Compositional variation amongst sorghum hybrids: Effect of kafirin concentration on metabolizable energy

Kafirins are stored proteins that negatively affect the nutritional quality of sorghum grain. Kafirin concentration and other chemical characteristics were determined in 12 sorghum hybrids and varied significantly, from 58% (HB1) to 42% (HB12) as percent total protein. Kafirin concentration correlated negatively with crude protein (CP) (−0.49), with acid detergent fiber (−0.40), apparent metabolizable energy (−0.61), and true metabolizable energy corrected for N (−0.63). HB12 was the hybrid with the lowest content of kafirins, amylose and tannins, and the highest content of apparent metabolizable energy. No differences were observed in the concentration of starch, but differences were found in apparent metabolizable energy (3325–2944 kcal kg⁻¹) probably due to a greater availability of starch, related to differences in kafirin concentration.     

Production of bioethanol from steam-flaked sorghum and maize

The aim was to study the effect of steam-flaking of sorghum and maize on bioethanol production and the performance of their ground meals during liquefaction, saccharification and yeast fermentation. A bifactorial experiment with a level of confidence of P < 0.05 was designed to study differences between sorghum and maize and the effectiveness of steam-flaking. Grains were steam-flaked to increase starch bioavailability and disrupt the protein matrix that envelopes starch granules. The steam-flaked sorghum had significantly higher and faster starch hydrolysis compared to the regular kernel during liquefaction. This hydrolysate contained about 33% more reducing sugars compared to the untreated counterpart and similar amounts compared to both maize treatments. At the end of saccharification, the sorghum spent grains contained more residual starch compared to the maize counterparts. Steam-flaking significantly reduced residual starch especially in steam-flaked sorghum. The final glucose concentration in steam-flaked sorghum was similar to the concentration obtained in both maize mashes and 26.5% higher compared to the untreated sorghum. The yield of ethanol in steam-flaked sorghum was 44.2% higher compared to the untreated counterpart and similar to both maize treatments. Therefore, steam-flaking is a treatment useful to increase ethanol production especially in sorghum due to the higher starch bioavailability.     

Genetic and Environmental Variation in Sorghum Starch Properties

Starch was isolated from eight local Zimbabwean landrace varieties, an improved cultivar (SV2) and a hybrid (DC-75) of sorghum grown in four environments. Amylose content, pasting (peak (PV), hot-paste (HPV), cool-paste (CPV) viscosity), textural and thermal (gelatinisation peak temperature (T_p) and gelatinisation energy (ΔH)) properties of the starches were determined. The F -tests from analyses of variance detected significant (p<0·001) differences among genotypes and growing environments for the starch properties measured. The results indicate that a range of genetic and environmental variability exists for these traits in sorghum genotypes although the latter could be greater than varietal effects. Hybrid DC-75 largely differed in starch amylose content, pasting PV, and gel hardness from the local landrace varieties. Environments used for local landrace varieties caused significant differences in starch properties, hence selection and monitoring of growing conditions is essential if a particular genotype is to maintain minimum variation in the desired pasting, textural or thermal properties. Genotype×environment interactions indicate that in breeding programmes, selection for starch properties at a single location would be misleading.     

Differences in the functionality and characterization of kafirins extracted from decorticated sorghum flour or gluten meal treated with protease

