Apparent digestibility of wheat bran and extruded flax in horses determined from the total collection of feces and acid-insoluble ash as an internal marker

Several studies have reported data on comparisons between two methods: the total collection of feces and the internal markers method. The aim of this study was to assess the apparent digestibility of two concentrates and to compare the apparent digestion coefficients using the total collection of feces and acid-insoluble ash (AIA) as the internal marker method. In 2009, six adult geldings aged between 3 and 11 years, with an average weight per trial of 543, 540 and 542 kg, respectively, were used to determine the apparent digestibility by means of three in vivo digestibility trials on hay, hay plus wheat bran (60 : 40) and hay plus extruded flax (80 : 20). Feces were collected over a 6-day period with a previous 14-day adaptation period. The three digestibility trials were carried out to determine the digestion coefficients of the three diets and, indirectly, of the two concentrates. The digestion coefficients of the diets were determined for the dry matter, organic matter, crude protein and gross energy, whereas the apparent digestion coefficients of the same parameters were calculated for wheat bran and extruded flax, by calculating the difference from the previous results. The data were analyzed using the Student t-test for paired samples. The digestion coefficients obtained were similar when the total collection of feces and the AIA method were used. Higher data variability, confirmed by a greater standard deviation, was observed using the AIA method to estimate the apparent digestion coefficients. It can be concluded that the use of AIA as an internal marker in digestibility trials on average leads to values similar to those obtained with the total collection of feces and can therefore be considered a less-expensive method to determine apparent digestion coefficients. Nevertheless, the total collection of feces should still be considered the best choice to determine the digestibility of some specific feedstuffs.     

Biodegradation of wheat straw lignocarbohydrate complexes (LCC)

Summary In laboratory and semi-industrial scale experiments the influence of the substrate water content, temperature, and incubation time on the progress of solid state fermentation of straw colonized by white rot fungi was investigated. The parameters used to evaluate the fermentation process were degradation of total organic matter and lignin, in vitro digestibility, the content of water soluble substances in the substrate and the pH.The degradation of total organic matter was species specific. Only Trametes hirsuta enhanced the degradation at elevated temperature (30 °C). With Abortiporus biennis, Ganoderma applanatum, and Pleurotus serotinus, elevated temperature had and adverse effect. Prolonged incubation only improved degradation of straw by the relatively slowgrowing fungi Ganoderma applanatum, Lenzites betulina, and Pleurotus sajor caju.Elevated temperature and prolonged incubation shifted the relative degradation rates in favour of total organic matter degradation. With Ganoderma applanatum, Pleurotus ostreatus, and Pleurotus serotinus lignin degradation, even on an absolute scale, was less at 30 °C than at 22 °C.In general, the in vitro digestibility also decreased, when the incubation time and temperature were raised. With Ganoderma applanatum the in vitro digestibility dropped below the value of the sterile straw control.Solid state fermentation of straw was at an optimum at a medium water content of 75 ml/25 g of substrate. However, most of the fungi tested could digest straw over a wide range of water content. At higher water contents (125–150 ml/25 g of substrate) an increased production of aerial mycelium was observed.In semi-industrial batch experiments (40 kg) with Abortiporus biennis the in vitro digestibility dropped below the reference value for sterile straw during the first 19 days of incubation. Later, the in vitro digestibility again rose and reached its optimum after about 60 days. The in vitro digestibility in the semi-industrial experiments was always lower than in the laboratory experiments (+9% and +25%, respectively).In long term experiments (2.5 kg batches, 8 months of incubation) very different values for the in vitro digestibility were found, and these depended on the fungus used (Abortiporus biennis, +16%; Pleurotus ostreatus, +4%; and Ganoderma applanatum, –27%).     

The effectiveness of biological treatment of wheat straw by white-rot fungi

Out of 13 species ofBasidiomycetes growing on wheat straw, 9 species enhanced thein vitro dry matter digestibility of the substrate. The detergent fiber content (acid and neutral) of the substrate was significantly reduced by most of the fungi tested. Hemicellulose showed the largest proportionate loss, whereas lignin the smallest one.     

