Organic Wall Research Articles

Diversity of chemical composition, dry matter intake, in vivo digestibility and in situ dry matter degradability of oat hay (Avena sativa)

ABSTRACTDiversity of chemical composition, in vivo digestibility and in situ dry matter degradability of oat hay (Avena sativa) were studied. Oat hay samples obtained from 22 batches imported were analyzed for chemical composition. The result showed a wide range of variations in crude protein (3.9–8.8%, on a dry matter basis), crude fiber (22.1–35.2%), nitrogen free extract (50.0–66.0%), organic cellular contents (23.4–40.0%), organic cell wall (53.1–70.8%), organic a (4.1–9.8%), organic b (49.0–63.8%) fractions and the estimated total digestible nutrients (50.3–63.8%) from the organic components. Of these, four oat hay samples were used for the measurement of dry matter intake, in vivo digestibility and in situ dry matter degradability in sheep. Significant differences were observed for the dry matter intake, in vivo digestibility of dry matter, crude protein, crude fiber and nitrogen free extract, dry matter disappearance at 48 h and effective degradability at k = 0.05 h−1 of the samples (P < 0.05). The results revealed a wide range of diversity of nutritional quality of the imported oat hay that could have an affect on production potential in animals.

Effects of supplementary probiotics to two different diets on dry matter intake, daily gain, digestibility, ruminal pH, and fecal microbial populations and metabolites in ewes

ABSTRACTTo study the effects of supplementary probiotics on dry matter intake (DMI), daily gain (DG), digestibility, ruminal pH, and fecal microbial populations and metabolites in ruminants, two reversal trials were conducted by using four Suffolk ewes fitted with rumen cannula. The ewes were fed with oat hay and with concentrate and oat hay in the ratio of 60 : 40 in experiments 1 and 2, respectively. The ewes in the treatment groups were supplemented with 10 g/day/head probiotics for 49 days. Fresh fecal samples were collected to measure microbial populations and metabolites. On days 43–47 total feces was collected to measure digestibility, and on the days 48 and 49 ruminal pH was measured. No significant difference of DMI, DG, dry matter digestibility, and ruminal pH was observed between the control and treatment groups. The probiotics treatment tended to increase crude fiber (P = 0.11) and organic cell wall digestibility (P = 0.18). In the final week, probiotics treatment significantly increased the fecal population of Bacilli (P < 0.05) and mold (P < 0.01) in experiment 1 and 2, respectively. No significant difference of fecal VFA and ammonia concentrations between the control and treatment groups was observed. The supplementary probiotics changed population of some microbial strains in the feces and possibly the large intestine of ewes.

Increased levels of glycerol-3-phosphate lead to a stimulation of flux into triacylglycerol synthesis after supplying glycerol to developing seeds of Brassica napus L. in planta.

Glycerol-3-phosphate (glycerol-3P) is a primary substrate for triacylglycerol synthesis. In the present study, changes in the levels of glycerol-3P during rape (Brassica napus L.) seed development and the influence of manipulating glycerol-3P levels on triacylglycerol synthesis were investigated. (i) Glycerol-3P levels were high in young seeds and decreased during seed development at 30 and 40 days after flowering (DAF), when lipid accumulation was maximal. (ii) To manipulate glycerol-3P levels in planta, various concentrations of glycerol were injected directly into 30-DAF seeds, which remained otherwise intact within their siliques and attached to the plant. Injection of 0-10 nmol glycerol led to a progressive increase in seed glycerol-3P levels within 28 h. (iii). Increased levels of glycerol-3P were accompanied by an increase in the flux of injected [14C]sucrose into total lipids and triacylglycerol, whereas fluxes to organic acids, amino acids, starch, protein and cell walls were not affected. (iv) When [14C]acetate was injected into seeds, label incorporation into total lipids and triacylglycerol increased progressively with increasing glycerol-3P levels. (v) There was a strong correlation between the level of glycerol-3P and the incorporation of injected [14C]acetate and [14C]sucrose into triacylglycerol. (v) The results provide evidence that the prevailing levels of glycerol-3P co-limit triacylglycerol synthesis in developing rape seeds.