Kafirins have been extracted from several types of sorghums due to their potential use for production of gluten-free products. Nevertheless, the extraction of these proteins from wet-milled sorghum gluten meal (SGM) has not yet been explored. In this study, we investigated the differences in composition, color, molecular structures, functionality and in vitro protein digestibility of kafirin extracts obtained from dry-milled flour or SGM obtained from decorticated white sorghum treated with and without endopeptidic protease. Kafirins were extracted using aqueous ethanol and metabisulfite. Kafirin extracts from SGM presented higher protein purity (95% vs 86%), lower fat content (0.7% vs 2.0%), in vitro protein digestibility (89% vs 85%), and better water holding (2.8 vs 1.9 g/g) and fat absorption capacities (2.4 vs 1.6 g/g) compared to extracts from ground decorticated sorghum. Color was not affected by treatments. SDS-PAGE showed differences in the low molecular weight patterns of kafirin extracts obtained from SGM whereas FTIR analyses showed reduction of α-helical and β-turn percentages and β-sheet increment after extraction. The proposed protease treatment increased free amino nitrogen and emulsifying index of kafirins, but did not affect other functional properties. Thus, SGM represents a potential new feedstock for the extraction of food-grade kafirins.     

Storage retrogradation behavior of sorghum, maize and rice starch pastes related to amylopectin fine structure

Storage retrogradation behavior and properties of sorghum, maize, and rice starches were compared to better understand the relationship of amylopectin fine structure to quality issues. Long-term changes in texture of starch gels were attributed to amylopectin retrogradation. In starch pastes aged 7 days at 4 °C, change in the storage modulus (ΔG^′) during heating (representing intermolecular associations) was highly and positively correlated (r = 0.93, p < 0.01) with the proportion of fraction I (FrI) long chains from debranched amylopectin. One sorghum cultivar, Mota Maradi, showed a dramatic increase in the storage modulus (G′) over the 7 day storage period that was related to its high proportion of FrI. Pastes/gels made from starches with normal (20–30%) amylose content and higher proportions of FrI long chains from debranched amylopectin tended to become firmer with more syneresis during extended storage. Both degree of polymerization measurements and previous models for amylopectin structure indicate that FrI represents long B chains of amylopectin. Cereal cultivars having amylopectin structures with lower proportion of long B chains were speculated to give improved quality products with lower rates of retrogradation and staling. This is particularly an issue in sorghum foods where products generally lack storage stability and tend to stale relatively quickly.     

Biomass yield and energy balance of three perennial crops for energy use in the semi-arid Mediterranean environment

Three different lignocellulosic energy crops (a local clone of Arundo donax L., Miscanthus x giganteus Greef et Deu. and Cynara cardunculus L. var. altilis D.C. cv. “Cardo gigante inerme”) were compared over 5 years (2002–2007) for crop yield, net energy yield and energy ratio. In a hilly interior area of Sicily (Italy), two different irrigation treatments (75 and 25% of ETm restoration) and two nitrogen fertilization levels (100 and 50 kg ha⁻¹) were evaluated in a split-plot experiment. In the fourth and fifth years of the field experiment (2005–2007) no fertilizer or irrigation was used.From crop establishment to the third year, above ground dry matter yield increased over all studied factors, in A. donax from 6.1 to 38.8 t ha⁻¹ and in M. x giganteus from 2.5 to 26.9 t ha⁻¹. Fifteen months after sowing, C. cardunculus yielded 24.7 t ha⁻¹ of d.m. decreasing to 8.0 t ha⁻¹ in the third year. In the fourth and fifth years, above ground dry matter yields of all crops decreased, but A. donax and M. x giganteus still maintained high productivity levels in both years. By contrast the yield of C. cardunculus yield fell to less than 1 t ha⁻¹ of d.m. by the fourth year.Energy inputs of A. donax and M. x giganteus were higher in the year of establishment than that of C. cardunculus (34 GJ ha⁻¹ for A. donax and M. x giganteus and 12 GJ ha⁻¹ for C. cardunculus), mainly due to irrigation.Net energy yield showed low or negative values in the establishment year in A. donax and M. x giganteus. In the second and third year, net energy yield of A. donax was exceptionally high (487.2 and 611.5 GJ ha⁻¹, respectively), whilst M x giganteus had lower values (232.2 and 425.9 GJ ha⁻¹, respectively). M x giganteus attained its highest net energy yield in the fourth year (447.2 GJ ha⁻¹). Net energy yield of C. cardunculus reflected energy output of the crop, being high in the first compared to subsequent years (364.7, 277.0 and 119.2 GJ ha⁻¹, respectively for the first, second and third years).A significant effect of the different irrigation treatments was noted on all the studied parameters in all species. Conversely, only A. donax was affected by nitrogen fertilization.     

