Digestibility Of Maize Research Articles

Hydrothermal carbonisation of manure-derived digestates: Chemical properties and heavy metals distribution in end-products

Hydrothermal carbonisation (HTC) presents a promising method for converting high-moisture biomass into hydrochars, which can serve as valuable sources of carbon and nutrients for soil applications. However, there is a lack of comprehensive understanding regarding the characterisation and potential environmental risks of hydrochars with respect to different feedstock types and operating conditions especially when compared to those obtained from dry pyrolysis. This research aims to investigate the chemical properties and re-partitioning of Ni, Cd, Cr and Pb in the HTC-treated mono-and co-digestates derived from the anaerobic digestion of pig manure and ensiled maize. Hydrochars were produced from homogeneous digestate slurries, where manure was derived from a unique source separation facility, and maize was collected from a contaminated land, both containing potentially higher concentrations of heavy metals (HMs) compared to typical feedstock. The hypothesis states that HTC would further reduce the potential availability of these metals, enhancing the quality of the end-products as bio-based fertilisers or soil improvers. The derived hydrochars were analysed for their composition and HMs extractability. Higher yields were observed for both digestates at lower temperatures and shorter residence times, whereas the total nitrogen and carbon content showed an opposite trend. The composition of the digestates and the HTC operating parameters influenced the enrichment of nutrients and release of the HMs from the hydrochars, enabling their classification as potential solid organic fertilisers according to the Fertilising Products Regulation (EU) 2019/1009. Notably, the HTC treatment at 200–220 °C for 4 h resulted in the highest immobilization of Ni, Cd, Cr, and Pb in both digestates. This treatment strategy effectively reduced the ecological risk index of these products, thereby mitigating potential environmental impacts associated with the HMs contamination.

Anaerobic Digestion of Spoiled Maize, Lucerne and Barley Silage Mixture with and without Cow Manure: Methane Yields and Kinetic Studies

The effect of different inoculum-to-substrate ratios (ISRs) and feed mix (FM) ratios on the kinetics of methane production and yields during anaerobic digestion of spoiled silage mixture (SM) alone or co-digestion with cow manure (CM) was investigated in batch experiments at 37 °C. The silage mixture was prepared from spoiled silages of maize, lucerne and barley in equal proportions of 33% by wet weight. The effect of ISRs of 0.5, 1, 2 and 4 showed that methane yields increased with an increased ISR ratio. At ISRs of 1, 2 and 4, methane yields of 262.18 ± 14.96, 387.77 ± 14.43 and 482.23 ± 38.47 NmL CH4/gVSadded were obtained, respectively. Incubation at ISR 0.5 resulted in low methane yields (174.49 ± 9.29 NmL CH4/gVSadded) due to build-up of volatile fatty acids (VFAs). Further, co-digestion of spoiled SM with CM showed that the highest methane yields of 387.77 and 382.86 NmL CH4/gVSadded were obtained at SM:CM feed mix ratios of 100–0 and 75–25, respectively. The corresponding volatile solids (VS) removal rates were 72.80% and 70.82%, respectively. However, the best synergistic effect was noticed at a SM:CM = 50–50 feed mix ratio. Thus, this study shows that anaerobic digestion of spoiled silages is feasible and co-digestion of spoiled silage mixed with cow manure at a SM:CM feed mix ratio of 75–25 is recommended.

Effects on <i>in vitro</i> digestibility and rumen fermentation of maize straw silage as a partial dietary replacement for Napier grass

Effects on <i>in vitro</i> digestibility and rumen fermentation of maize straw silage as a partial dietary replacement for Napier grass

Proximate principles and dry matter digestibility of fodder maize and sugargraze in response to potassium management

The study was carried out to evaluate the forage quality of maize and sugargraze as influenced by different potassium management practices. The experiment was laid out in split-plot design in which two fodder crops, viz. maize and sugargraze, were taken as the main plot, and different potassium management regimes were taken as a subplot. Results revealed that the quality parameters of sugargraze and fodder maize crops, viz. Dry matter, crude protein, ether extract, ash content, neutral detergent fibre, acid detergent fibre, and acid detergent lignin were significantly influenced favourably by potassium management. Comparing the quality parameters, remarkably highest CP (9.70%), total ash content (9.87%) as well as potassium uptake (230 kg/ha) were obtained with 50 kg K2O + KSB + 2% KNO3 foliar spray; however, higher ether extract (1.73%) was recorded in 50 kg K2O + KSB + 2% K2SO4 foliar spray. The fibre fractions, viz. NDF (66.1%), ADF (35.4%) and ADL (4.70%) recorded considerably lower values with 25 kg K2O + KSB + 2% KNO3 foliar spray over control. The higher values of TDN (59.3%), DMD (63.6 g/kg), RFV (94.7%) and DMI (1.92 g/kg) were recorded in fodder maize over sugargraze with an application of 25 kg K2O + KSB + 2% KNO3 foliar spray. Therefore, considering all the studied parameters, it can be concluded that getting higher quality green biomass production of fodder maize and sugargraze with the application of 25 kg K2O + KSB + 2% KNO3 would be a more feasible agro-practice.

P14. Porcine in vitro digestion and fermentation characteristics of maize and wheat with or without fibre degrading enzymes

P14. Porcine in vitro digestion and fermentation characteristics of maize and wheat with or without fibre degrading enzymes

Effect of genetically modified maize expressing the Cry1Ab and EPSPS proteins on growth, development, and gut bacterial diversity of the non-target arthropod Locusta migratoria.