Effects of ruminal dosing of mechanical stimulating brush on digestibility and rumen fermentation status in Holstein steers fed low rice straw at different lengths

ABSTRACTThe objectives of the present study were to determine the effect of ruminal dosing of mechanical stimulating brush (Rumen faibu; RF) on digestibility and on rumen fermentation status in Holstein steers fed high concentrate and low rice straw. Eight steers (461 kg in average bodyweight) were used. Four steers were orally dosed three RF per head (RF‐dosing) and the other four were not dosed (non‐RF). All steers were fed enough concentrate and rice straw to gain 1.4 kg/day in bodyweight. Rice straw was cut 2 cm and 30 cm. The organic cell wall content of feeding diets was 17% in dry matter basis. Digestibility and nutritive value were not affected by RF dosing and length of rice straw. Ruminal pH was significantly lower in RF‐dosing group than in non‐RF group after feeding, and tended to be higher in long rice straw than in short rice straw throughout the day. There were no clear difference on total volatile fatty acid concentration and molar proportion of volatile fatty acid by RF dosing and length of rice straw throughout examined period. These present results suggest that digestibility and rumen fermentation status are not affected by RF dosing when organic cell wall content of feeding diets is approximately 17% in dry matter with rice straw over 2 cm.

Effect of Variety and Stage of Maturity on Nutritive Value of Whole Crop Rice, Yield, Botanical Fractions, Silage Fermentability and Chemical Composition

The effect of eight varieties of grain and forage type whole crop rice (Oryza sativa L Japonica) each harvested at four stages of maturity were investigated for morphology and yield, proportion of botanical fractions, fermentatability and chemical composition in an 8×4 factorial experiment. All crops were sown in 1997 at Saitama Prefecture, Japan under identical condition and harvested on 10, 22, 34 and 45 days after flowering in 1998. Total DM yield of forage type varieties was similar to that of the highest yield of grain type varieties. However, while yield of forage type varieties was attributed to higher proportion of straw than head, the reverse was in the case of grain type varieties. Yield in line with the proportion of head increased (p<0.001), but in contrast proportion of straw decreased (p<0.001) with the increase in maturity. Silage fermentability of grain type varieties was better than forage type varieties. Fermentability improved with the increase (p<0.001) in maturity suggesting that the moisture content should be reduced to improve fermentation quality. Forage type varieties contained higher (p<0.001) ash, crude fat (EE), organic cell wall (OCW) and acid detergent fiber (ADF), but contained lower crude protein (CP), organic cell content (OCC), CP in OCC and nitrogen-free cell wall extract (NCWFE) than the grain type varieties. The ash, CP, EE, Oa (60% digestible OCW), Ob (40% digestible OCW), OCW, ADF and acid detergent lignin (ADL) decreased (p<0.001), but OCC and NCWFE increased (p<0.001) with the increase in maturity. It is concluded that stage of maturity not only increases yield and proportion of head, but also improved the fermentation quality and increases quality chemical composition (except CP) of whole crop rice. Forage type varieties may be as good as grain type varieties in terms of yield, but fermentation quality and chemical composition may not be as good as that of grain type varieties. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 2 : 183-192)

Soft-walled, monothalamous benthic foraminiferans in the Pacific, Indian and Atlantic Oceans: aspects of biodiversity and biogeography