Wet-milling Factors of Sorghum and Relationship to Grain Quality

Relationships of grain sorghum quality factors (proximate composition and physical properties) to laboratory wet-milling attributes (fraction yields, protein content of fractions and recovery values) of 24 grain sorghum commercial hybrids were determined. Initial water absorption rate was positively correlated with both starch and gluten recoveries (r>0·45), thus showing the greatest significance among all quality factors. The need to understand fully protein matrix breakdown relative to obtaining optimum separation of components was indicated. Positive correlations of residual protein in starch with density and percent abraded (r>0·45) were observed. Laboratory wet-milling attributes also were correlated among themselves. The highest positive correlations were observed among yield and recovery of starch and gluten (r>0·6). These four parameters had strong negative correlations with fiber/germ yield (r<−0·6). Principal component factor analysis identified five factors (named as matrix-breakdown effect, solids-leaching effect, protein-dispersion effect, protein content of gluten effect, and washing-solids effect) that explained 91% of the total variation among wet-milling attributes.     

Grain concentrations of protein and mineral nutrients in a large collection of spelt wheat grown under different environments

A large number of spelt wheat genotypes (ranging from 373 to 772) were evaluated for grain concentrations of protein and mineral nutrients under 6 different environments. There was a substantial genotypic variation for the concentration of mineral nutrients in grain and also for the total amount of nutrients per grain (e.g., content). Zinc (Zn) showed the largest genotypic variation both in concentration (ranging from 19 to 145 mg kg⁻¹) and content (ranging from 0.4 to 4.1 μg per grain). The environment effect was the most important source of variation for grain protein concentration (GPC) and for many mineral nutrients, explaining between 37 and 69% of the total sums of squares. Genotype by environment (G × E) interaction accounted for between 17 and 58% of the total variation across the minerals. GPC and sulfur correlated very significantly with iron (Fe) and Zn. Various spelt genotypes have been identified containing very high grain concentrations of Zn (up to 70 mg kg⁻¹), Fe (up to 60 mg kg⁻¹) and protein (up to 30%) and showing high stability across various environments. The results indicated that spelt is a highly promising source of genetic diversity for grain protein and mineral nutrients, particularly for Zn and Fe.     

Effect of particle size on kinetics of starch digestion in milled barley and sorghum grains by porcine alpha-amylase

The influence of milled grain particle size on the kinetics of enzymatic starch digestion was examined. Two types of cereals (barley and sorghum) were ground, and the resulting grounds separated by size using sieving, with sizes ranging from 0.1 to 3 mm. In vitro enzymatic digestion was performed, using pancreatic alpha-amylase, amyloglucosidase and protease, to determine fractional-digestion rates over 24 h. The resulting glucose production rate data were well fitted by simple first-order kinetics. For each sieve screen size, the digestion rate of barley was always higher than that of sorghum. The rate coefficients for digestion showed a decrease with increasing size, and could be well fitted by an inverse square relationship. This is consistent with the supposition that starch digestion in these systems is controlled by diffusion of enzyme through the grain fragment. Apparent diffusion coefficients of alpha-amylase obtained by fitting the size dependence were 0.76 (sorghum) and 1.7 (barley) × 10⁻⁷ cm² s⁻¹, 9 (sorghum) and 4 (barley) times slower than predicted for a molecule of the size of alpha-amylase in water.     

