gave the best result. Studies on the flocculation property revealed that this polysaccharide was stable at 4-60 degrees C and pH 5-7. The optimal concentrations for the flocculating activity were 2 mg/L polysaccharide and 40 mM CaCl2 which played the synergistic effect on kaolin flocculation. Moreover, this polysaccharide could flocculate the kaolin suspension over a wide range of pH (pH 2-8) and temperature (4-50 degrees C) tested in the presence of CaCl2. (c) 2006 Elsevier Ltd. All rights reserved.

A blank slate? Layer-by-layer deposition of hyaluronic acid and chitosan onto various surfaces

Although poly(alpha-hydroxy esters), especially the PLGA family of lactic acid/glycolic acid copolymers, have many properties which make them promising materials for tissue engineering, the inherent chemistry of surfaces made from these particular polymers is problematic. In vivo, they promote a strong foreign-body response as a result of nonspecific adsorption and denaturation of serum proteins, which generally results in the formation of a nonfunctional fibrous capsule. Surface modification post-production of the scaffolds is an often-utilized approach to solving this problem, conceptually allowing the formation of a scaffold with mechanical properties defined by the bulk material and molecular-level interactions defined by the modified surface properties. A promising concept is the so-called blank slate: essentially a surface that is rendered resistant to nonspecific protein adsorption but can be readily activated to covalently bind bio-functional molecules such as extracellular matrix proteins, growth factors or polysaccharides. This study focuses on the use of the quartz crystal microbalance (QCM) to follow the layer-by-layer (LbL) electrostatic deposition of high molecular weight hyaluronic acid and chitosan onto PLGA surfaces rendered positively charged by aminolysis, to form a robust, protein-resistant coating. We further show that this surface may be further functionalized via the covalent attachment of collagen IV, which may then be used as a template for the self-assembly of basement membrane components from dilute Matrigel. The response of NIH-3T3 fibroblasts to these surfaces was also followed and shown to closely parallel the results observed in the QCM.