Delicate foraminiferans with test walls that are either agglutinated (Order Astrorhizida, Families Saccamminidae and Psammosphaeridae) or composed of organic material (Order Allogromiida) are often an important element of deep-sea benthic assemblages. Many species have soft, flexible walls and, except for a few allogromiids, are monothalamous (single-chambered). We examined quantitative multicorer samples from abyssal (4263–5570 m) water depths in the North and western Equatorial Pacific and a qualitative sample from a hadal site (7800 m water depth) in the Atacama Trench, SE Pacific. Soft-walled foraminiferans made up 29–42% of all complete, ‘live’ (rose Bengal stained) foraminiferans in the >32 μm fractions (0–1 cm sediment layer) of the North Pacific samples and 63% in the western Equatorial Pacific sample. They included the following morphotypes: (i) organic-walled allogromiids with one or occasionally two apertures; (ii) Nodellum- and Resigella-like forms in which the organic wall is generally brownish in colour and the test sometimes divided into more or less well-defined chambers by constrictions or partitions; (iii) flask-like agglutinated saccamminids with one aperture; (iv) oval saccamminids with two apertures; (v) agglutinated spheres which lack obvious apertures (psammosphaerids). In addition, numerous isolated spherical chambers, believed to be fragments derived from much larger komokiacean foraminiferans, were present in some samples and easily confused with saccamminids. At each Pacific station, we recognised 26–55 morphologically distinct forms (morphospecies) in addition to numerous ‘indeterminate’ specimens that could not be categorised on the basis of morphological criteria. A comparison of the Pacific assemblages with existing data on monothalamous assemblages from abyssal and bathyal depths in the Atlantic and Indian Oceans (>63 μm fraction) suggests that some morphospecies have wide geographical and bathymetric distributions. These wide-ranging morphospecies could provide good targets for future molecular-level studies addressing species differentiation among soft-shelled, monothalamous deep-sea foraminiferans.

Improving the production and utilization of sorghum and pearl millet as livestock feed: methodological problems and possible solutions

The overall objective of this work was the identification of simple, yet accurate, assessments of fodder quality of sorghum and pearl millet stover in crop improvement programs. Stover from 12 genotypes of sorghum and six genotypes of pearl millet grown under high and low fertilizer application was investigated for nitrogen, cell wall constituents, sugar, plant height, stem diameter, leaf number per plant and extent and rate of in vitro gas production of whole stover and of stover cell walls. Organic matter digestibility, organic matter intake, digestible organic matter intake (DOMI) and cell wall digestibility were measured in bulls. Significant genotypic variation was found for chemical, morphological and in vitro fermentation characteristics of stover but their relationship with digestibility and intake measurements was generally poor. While no single chemical, morphological or in vitro measurement described stover quality adequately, some combinations of these measurements resulted in good overall relationships with stover quality measurements. Across sorghum and pearl millet, 71% ( P<0.0001) of the variation in stover cell wall digestibility in bulls was accounted by the lag phase of in vitro gas production from cell wall preparations and by acid detergent lignin and acid detergent fiber content of stover. In pearl millet, 98% ( P<0.0001) of the variation in DOMI in bulls was accounted for nitrogen, lag phase and maximum rate of gas production and neutral detergent fiber content. The paper further discusses relationships between indirect animal performance measurements such as digestibility and voluntary feed intake (VFI) and animal productivity, e.g. live weight gain. VFI is shown to be a more crucial quality assessment in crop residues than digestibility and the relationship between both measurements was shown to be poor. It is argued that crop improvement programs should validate laboratory techniques as well as indirect animal performance measurements with direct animal performance measurements such as milk or meat production before deciding on laboratory selection criteria.