Substrate-dependent degradation patterns in the decay of wheat straw and beech wood by ligninolytic fungi

Summary The ability of 45 fungal strains to degrade wheat straw and beech wood was studied. Degradation patterns were defined in terms of chemical evolution of substrates and changes in lignin and polysaccharides. Trametes versicolor produced an important degradation of lignin and increased substrate digestibility, but it caused high weight losses and gave rise to similar decay patterns on both substrates. A preferential degradation of lignin was produced during straw transformation by Pleurotus eryngii. The increase of soluble lignin and decreases of lignin content and H/C ratio defined the degradation tendency after principal component analysis. The cation exchange capacity and water and alkali solubility presented the highest loading factors for the characterization of fungal transformation of beech wood. Offprint requests to: A. T. Martínez     

In vitro degradation of cell-wall and digestibility of cereal straws treated with anaerobic ruminal fungi

Ruminal fungal isolates (Orpinomyces sp.; C-14, Piromyces sp.; C-15, Orpinomyces sp.; B-13 and Anaeromyces sp.; B-6), were evaluated under anoxic conditions for their effect on in vitro dry matter digestibility, neutral detergent fibre, acid detergent fibre and acid detergent lignin using rice and wheat straw as substrate. There was no significant effect of the fungal isolates on the disappearance of the substrates along with rumen liquor when compared to control. The doses of 10(6) cfu/ml of the isolate were found to have maximum degradation of straws in comparison to the doses of 10(3) cfu/ml.     

Biodelignification of wheat straw and its effect on in vitro digestibility and antioxidant properties

A variety of methods for feed development have been introduced during last few years. Bioprocessed agricultural residues may prove a better alternative to provide animal feed. For the purpose, some white rot fungi were allowed to degrade wheat straw up to 30 days under solid state conditions. Several parameters including loss in total organic matter, ligninolysis, in vitro digestibility of wheat straw and estimation of different antioxidant activities were studied. All the fungi were able to degrade lignin and enhance the in vitro digestibility. Among all the tested fungi, Phlebia brevispora degraded maximum lignin (30.6%) and enhanced the digestibility from 172 to 287 g/kg. Different antioxidant properties of fungal degraded wheat straw were higher as compared to the uninoculated control straw. Phlebia floridensis found to be more efficient organism in terms of higher antioxidant activity (70.8%) and total phenolic content (9.8 mg/ml). Thus, bioprocessing of the wheat straw with the help of these organisms seems to be a better approach for providing the animal feed in terms of enhanced digestibility, higher protein content, higher antioxidant activity and availability of biomass.     

Effects of fibre on digestibility and passage time in callithricidae

The effects of fibre in a pelleted diet on food intake, digestibility of crude fibre, dry matter and energy, on passage time and consistency of faeces were studied in 2 species of Callithricidae, Callithrix jacchus and Saguinus fuscicollis. Coarse cellulose, microcellulose, wheat bran and shrimp meal (chitin = crude fibre) were tested in diets containing 2,4 and 6% total crude fibre, respectively. Digestibility and passage time were determined by inclusion of 0.5% Cr2O3 in the diet. Both celluloses had little influence on the digestibility of energy and dry matter. Digestibility of crude fibre was very low. Wheat bran led to evident depression of energy and dry matter digestibility. High digestibility of crude fibre occurred at the higher levels of inclusion in the diet. Shrimp meal was highly digested with little influence on digestibility of energy and dry matter, indicating considerable degradation of chitin. Wheat bran showed a marked effect, while microcellulose had no effect on passage time, consistency and volume of faeces.     

Biodegradation of paddy straw obtained from different geographic locations by means of <Emphasis Type="Italic">Phlebia</Emphasis> spp. for animal feed

Various cereal straws are used as feed by supplementing the green forage or other feed stuffs. An experiment was designed to see the effect of different geographic locations and climatological conditions on biochemical constituents, fungal degradation and in vitro digestibility of paddy straw. Paddy straw (PS) obtained from three different geographic locations of India was subjected to solid state fermentation using four white rot fungi i.e. Phlebia brevispora, P. fascicularia, P. floridensis and P. radiata. Changes in the biochemical constituents like water soluble content, hemicellulose, cellulose, lignin, total organic matter, and in vitro digestibility of paddy straw was analyzed over a period of 60 days along with lignocellulolytic enzymes i.e. laccase, xylanase and carboxymethyl cellulase. All the fungi degraded the straw samples and enhanced the in vitro digestibility. The paddy straw, obtained from north western zone (NWZ) suffered a maximum loss (228 g/kg) of lignin by P. radiata, while a maximum enhancement of in vitro digestibility from 185 to 256 g/kg was achieved by P. brevispora, which also caused minimum loss in total organic matter (98 g/kg). In PS obtained from central eastern zone (CEZ) and north eastern zone (NEZ), a maximum amount of lignin (210 and 195 g/kg, respectively) was degraded by P. floridensis and resulted into a respective enhancement of in vitro digestibility from 172 to 246 g/kg and 188 to 264 g/kg. The study demonstrates that geographic locations not only affect the biochemical constituents of paddy straw but the fungal degradation of fibers, their in vitro digestibility and lignocellulolytic enzyme activity of the fungus may also vary.     