Particle size heterogeneity in milled barley and sorghum grains: Effects on physico-chemical properties and starch digestibility

The average particle size of ground grains is known to influence properties related to processing (e.g. water absorption and solubility) and nutritional value (e.g. starch digestion rate) of human foods and animal feeds. The purpose of this study was to identify the contributions made by individual size fractions of hammer-milled barley and sorghum grains to average bulk compositional, hydration, rheological, and enzyme susceptibility properties. Barley and sorghum grains were each hammer-milled through a 4 mm screen and subsequently fractionated on a set of eight sieves ranging from 0.125 mm to 2.8 mm. Individual fractions were characterised for (1) starch, aNDF, and water content, (2) water absorption index (WAI) and water solubility index (WSI), (3) viscosity profile during cooking and cooling in excess water, and (4) in vitro starch digestibility. Weighted average values based on fraction yields and property values for WAI, WSI, and starch digestibility were not significantly different from values obtained for non-fractionated ground grains of both barley and sorghum. Glucose yields from starch digestion varied about ten-fold between the smallest and largest particle fractions, and WAI and WSI had value ranges of 1.9–2.8 g/g (sorghum), 2.1–4.0 g/g (barley) and 1.3–4.5% (sorghum), 0.7–10.3% (barley), respectively. Viscosity profiles for milled sorghum grain fractions were dominated by starch swelling which became increasingly restricted as particle sizes increased. Viscosity profiles for milled barley grain fractions did not exhibit typical starch-based behaviour and were most likely dominated by soluble fibres. Taken together, the results show that there is considerable potential for designing combinations of hydration, rheological and digestibility properties of ground grains through informed selection of appropriate grains and particle size distributions.     

Valorization of three varieties of grape

In the present investigation, seed methanolic extracts of three Vitis vinifera (Muscat d’Italie, Syrah and Carignan) were assayed for their antioxidant activities. Results showed that there are strong variations in the contents of total phenols (440.97–121.94 mg GAE g⁻¹ DW), flavonoids (48.07–16.81 mg EC g⁻¹ DW) and tanins (37.15–14.9 mg EC g⁻¹ DW) from the studied seeds. The phenolic composition of these extracts was determined by RP–HPLC after acid hydrolysis. The main phenolic compound was quercetin with 27.2% in Muscat d’Italie, 48.8% in Syrah and 28.4% in Carignan. Besides, all seed extracts showed remarkable DPPH radical scavenging activity with IC₅₀ values ranged from 1.8 to 30 μg ml⁻¹. EC₅₀ values of reducing power activity ranged from 100 to 120 μg ml⁻¹. The high phenolic content and the considerable antioxidant activities of vitis seed extracts could potentially be considered as an expensive source of natural antioxidants.     

Phosphorus accumulation and depletion in soils in wheat–maize cropping systems: Modeling and validation

Long-term (over 15 years) winter wheat (Triticum aestivum L.)–maize (Zea mays L.) crop rotation experiments were conducted to investigate the accumulation of phosphorus (P) at five sites differing geographically and climatically in China. The results showed that, in soils without P added, the concentration of soil P extracted by 0.5 mol L⁻¹ NaHCO₃ at pH 8.5 (Olsen-P) decreased with cultivation time until about 3 mg kg⁻¹, afterwards it remained constant. The trend of decrease in Olsen-P in soils without P added could be described by an exponential function of time. The concentration of Olsen-P in soils with P fertilizers increased with cultivation time and the model of accumulation of Olsen-P in soils could be described using P application rate, crop yield and soil pH. The accumulation rate of Olsen-P in the long-term wheat–maize crop rotation experiments was 1.21 mg kg⁻¹ year⁻¹ on average. If the target yield of wheat and maize is 10 ton ha⁻¹ in the soil with pH 8, the increasing rates of Olsen-P in soils as estimated by the model will be 0.06, 0.36, 0.66, 0.95, 1.25 and 1.55 mg kg⁻¹ year⁻¹ when P application rates are 30, 40, 50, 60, 70 and 80 kg P ha⁻¹ year⁻¹, respectively. The models of accumulation of Olsen-P in soils were validated independently and could be used for the accurate prediction of accumulation rate of Olsen-P in soils with wheat–maize rotation systems. Also the application of the model was discussed for best management of soil P in agricultural production and environment protection.     