Quantitative meta-analysis on the effects of defaunation of the rumen on growth, intake and digestion in ruminants

A quantitative meta-analysis was applied on 90 publications and 169 comparisons dealing with defaunation of the rumen (removal of protozoa from the rumen) in order to point out the major quantitative effects of defaunation and identify interfering factors. Generally speaking defaunation significantly ( P<0.01) increased average daily gain (11% on average, 64 trials) but did not affect dry matter intake. As a consequence, defaunation improved feed conversion efficiency ( P<0.05). These different effects were especially obvious as diets were both high in forage and low in nitrogen and as animals had a low growth potential. Defaunation significantly ( P<0.001) decreased organic matter digestibility (−1.7 units, 52 trials) and cell wall carbohydrate digestibility (−5.7 units, 15 trials). The same trend was observed for rumen digestibility. On the other hand, duodenal nitrogen flow, expressed as a ratio of nitrogen intake, was enhanced by defaunation ( P<0.001). Duodenal microbial nitrogen flow, expressed as the percentage of live-weight, increased by 21% after defaunation ( P<0.05). The latter two results may account for the lower ammonia concentration in the rumen (−50.3 mgNNH 3/l, 75 trials) and the higher microbial synthesis efficiency (11.8 g microbial N/kg OMDr 19 trials) observed for the ciliate-free animals ( P<0.001). The level of concentrate in the diet strongly interfered with the effect of defaunation on the pH in the rumen. pH in the rumen was increased by defaunation with diets containing a high level of concentrate (PCO≥50%), whereas it decreased with diets containing a low level of concentrate. The molar proportion of propionic acid was enhanced by defaunation, whereas the molar proportion of butyric acid was lowered ( P<0.01) by defaunation, in the ruminal pool of volatile fatty acids (VFA). Finally, defaunation increased the ruminal volume and the liquid phase outflow rate ( P<0.05), but to a lesser extent. We consider that these results strongly suggest a more efficient use of nutrients in ciliate-free animals, especially when they are given poor diets limiting animal production.

Pyritisation of plant microfossils from the Devonian Hunsrück Slate of Germany

The extraordinary pyritised fossils of the Hunsruck Slate of Germany provide critical information on marine life in the Devonian. Evidence for terrestrial life is confined mainly to rare incomplete plant macrofossils, often of uncertain affinity. The discovery of plant microfossils preserved as pyrite in-fills of cells with decay-resistant organic walls provides additional evidence of life on land around the margins of the Hunsruck Slate sea. The microfossils include groups of elongate water-conducting cells: some show annular or helical indentations which represent thickenings of the original cell wall, others show casts of bordered pits. Spores, possible sporangia, and marine acritarchs are also present. In most cases pyritisation was rapid enough to prevent collapse of the cells, and they retain their original 3-dimensionality. Wall structures subsequently decayed except where they were resistant enough to survive as an organic residue.

In situ chemical speciation of sulfur in calcitic biominerals and the simple prism concept

The microstructure and composition of two mollusc shells were investigated using a combination of light microscopy, SEM, EPMA, and XANES. The shells of Pinna and Pinctada are composed of calcite prisms separated by organic walls. The prismatic units of Pinna are monocrystalline, and those of Pinctada are polycrystalline with internal organic radial membranes. High-spatial-resolution XANES maps for the different S species across adjacent prisms show that sulfate is the principal component in both the intraprismatic organic matrices and the outer membranes. Additionally, these maps confirm that the inner structures of the prismatic units are different for both genera. In many ways, the prisms of Pinna and Pinctada are different and invalidate the “simple prism” concept.

In situ mapping of growth lines in the calcitic prismatic layers of mollusc shells using X-ray absorption near-edge structure (XANES) spectroscopy at the sulphur K-edge

The microstructure and composition, including chemical speciation of sulphur (S), of two mollusc shells were investigated using a combination of scanning electron microscopy, X-ray absorption near-edge structure spectroscopy (XANES) and electron probe microanalysis (EPMA). The shell of Pinna is composed of monocrystalline, and Pinctada, of polycrystalline, calcite prisms separated by organic-rich walls. Sulphur speciation information from XANES spectra using a scanning X-ray microscope showed that the protein S content of the interprismatic walls is higher than the SO4 content, whereas the reverse is true for the intraprismatic structures. High-spatial-resolution XANES maps for the different S species across adjacent calcite prisms confirm their distinctive distributions in the molluscan shells and illustrate the presence of narrow, submicron transverse growth features. On a larger scale, a series of wider growth zones, incorporating the submicron zones, are aligned parallel to each other and cross-cut many calcite prisms. EPMA element maps for magnesium (Mg) and S demonstrate that these growth increments are compositionally zoned, comprising alternating layers of high mineral (Mg-rich) and high organic (S-rich) components. Additionally, these maps confirm that the organic interprismatic walls have lower Mg and higher S than the intraprismatic structures.