Growth and sporulation behaviour of Penicillium roquefortii in solid substrate fermentation: effect of the hydric parameters of the medium

Both growth and sporulation increase linearly according to the initial water content of the solid substrate when Penicillium roquefortii is cultivated on buckwheat seeds. This indicates that water is the limiting factor for fungal development since neither carbon nor nitrogen sources were exhausted during these experiments. This feature validates the concept of available water for fungal growth, defined as initial water content of substrate minus its residual water content when vegetative growth stops. An efficient methodology, based on drawing a regression line of mycelium dry weight production as a function of the initial water content of substrate is presented; it allows estimation of both available water and water content of mycelium. Results show that growth stops when the residual water in the substrate is close to 0.52 g H₂O/g initial dry matter, corresponding to a water activity (a_w) close to 0.96, and that the initial water content in mycelium is near 76%. Thus, both a_w and water content of the substrate have to be taken into account during the course of solid-state cultivations.Correspondence to: C. Larroche     

Model for on-line moisture-content control during solid-state fermentation

In this study we describe a model that estimates the extracellular (nonfungal) and overall water contents of wheat grains during solid-state fermentation (SSF) with Aspergillus oryzae, using on-line measurements of oxygen, carbon dioxide, and water vapor in the gas phase. The model uses elemental balances to predict substrate dry matter losses from carbon dioxide measurements, and metabolic water production, water used in starch hydrolysis, and water incorporated in new biomass from oxygen measurements. Water losses caused by evaporation were calculated from water vapor measurements. Model parameters were determined using an experimental membrane-based model system, which mimicked the growth of A. oryzae on the wheat grains and permitted direct measurement of the fungal biomass dry weight and wet weight. The measured water content of the biomass depended heavily on the moisture content of the solid substrate and was significantly lower than the estimated values reported in the literature. The model accurately predicted the measured overall water content of fermenting solid substrate during fermentations performed in a 1.5-L scraped drum reactor and in a 35-L horizontal paddle mixer, and is therefore considered validated. The model can be used to calculate the water addition required to control the extracellular water content in a mixed solid-state bioreactor for cultivation of A. oryzae on wheat.     

Effect of high fibre diets formulated with different fibrous ingredients on performance,nutrient digestibility and faecal microbiota of weaned piglets

The aim of the experiment on 180 weaned piglets (8.9 kg body weight) was to investigate the influence of high fibre diets formulated with different fibrous ingredients on performance, nutrient digestibility, diarrhoea incidence and numbers of faecal microbiota. The dietary treatments included a Control diet and five high fibre diets formulated with different fibre sources including wheat bran, soybean hulls, naked oat hulls, palm kernel expeller and bamboo fibre. The high fibre diets averaged 14.6% neutral detergent fibre with different non-starch polysaccharides (NSP) components and were fed ad libitum for 28 d. Faecal samples were collected during the last 3 d of the experiment and the apparent total tract digestibility of nutrients and fibre components were determined. Pigs fed the Control and wheat bran diets had a higher (p ≤ 0.05) average daily gain (ADG) than pigs fed the palm kernel expeller and bamboo meal diets. The reduced ADG for pigs appeared to be related to reductions in the digestibility of gross energy and dry matter, respectively. The feed-to-gain ratio was significantly higher (p ≤ 0.05) for pigs fed the fibre diets. The digestibility of NSP components was different among the treatments. The diarrhoea incidence was not affected by treatments. The abundance of faecal bifidobacteria was significantly higher (p ≤ 0.05) for pigs fed the wheat bran diet than for pigs fed the bamboo meal diet. It was concluded that the diets formulated with different fibre sources when fed to weaned piglets have different effects on pig performance, nutrient digestibility and numbers of faecal microbiota. The wheat bran diet rich in arabinoxylans enabled a better performance than the other tested diets with fibre addition.     