Long-term effects of poultry litter and conservation tillage on crop yields and soil phosphorus in cotton–cotton–corn rotation

Long-term field experiments are needed to fully realize positive and negative impacts of conservation tillage and poultry litter application. A study was initiated on a Decatur silt loam soil at the Tennessee Valley Research and Extension Center, Belle Mina, AL, USA in 1996 to evaluate cotton (Gossypium hirsutum L.) performance with long-term poultry litter (PL) application under different tillages and to study the build up of phosphorus (P) with application of PL. Treatments include incomplete factorial combinations of three tillage systems [conventional till (CT), mulch till (MT), and no-till (NT)], two cropping systems [cotton-fallow and cotton-winter rye (Secale cereale L.)], and two nitrogen sources and rates [100 kg N ha⁻¹ from ammonium nitrate (AN), and 100 and 200 kg N ha⁻¹ from poultry litter (PL)]. Cotton was rotated with corn (Zea mays L.) every third year. Results from 2003 to 2008 showed that all tillages gave similar cotton lint yields with AN at 100 kg N ha⁻¹. Application of PL at 100 kg N ha⁻¹ in NT plots resulted in 12 and 11% yield reductions compared to that of CT and MT, respectively. However, NT plots with higher quantity of PL (200 kg N ha⁻¹) gave similar yields to CT and MT at 100 kg N ha⁻¹. During corn years, higher residual fertility of PL, in terms of grain yields, was observed in NT plots compared to CT and MT. Long-term PL application (100 kg N ha⁻¹ year⁻¹) helped to maintain original soil pH in CT and MT while AN application decreased soil pH. In NT plots, PL at 100 kg N ha⁻¹ was not sufficient to maintain original soil pH, but 200 kg N ha⁻¹ maintained original pH. Although not-significant, elevated P levels were observed in all tillages compared to original P levels which indicates possibility of P build up in future with further application of PL. Application of PL at double rate (200 kg N ha⁻¹) in NT plots resulted in significant build up of P. Results indicate that NT gives similar yields to CT when received AN, but needs higher rate of PL application to achieve similar yields to CT.     

Small-scale mashing procedure for predicting ethanol yield of sorghum grain

A small-scale mashing (SSM) procedure requiring only 300 mg of samples was investigated as a possible method of predicting ethanol yield of sorghum grain. The initial SSM procedure, which was conducted similarly to the mashing step in a traditional fermentation test, hydrolyzed just 38.5–47.2% of total sorghum starch to glucose. The initial procedure was simplified to contain only one liquefaction step, which did not influence subsequent saccharification. Thereafter, parameters such as temperature, pH, enzyme dosage, and saccharification time were optimized. Results showed that 91.2–97.5% of the total starch in 18 sorghum hybrids had been hydrolyzed to glucose using the following conditions: liquefaction at 86 °C for 90 min, 20 μL of α-amylase per 30 g of sample; pH adjustment by adding 50 μL of 2 M acetate buffer at pH 4.2 to each microtube; saccharification at 68 °C for 90 min, 200 μL of amyloglucosidase per 30 g of sample. There were strong linear correlations between completely hydrolyzed starch (CHS) from SSM and ethanol yields from both traditional (R² = 0.86) and simultaneous saccharification and fermentation (SSF, R² = 0.93) procedures. CHS was a better indicator for predicting ethanol yield in fermentation than total starch.     