Diffusion of an organic cation into root cell walls.

Uptake of a cationic dye (methylene blue) by isolated root cell walls, roots of whole transpiring seedlings, and excised roots was investigated using 7-day-old seedlings of cucumber, maize, and wheat. The number of ionogenic groups per 1 g dry and wet weight of the root cell walls, their swelling capacity (K(cw)), time-dependence of methylene blue (M(cw)) ion exchange capacity, and diffusion coefficients of the cation diffusion in the polymer matrix of the cell walls (D(cw)) were determined. The M(cw) value depended on pH (or carboxyl group dissociation); it changed in accordance with the number of carboxyl groups per 1 g cell wall dry weight. This parameter decreased in the order: cucumber > wheat > maize. For description of experimental kinetic curves and calculation of cation diffusion coefficients, the equation for ion diffusion into a cylinder of infinite length was used. The chosen model adequately described cation diffusion in cell walls and roots. Diffusion coefficient values for cucumber, wheat, and maize were 3.1*10(-8), 1.3*10(-8), and 8.4*10(-8) cm(2)/sec, respectively. There was a statistically significant linear dependence between K(cw) and D(cw) values, which characterize the same property of the polymer matrix, rigidity of its polymer structure or the degree of cross-linkage or permeability. This also confirms the right choice of the model selected for calculation of methylene blue diffusion coefficients, because K(cw) and D(cw) values were obtained in independent experiments. The coefficients determined for methylene blue diffusion in transpiring seedling roots (D(ts)) and excised roots (D(er)) depended on the plant species. The rate of methylene blue diffusion into the excised roots was either 1.5-fold lower (cucumber) or 3-4-times lower (maize, wheat) than in cell walls. The values of diffusion coefficients in roots of whole seedlings were comparable which those for the cell walls. On the basis of the experimental data and results of calculations, it is concluded that the mechanism of methylene blue uptake by plant roots involves ion exchange reactions between the organic cation and cell wall carboxyl groups, and the uptake rate is determined by the cation diffusion in the polymer matrix of the cell walls.

Energy supply to livestock from tropical rangeland during the dry season.

Nine key forage species (grasses and legumes), together with two types of crop residues, usually fed by farmers to their livestock, were collected from a rainfed area in western Sudan during the dry season (May-April). The grasses investigated were Leptadena pyrotechnia, Cenchrus setigrus, Arista pallida, Eragrotis tremula, Schoenefeldia gracilis, Chloris vergata and Cenchrus biflorus. The crop residues investigated were the grasses, sorghum straw (Sorghum bichlor) and millet straw (Pennisetum typhodium) and the legumes Stylosanthes flavicans and Cajanus cajana. Estimates of organic matter (OM) degradability were done using the nylon bag technique, which was fitted into the model Y = a + b (1 - e(-ct)), in which the asymptote (a + b) represented the total potential degradability. Organic cell wall constituents and hence both metabolizable energy and total digestible energy or nutrients (TDN) were determined. S. flavicans showed the best organic matter degradability, and sorghum straw was better degraded than millet straw. The rest of the grasses showed poor OM degradability. Acid detergent insoluble nitrogen was inversely related to TDN, the latter falling within a narrow range for the different forages. Fermentable metabolizable energy differed only slightly, while the legume S. flavicans had the highest effective rumen digestible protein. Undegraded proteins were high for the straws and the grasses L. pyrotechnia and C. setigerus. Metabolizable protein and microbial protein were highest in the sorghum straw, C. setigerus and S. flavicans.