Influence of oxygen and carbon dioxide on lignin degradation in solid state fermentation of wheat straw withStropharia rugosoannulata

Summary In solid state fermentation,Stropharia rugosoannulata degrades lignin of wheat straw slightly better in the presence of oxygen than that in air. The sub-atmospheric partial pressure of oxygen (0.05 atm.) inhibits lignin and organic matter degradation. the increasing partial pressure of carbon dioxide (0.1–0.3 atm.) along with 0.2 atm. of oxygen does not have any effect on lignin degradation, but slightly decreases organic matter loss and increases thein vitro digestibility of fermented wheat straw, thereby making the process more efficient.     

Effect of different supplements on bioprocessing of wheat straw by Phlebia brevispora: changes in its chemical composition, in vitro digestibility and nutritional properties

Bioprocessing of wheat straw was carried out by Phlebia brevispora under solid state conditions. Effect of different supplements on lignocellulolytic enzymes production, degradation of straw cell wall fibers and its resultant effect on nutritional quality of wheat straw were studied. Ammonium chloride and malt extract were more effective in terms of ligninolysis and enhanced in vitro digestibility. The concentration of the selected supplements and the moisture content was worked out using response surface methodology in order to minimize the loss in total organic matter so as to selectively degrade lignin. The experiment was scaled up to batches of 200 g under optimized conditions and the degraded substrate was analyzed for its biochemical properties. P. brevispora degraded 290 g/kg of lignin and enhanced the in vitro digestibility from 150 to 268 g/kg (78%). Crude protein, amino acids, total phenolic contents and antioxidant properties were significantly higher in degraded straw.     

Comparative culturing of Pleurotus spp. on coffee pulp and wheat straw: biomass production and substrate biodegradation

The results of the cultivation of six strains of Pleurotus (P. djamor (2), P. ostreatus (2) and P. pulmonarius (2)) on coffee pulp and wheat straw are presented. Metabolic activity associated with biomass of each strain was determined, as well as changes in lignin and polysaccharides (cellulose and hemicellulose), phenolic and caffeine contents in substrate samples colonized for a period of up to 36 days. Analysis were made of changes during the mycelium incubation period (16 days) and throughout different stages of fructification. Greater metabolic activity was observed in the wheat straw samples, with a significant increase between 4 and 12 days of incubation. The degradation of polysaccharide compounds was associated with the fruiting stage, while the reduction in phenolic contents was detected in both substrates samples during the first eight days of incubation. A decrease was observed in caffeine content of the coffee pulp samples during fruiting stage, which could mean that some caffeine accumulates in the fruiting bodies.     

Effects of insoluble dietary fibre differing in lignin on performance, gut microbiology, and digestibility in weanling piglets

The study aimed to investigate the effects of insoluble dietary fibre differing in lignin content on performance and parameters of gut microbiology in 48 weanling piglets (8.5 kg mean body weight) fed common diets ad libitum. Fibre sources tested were wheat bran (low lignin) and pollen from Chinese Masson pine (Pinus massoniana) as model of fibre rich in lignin, added to diets as follows: no addition (control), 3.0% wheat bran, 1.27% pine pollen and 2.55% pine pollen. In colonic chyme, bacterial colony counts remained unaffected by treatment, but ammonia contents were reduced by fibre additions (up to -38%). The effects on ammonia were best explained by added cellulose and lignin. Fibre additions reduced apparent (faecal) digestibility of dry matter (DM) and crude protein (CP) up to -3.5 and -4.3% units with cellulose and lignin being the major determinants for changes in CP digestibility.     

Suppression of the biocontrol agent trichoderma harzianum by mycelium of the arbuscular mycorrhizal fungus glomus intraradices in root-free soil

Trichoderma harzianum is an effective biocontrol agent against several fungal soilborne plant pathogens. However, possible adverse effects of this fungus on arbuscular mycorrhizal fungi might be a drawback in its use in plant protection. The objective of the present work was to examine the interaction between Glomus intraradices and T. harzianum in soil. The use of a compartmented growth system with root-free soil compartments enabled us to study fungal interactions without the interfering effects of roots. Growth of the fungi was monitored by measuring hyphal length and population densities, while specific fatty acid signatures were used as indicators of living fungal biomass. Hyphal 33P transport and beta-glucuronidase (GUS) activity were used to monitor activity of G. intraradices and a GUS-transformed strain of T. harzianum, respectively. As growth and metabolism of T. harzianum are requirements for antagonism, the impact of wheat bran, added as an organic nutrient source for T. harzianum, was investigated. The presence of T. harzianum in root-free soil reduced root colonization by G. intraradices. The external hyphal length density of G. intraradices was reduced by the presence of T. harzianum in combination with wheat bran, but the living hyphal biomass, measured as the content of a membrane fatty acid, was not reduced. Hyphal 33P transport by G. intraradices also was not affected by T. harzianum. This suggests that T. harzianum exploited the dead mycelium but not the living biomass of G. intraradices. The presence of external mycelium of G. intraradices suppressed T. harzianum population development and GUS activity. Stimulation of the hyphal biomass of G. intraradices by organic amendment suggests that nutrient competition is a likely means of interaction. In conclusion, it seemed that growth of and phosphorus uptake by the external mycelium of G. intraradices were not affected by the antagonistic fungus T. harzianum; in contrast, T. harzianum was adversely affected by G. intraradices.     