Forage soybean production for seed in mediterranean environments

Despite several experiments on row spacings and seeding rates of grain soybeans, limited information is available on the most suitable row spacing and seeding rate for tall and robust forage type soybeans grown for seed. The objectives of this study were to investigate seed yield, oil and protein content, and several morphological traits as affected by row spacing (20, 40, 60 and 80 cm) and seeding rate (330,000, 660,000, 990,000 and 1,320,000 seeds ha⁻¹) in tall and robust forage type soybeans in three irrigated Mediterranean environments in Turkey in a randomized split plot design with three replications in 2004 and 2005. Row spacings had no significant effect on plant height but tall and profusely branched plants developed in wide row spacing and light seeding conditions. Seed yield responded positively and linearly to row spacing up to 60 cm and then decreased slightly in all locations. Seed yield was the highest at 990,000 seeds ha⁻¹ seeding rate in all three locations (3072.5 kg ha⁻¹ in Bursa LSD = 214.7 kg ha⁻¹, 3295.1 kg ha⁻¹ in Mustafakemalpasa LSD = 298.6 kg ha⁻¹ and 3311.3 kg ha⁻¹ in Samsun LSD = 321.1 kg ha⁻¹). Averaged across years, locations, row spacings, and seeding rates the mean seed yield was an impressive 3013.4 kg ha⁻¹ compare with 3500.0 kg ha⁻¹ average seed yield of grain types. Crude protein and oil content of forage type soybean were not significantly affected by row spacings and seeding rates. It was concluded that forage type soybeans can be grown for multiple purposes at the 990,000 seeds ha⁻¹ seeding rate and 60 cm row spacings in Mediterranean environments.     

Predicted truly absorbed protein supply to dairy cattle from hulless barley (Hordeum vulgare L.) with altered carbohydrate traits with multi-year samples

Hulless barley breeding lines varying in amylose (1–20% DM) and β-glucan content (5–10% DM) have been developed at the Crop Development Centre, Canada. The objectives of this large-scale study were to 1) determine and confirm the effect of these new hulless barley lines (zero-amylose waxy, CDC Fibar; 5%-amylose waxy, CDC Rattan; normal-amylose, CDC McGwire and high-amylose, HB08302) with altered carbohydrate traits on 1) metabolic characteristics of protein; 2) intestinal digestion of various nutrients and 3) modeling nutrient supply from these barley varieties by using NRC Dairy 2001 model and DVE/OEB system. CDC Copeland was included as a hulled barley control. Among the hulless barley lines, CDC Fibar contained the highest and CDC McGwire contained the lowest total digestible protein (TDP: 147 vs. 116 g/kg DM). HB08302 was greater (P < 0.05) in intestinal digestible protein (IDP: 40.6% RUP) but relatively lower (P < 0.05) in total digestible protein (TDP: 120 g/kg DM). Compared with hulless barley, hulled barley showed relatively lower (P < 0.05) intestinal digestible protein (38 vs. 53 g/kg DM) and total digestible protein (102 vs. 129 g/kg DM). In modeling nutrient supply from the DVE/OEB system, the results showed hulled barley was lower (P < 0.01) in true protein supplied to the small intestine (TPSI: 127 vs. 142 g/kg DM), lower in truly absorbed rumen bypassed feed protein in small intestine (ABCP^DVE: 43 vs. 58 g/kg DM), lower in truly absorbed protein in the small intestine (DVE: 95 vs. 111 g/kg DM), and lower in degraded protein balance (OEB^DVE: −39 vs. −23 g/kg DM) than the hulless barley lines but greater (P < 0.01) in undigested inorganic matter (9 g/kg DM). From NRC Dairy 2001 model, CDC Fibar was greater (P < 0.05) in degraded protein balance (OEB^NRC: −30 g/kg DM) and metabolizable protein (MP: 118 g/kg DM) than the other hulless barley lines, while hulled barley was relatively lower (P < 0.01) in total metabolizable protein (MP: 83 vs. 105 g/kg DM). Our correlation results suggested that TDP was negatively correlated to amylose (r = −0.85, P < 0.001) but positively correlated to β-glucan level (r = 0.74, P < 0.001) in hulless barley cultivars. The DVE and OEB^DVE as well as MP were negatively correlated (P < 0.05) to amylose level but positively correlated to β-glucan level (P < 0.05). In conclusion, altered carbohydrate traits in the hulless barley varieties have the potential to increase intestinal nutrient availability to ruminants and significantly improved the truly absorbed protein supply to dairy cattle compared to hulled barley. Hulless barley with lower amylose and higher β-glucan level could provide greater (P < 0.05) truly digested protein in the small intestine, better synchronized available energy and N and increase metabolizable protein supply to ruminants.     