Influência das condições de processamento cerâmico na resistência mecânica e na permeabilidade dos filtros de Al2O3-SiC

Filtros cerâmicos devem apresentar alta permeabilidade e eficiência de retenção de inclusões sólidas, além de uma boa resistência mecânica. No entanto, estas propriedades variam de modos distintos para uma determinada estrutura celular. Poros grandes aumentam a permeabilidade, mas diminuem a eficiência de retenção das inclusões. Em relação ao desempenho do filtro, a porosidade aparente apresenta alta relevância, uma vez que a resistência mecânica diminui e a permeabilidade aumenta para valores de porosidade elevados. Neste trabalho investigou-se a relação entre a resistência mecânica e a permeabilidade para filtros do sistema Al2O3-SiC de 10 ppi (poros por polegada linear). A quantidade da suspensão impregnada na esponja, durante a fabricação do filtro, foi escolhida como variável de controle, pois por meio desta modifica-se a porosidade e o tamanho de poro do filtro. Os resultados obtidos foram comparados aos de filtros de 8 a 90 ppi.

Effect of ruminal dosing of mechanical stimulating brush on carcass characteristics and fatty acid composition of dressed carcass fat in fattening Holstein steers fed with high‐concentrate diets

ABSTRACTThis experiment was undertaken to examine the effect of dosing of a mechanical stimulating brush (RF) in the rumen on dressed carcass characteristics and on the fatty acid composition of dressed carcass fat in fattening beef cattle. The fattening trial was carried out with high‐concentrate diets (organic cell wall contents: 27.5% on a dry mater basis) in eight Holstein steers (12 months of age). Four of the experimental animals were orally dosed with three RF/head (RF group); the other four animals without RF dosing were allotted as the control group. Grass hay was fed to the animals (0.2 kg/head/day) until 19 months of age. Concentrate diet was given ad libitum during the experiment. There were no statistical differences between the RF group and the control group in yield score and meat quality score of dressed carcass characteristics. Regarding fatty acid composition of dressed carcass fat, the proportion of C18 : 2 fatty acids in subcutaneous fat in the RF group was greater (P &lt; 0.05) than that in the control group. C16 : 0 fatty acids in kidney fat in the RF group was lower (P &lt; 0.05), and C18 : 2 fatty acids and total unsaturated fatty acids of 18 carbon number in kidney fat in the RF group were higher (P &lt; 0.05) compared with the control group. The proportion of C18 : 2 fatty acids in rib eye fat in the RF group was greater (P &lt; 0.05) than that in the control group. C18 : 1 fatty acids, C18 : 2 fatty acids and total unsaturated fatty acids of 18 carbon number in rib fat in the RF group were greater (P &lt; 0.05) than those in the control group. The results suggest that in fattening Holstein steers fed with high‐concentrate diets, the effect of ruminal RF dosing on dressed carcass characteristics is not significant, but the proportion of unsaturated fatty acid of carcass fat is increased.

Calcification and Decalcification During Epithallial Cell Turnover in Coralline Red Algae

AbstractEpithallial cells of the coralline red algae are characterized by unusual structural specialization, which include deep invaginations of the distal cell surface, and by unique development, which culminates in senescence, shedding, and replacement of the cells. Electron microscopic study of epithelial cell differentiation in morphologically and taxonomically disparate species suggests that the unusual features of epithelial cell structure and development stem from the fact that these dynamics occur within a calcified matrix. Distal wall ingrowths begin to form on the initial cells, cells whose cleavage eventually gives rise distally to new epithelial cells. After the distal wall ingrowths form, the overlying crosswall becomes rich in organic material. For this organic wall material to be deposited into the existing crosswall, the wall must first be decalcified; therefore, the presence of abundant organic material in the crosswall provides a marker of localized decalcification. We propose that the location and time of origin of distal wall ingrowths indicate a connection between the ingrowths and two coordinated processes: localized secretion of wall material, and decalcification of the overlying cell wall in preparation for the movement of the young epithelial cell into a new location relative to the surrounding calcified matrix. The large plasmalemmal surface area associated with the distal wall ingrowths allows for a greater abundance of membrane‐associated components, such as proton pumps, that could drive localized cell wall decalcification.