Stoned olive pomace fermentation with Pleurotus species and its evaluation as a possible animal feed

The use of stoned olive pomace (SOP) as an unconventional feedstuff for livestock is limited by its inherently low crude protein (CP) content and by the presence of anti-nutritional compounds such as phenols. Aim of this study was to assess whether solid-state fermentation of SOP with selective lignin-degrading fungi might ameliorate nutritional properties of the waste. Incubation of SOP, mixed (25%, w/w) with various conventional feedstuffs (i.e., wheat bran, wheat middlings, barley grains, crimson clover, wheat flour shorts and field beans), with Pleurotus ostreatus and Pleurotus pulmonarius led to significant CP increases, ranging from 7 to 29%, and marked removal (from ca. 50–90%) of phenols after 6 weeks. Both species, however, led to moderate delignification associated with significant consumption of hemicelluloses. Consequently, no improvements of both organic matter digestibility (OMD) and net energy of SOP–feedstuff mixtures occurred after the fungal colonization.     

Degradation of wheat straw by Fibrobacter succinogenes S85: a liquid- and solid-state nuclear magnetic resonance study

Wheat straw degradation by Fibrobacter succinogenes was monitored by nuclear magnetic resonance (NMR) spectroscopy and chemolytic methods to investigate the activity of an entire fibrolytic system on an intact complex substrate. In situ solid-state NMR with 13C cross-polarization magic angle spinning was used to monitor the modification of the composition and structure of lignocellulosic fibers (of 13C-enriched wheat straw) during the growth of bacteria on this substrate. There was no preferential degradation either of amorphous regions of cellulose versus crystalline regions or of cellulose versus hemicelluloses in wheat straw. This suggests either a simultaneous degradation of the amorphous and crystalline parts of cellulose and of cellulose and hemicelluloses by the enzymes or degradation at the surface at a molecular scale that cannot be detected by NMR. Liquid-state two-dimensional NMR experiments and chemolytic methods were used to analyze in detail the various sugars released into the culture medium. An integration of NMR signals enabled the quantification of oligosaccharides produced from wheat straw at various times of culture and showed the sequential activities of some of the fibrolytic enzymes of F. succinogenes S85 on wheat straw. In particular, acetylxylan esterase appeared to be more active than arabinofuranosidase, which was more active than alpha-glucuronidase. Finally, cellodextrins did not accumulate to a great extent in the culture medium.     

Assessment of winter wheat cultivars for changes in straw composition and digestibility in response to fungicide and growth regulator treatments

The effects of a combined fungicide and growth regulator treatment on the composition and dry matter digestibility of straw samples of winter wheat cultivars, Beaver, Brigadier, Hussar, Mercia, Riband, Genesis, Hunter, Spark, Cadenza and Flame, were compared. The samples were analysed for nitrogen, ash, fibre fractions and minerals. Nitrogen content of treated samples was reduced compared to the untreated control samples and in contrast the proportion of ash increased for all the treated samples. All samples were analysed by derivative thermogravimetry (DTG) to determine changes in fibre composition. Only six cultivars were analysed by chemical fractionation methods to determine changes in lignin, cellulose and hemicellulose content. The results from the two methods of fibre analysis were broadly similar. K, Ca, Mg and Na concentrations of the treated straw samples were found to be different to the untreated samples. Increase in dry matter digestibility (DMD) of treated straw was observed for all cultivars; the effects on Beaver, Brigadier, Mercia, Riband, Genesis, Hunter and Cadenza were most pronounced, but were less for Hussar, Spark and Flame. The potential impact of these changes in straw quality on organic mushroom compost preparation is briefly discussed.