Predicted truly absorbed protein supply to dairy cattle from hulless barley (Hordeum vulgare L.) with altered carbohydrate traits with multi-year samples

Hulless barley breeding lines varying in amylose (1–20% DM) and β-glucan content (5–10% DM) have been developed at the Crop Development Centre, Canada. The objectives of this large-scale study were to 1) determine and confirm the effect of these new hulless barley lines (zero-amylose waxy, CDC Fibar; 5%-amylose waxy, CDC Rattan; normal-amylose, CDC McGwire and high-amylose, HB08302) with altered carbohydrate traits on 1) metabolic characteristics of protein; 2) intestinal digestion of various nutrients and 3) modeling nutrient supply from these barley varieties by using NRC Dairy 2001 model and DVE/OEB system. CDC Copeland was included as a hulled barley control. Among the hulless barley lines, CDC Fibar contained the highest and CDC McGwire contained the lowest total digestible protein (TDP: 147 vs. 116 g/kg DM). HB08302 was greater (P < 0.05) in intestinal digestible protein (IDP: 40.6% RUP) but relatively lower (P < 0.05) in total digestible protein (TDP: 120 g/kg DM). Compared with hulless barley, hulled barley showed relatively lower (P < 0.05) intestinal digestible protein (38 vs. 53 g/kg DM) and total digestible protein (102 vs. 129 g/kg DM). In modeling nutrient supply from the DVE/OEB system, the results showed hulled barley was lower (P < 0.01) in true protein supplied to the small intestine (TPSI: 127 vs. 142 g/kg DM), lower in truly absorbed rumen bypassed feed protein in small intestine (ABCP^DVE: 43 vs. 58 g/kg DM), lower in truly absorbed protein in the small intestine (DVE: 95 vs. 111 g/kg DM), and lower in degraded protein balance (OEB^DVE: −39 vs. −23 g/kg DM) than the hulless barley lines but greater (P < 0.01) in undigested inorganic matter (9 g/kg DM). From NRC Dairy 2001 model, CDC Fibar was greater (P < 0.05) in degraded protein balance (OEB^NRC: −30 g/kg DM) and metabolizable protein (MP: 118 g/kg DM) than the other hulless barley lines, while hulled barley was relatively lower (P < 0.01) in total metabolizable protein (MP: 83 vs. 105 g/kg DM). Our correlation results suggested that TDP was negatively correlated to amylose (r = −0.85, P < 0.001) but positively correlated to β-glucan level (r = 0.74, P < 0.001) in hulless barley cultivars. The DVE and OEB^DVE as well as MP were negatively correlated (P < 0.05) to amylose level but positively correlated to β-glucan level (P < 0.05). In conclusion, altered carbohydrate traits in the hulless barley varieties have the potential to increase intestinal nutrient availability to ruminants and significantly improved the truly absorbed protein supply to dairy cattle compared to hulled barley. Hulless barley with lower amylose and higher β-glucan level could provide greater (P < 0.05) truly digested protein in the small intestine, better synchronized available energy and N and increase metabolizable protein supply to ruminants.     