Epithallial and initial cell fine structure in species of Lithothamnion and Phymatolithon (Corallinales, Rhodophyta)

Transmission electron microscopy was used to study the ultrastructure of epithallial, subepithallial, and initial cells in three species of Lithothamnion: L. glaciale, L. corallioides, and L. sonderi, and four species of Phymatolithon: P. laevigatum, P. purpureum, P. lenormandii, and P. calcareum (Corallinaceae, subfamily Melobesioideae). One of the principal characters used to delimit Lithothamnion is the flared morphology of its epithallial cells. Ultrastructural examination showed that this flared appearance is produced by the trapezoidal outline of the outermost cell wall of the intact epithallial cell, incombination with the presence of the remnant proximal wall of shed epithallial cells. Unlike most coralline species studied ultrastructurally, none of the three species of Lithothamnion had chloroplasts in their epithallial cells. Absence of chloroplasts distinguished epithallial cells from chloroplast-rich initial cells, allowing easy discrimination of these cell types. Extensive wall ingrowths developed on the distal face of initial cells; upon division of an initial cell to produce an epithallial cell and a new initial cell, the ingrowths were inherited by the newly formed epithallial cell. Decalcification of cell walls occurs as part of the process of epithallial cell turnover; subsequent recalcification may then occur. Secondary calcification was present in the wall layer between the remnant proximal wall and the distal epithallial cell surface in L. glaciale and L. corallioides. Lithothamnion corallioides was unique in having an electron-dense hemispherical structure on the distal face of each epithallial cell; this feature may prove to be a useful taxonomic character. In Phymatolithon, the number of epithallial cells per filament varied from none to three. Terminal epithallial cells were domed and much larger than the subterminal epithallial and initial cells. The outer face of the surface epithallial cell was covered by a thick layer of organic material containing the outlines of extracted small crystals of CaCO3, but calcification was very light. Healthy-looking epithallial cells had chloroplasts with thylakoid spacings similar to that of the discoidal chloroplasts of subepithallial cells. Initial cells preparing to divide were surrounded by a thick organic wall. The derivatives of the division were equal in size and until they enlarged, the pair was collectively surrounded by the persistent wall of the old initial cell. The lower cell, the new initial cell, developed distal wall ingrowths, whereas the upper cell, the new epithallial cell, inherited the ingrowths of the parent initial cell. Distal wall ingrowths were still present even in senescent epithallial cells. Epithallial cell morphology has played an important role in the taxonomic separation of Phymatolithon from Lithothamnion. Epithallial fine structure demonstrates additional, systematically useful characters, such as the presence of chloroplasts in the epithallial cells of Phymatolithon and their absence from epithallial cells in Lithothamnion, that are consistent with the recognition of Phymatolilhon. Ultrastructural study also provides new criteria for the proper identification of epithallial and initial cells in Phymatolithon.

Comparison of the soluble matrices of the calcitic prismatic layer of Pinnanobilis (Mollusca, Bivalvia, Pteriomorpha)

The calcitic prisms of the outer layer of the shell of Pinna nobilis, surrounded by thick organic walls, contain a soluble intracrystalline matrix. The structure and composition of the outer interprismatic walls are not well known. The current viewpoint is they are composed of an insoluble matrix. Another thick organic structure, the interlamellar sheet of the nacreous layer, is composed of insoluble and soluble matrices. The composition of two sets of soluble organic matrices from the calcitic layer of Pinna nobilis, extracted with and without the organic walls are compared. According to the various analyses (SEM and AFM, UV and FTIR spectrometry, HPLC, electrophoreses, XANES), the main characteristics of the two matrices are similar, but not identical. Thus, the organic walls contain soluble components. However, the three-layered structure of the interlamellar sheet of the nacreous layer has not been observed.