Growth, yield and mineral content of Miscanthus × giganteus grown as a biofuel for 14 successive harvests

Miscanthus × giganteus, a perennial rhizomatous grass commercially used as a biofuel crop was grown in a field experiment on a silty clay loam soil for 14 years. There were 3 rates of fertilizer nitrogen (N), none (control), 60 kg N ha⁻¹ yr⁻¹ and 120 kg N ha⁻¹ yr⁻¹ as cumulative applications. The crop was harvested in winter and dry matter yield measured. N did not influence yield. Yield, which increased for the first 6 years, decreased in years 7 and 8, but then increased again and was highest in the 10th year averaging 17.7 t ha⁻¹ across all treatments. Differences in total production over the14 years were only 5% between the highest and lowest yielding treatments and averaged 178.9 t ha⁻¹ equivalent to 12.8 t ha⁻¹ yr⁻¹. In the first 10 harvests, 92% of dry matter was stem. Although the study showed N fertilizer was not required, it is considered that an application of 7 kg P ha⁻¹ yr⁻¹ and 100 kg K ha⁻¹ yr⁻¹ would avoid soil reserve depletion. Pesticides were not required every year and the crop can be considered as low input with a high level of sustainability for at least 14 years.     

In vitro starch digestibility and predicted glycaemic indexes of buckwheat,oat, quinoa,sorghum, teff and commercial gluten-free bread

The in vitro starch digestibility of five gluten-free breads (from buckwheat, oat, quinoa, sorghum or teff flour) was analysed using a multi-enzyme dialysis system. Hydrolysis indexes (HI) and predicted glycaemic indexes (pGI) were calculated from the area under the curve (AUC; g RSR/100g TAC*min) of reducing sugars released (RSR), and related to that of white wheat bread. Total available carbohydrates (TAC; mg/4 g bread “as eaten”) were highest in sorghum (1634 mg) and oat bread (1384 mg). The AUC was highest for quinoa (3260 g RSR), followed by buckwheat (2377 g RSR) and teff bread (2026 g RSR). Quinoa bread showed highest predicted GI (95). GIs of buckwheat (GI 80), teff (74), sorghum (72) and oat (71) breads were significantly lower. Significantly higher gelatinization temperatures in teff (71 °C) and sorghum flour (69 °C) as determined by differential scanning calorimetry (DSC) correlated with lower pGIs (74 and 72). Larger granule diameters in oat (3–10 μm) and sorghum (6–18 μm) in comparison to quinoa (1.3 μm) and buckwheat flour (3–7 μm) as assessed with scanning electron microscopy resulted in lower specific surface area of starch granules. The data is in agreement with predictions that smaller starch granules result in a higher GI.     

In vitro starch digestibility and predicted glycaemic indexes of buckwheat,oat, quinoa,sorghum, teff and commercial gluten-free bread

The in vitro starch digestibility of five gluten-free breads (from buckwheat, oat, quinoa, sorghum or teff flour) was analysed using a multi-enzyme dialysis system. Hydrolysis indexes (HI) and predicted glycaemic indexes (pGI) were calculated from the area under the curve (AUC; g RSR/100g TAC*min) of reducing sugars released (RSR), and related to that of white wheat bread. Total available carbohydrates (TAC; mg/4 g bread “as eaten”) were highest in sorghum (1634 mg) and oat bread (1384 mg). The AUC was highest for quinoa (3260 g RSR), followed by buckwheat (2377 g RSR) and teff bread (2026 g RSR). Quinoa bread showed highest predicted GI (95). GIs of buckwheat (GI 80), teff (74), sorghum (72) and oat (71) breads were significantly lower. Significantly higher gelatinization temperatures in teff (71 °C) and sorghum flour (69 °C) as determined by differential scanning calorimetry (DSC) correlated with lower pGIs (74 and 72). Larger granule diameters in oat (3–10 μm) and sorghum (6–18 μm) in comparison to quinoa (1.3 μm) and buckwheat flour (3–7 μm) as assessed with scanning electron microscopy resulted in lower specific surface area of starch granules. The data is in agreement with predictions that smaller starch granules result in a higher GI.