Effect of ruminal dosing of mechanical stimulating brush on rumination time, ruminal passage rate and rumen fermentation status in Holstein steers fed a concentrate diet

ABSTRACTThis experiment was conducted to determine the effect of ruminal dosing of a mechanical stimulating brush on rumination time, ruminal passage rate and rumen fermentation status in steers fed a concentrate diet at maintenance level. Animals were dosed three Rumen Faibu (RF) per head through the rumen fistulae (RF treatment) and not dosed (control) in a change‐over design. The organic cell wall content of the concentrate diet was 12.7% of dry matter. Daily time spent on rumination was very short in both treatments with 24 min in RF treatment and 15 min in control. The turnover rate of ruminal fluid in RF treatment was higher than that in control. There were no differences in ruminal pH and total volatile fatty acid concentration between RF treatment and control. Acetic and butyric acid concentrations were not different between the treatments. Propionic acid concentration tended to be higher in the animals on RF treatment than in control animals. The RF dosing in Holstein steers fed a low fiber diet did not affect the rumination time, but increased rumen digesta passage rate and ruminal propionic acid production.

Supplementation of Acacia cyanophylla Lindl. foliage-based diets with barley or shrubs from arid areas ( Opuntia ficus-indica f. inermis and Atriplex nummularia L.) on growth and digestibility in lambs

Twenty-eight Barbarine yearling lambs (4 months of age, average live weight 22.0±2.3 kg) given freshly cut Acacia cyanophylla Lindl. (acacia) foliage ad libitum supplemented with either 0.3 kg barley (B), 4.5 kg freshly cut pads of Opuntia ficus-indica f. inermis (cactus) (C), 0.3 kg barley and 1.4 kg freshly cut Atriplex nummularia L. foliage (atriplex) (B+A) or 4.5 kg cactus and 1.4 kg atriplex (C+A) were used in an 80-day study comprising growth, digestibility and N balance trials. The sheep were blocked by weight and within each block randomly allocated to four treatments giving seven animals per treatment. Condensed tannins (CT) content was high in acacia. Great amount of total oxalates was found in cactus (131 g/kg dry matter (DM)). Sheep consumed significantly less acacia when supplemented with cactus either alone (C) or with atriplex (C+A) as compared with (B) and (B+A) diets (28.7, 26.3, 36.6 and 38.3 g DM/kg W 0.75, respectively). The amount of drinking water was reduced in sheep given cactus as compared with those receiving barley and was increased with atriplex supply. Supplementing sheep with cactus alone substantially reduced organic matter (OM), crude protein (CP) and cell wall digestibility of the diet as compared with barley diet (B). These negative effects were reduced when cactus was fed in combination with atriplex. Nitrogen retention (g per day) with C-diet was proportionately about 0.61 lower than with (C+A)-diet and 0.32 lower with (C+A)-diet than with (B+A)-diet. Replacing barley by cactus had no effect upon the urinary excretion of allantoin, and thus on estimated microbial N supply to the small intestine. Atriplex supplied either with barley or cactus improved the efficiency of microbial protein synthesis. Replacing barley with cactus significantly reduced daily gains. Sheep on (B+A)-diet gained more (54 g per day) than those on the other dietary treatments. It was concluded that acacia may be utilised in sheep feeding provided that an adequate supply of both energy and nitrogen is made. Highest positive responses were obtained when barley was used as supplement of acacia with or without atriplex. Cactus alone was not able to replace barley as supplement to acacia. It should be offered in combination with a nitrogen-rich supplement, such as atriplex, to ensure normal microflora activity in the rumen. A diet of acacia supplemented with cactus and atriplex could be a cost-effective solution to nourish sheep during dry seasons.