The widespread cultivation of genetically modified (GM) crops has raised concerns for their safety. Here, we evaluated the effects of a GM maize variety expressing the Cry1Ab (14.76 ± 0.87μg/g FW) and EPSPS proteins (191.55 ± 15.69μg/g FW) on the life-history traits and gut bacterial community of a non-target arthropod, Locusta migratoria, in the laboratory. We found that GM maize had no significant effect on the survival or body weight of different development stages of L. migratoria. The midgut and hindgut bacterial diversities and compositions were determined using high-throughput sequencing targeting the V3-V4 regions of the 16S rRNA. No significant changes were found in the species diversity or abundance between insects in the GM-fed treatment and the non-GM control. Furthermore, the concentration of Cry1Ab and EPSPS in the gut was determined after digestion of GM maize. Results showed that the contents of Cry1Ab/EPSPS rapidly decreased and were hard to detect after 72h. Based on the parameters assessed, we can conclude that the GM maize variety examined has no significant adverse effect on L. migratoria.

The importance of particle size on organic matter and crude protein in vitro digestibility of maize and soybean meal

Particle size plays an important role in the digestibility of nutrients by animals. Methodologies developed to simulate the digestive system to determine digestibility values require the grinding of samples to pass a specific sieve size (e.g. 1 mm) before in vitro digestion. The objective of this study was to evaluate if particle size affects in vitro (ileal) digestibility values of organic matter (OM) and crude protein (CP) in maize and soybean meal (SBM). Both ingredients were ground in a laboratory mill over four screens (1.50, 1.00, 0.75 and 0.50 mm) with trapezoidal holes in a sequential manner from large to fine. Particle size distribution, nutrient content and in vitro digestibility were determined of the various samples. With decreasing screen size, geometric mean diameter of particles significantly decreased from 351.4 to 203.2 µm for maize, and from 239.1 to 99.1 µm for SBM. Ash, CP and starch content were not affected whereas the neutral detergent fibre in maize and dry matter content in SBM differed after grinding with various sized screens (P < 0.05). The in vitro digestibility of OM and CP of maize and CP of SBM ground over the four different screens did not differ (P > 0.185). The OM in vitro digestibility differed (P < 0.05) with values for SBM ground over the 1.50 mm screen being lower (P < 0.05) than the smaller screen sizes: 0.814 (1.50 mm) vs 0.833 (1.00 mm), 0.829 (0.75 mm) and 0.834 (0.50 mm), respectively. Based on the current work and literature data, particles ≥ 595 µm of comminuted maize and SBM affect OM and CP in vitro digestibility. Analysis of three feeds and 10 feed ingredients ground over a 1.0 mm sieve showed that the fraction ≥ 595 µm can make up to 32.1% of the mass. It is recommended that before in vitro digestibility determination, particle size distribution is assessed, especially the mass fraction of particles ≥ 595 µm and further grinding is conducted to ensure that particles are < 595 µm for maize and SBM. The cut off size where particles size affects OM and CP in vitro (ileal) digestibility of other feeds or feed ingredients than maize and SBM should be determined.

High throughput accurate method for estimating in vitro dry matter digestibility of maize silage

BackgroundSince the introduction of studies on maize silage digestibility at the end of the nineteenth century, protocols to estimate dry matter digestibility have not stopped evolving. Since the early 1980s, the protocol developed by Aufrère became a benchmark in many laboratories to estimate in vitro dry matter digestibility. In order to increase its throughput, to facilitate its execution and to decipher the impact of the different parameters of the protocol we decided to test the combination of 7 parameters in 21 different protocols.ResultsWe thus tested the impact of (1) the presence or absence of pepsin in HCl solution, (2) the temperature of incubation during enzymatic hydrolysis, (3) the presence or absence of a gelatinization step, (4) washing/rinsing versus neutralization step, (5) the presence or absence of α-amyloglucosidase in enzymatic solution, (6) the duration of cellulase incubation, and (7) the concentration of the cellulase solution. The major result of our work highlighted that it was essential to carry out a gelatinization step to correctly estimate the in vitro dry matter digestibility of maize silage.ConclusionsThe proposed protocol in this paper is innovative, reliable, highthroughput and easy to implement in many laboratories to accurately quantity in vitro dry matter digestibility.

Comparison of methodologies to determine the apparent ileal amino acid digestibility of maize, wheat, lupins, and peas for broiler chickens

The influence of method (direct vs difference method) used to determine the apparent ileal digestibility coefficient (AIDC) of amino acids in two cereals (maize and wheat) and two grain legumes (Australian sweet lupins and peas) was investigated. For the direct method, the test ingredients were incorporated as the sole source of protein in assay diets. The assay diets used in the difference method were formulated by substituting the cereals and legumes for 50 and 25% (w/w), respectively, of a maize-soy basal diet. Each diet contained 3 g/kg titanium dioxide as an indigestible marker and were offered ad libitum to four replicate cages of broilers (four birds/cage) from d 28 to d 35 post-hatching. On d 35, digesta were collected from the terminal ileum and the AIDC of amino acids were calculated using marker ratios in the diet and digesta. Except for histidine, methionine, cysteine and tyrosine, the main effect of methods was found to be significant (P&lt;0.05 to 0.001) for the AIDC of all amino acids. The main effect of the ingredients was significant (P&lt;0.05 to 0.001) for all amino acids, except for histidine, aspartic acid and serine. Interactions (P&lt;0.05) between ingredients and method were observed only for leucine, lysine, proline and serine. The AIDC of amino acids, determined by the difference method, was found to be distinctly higher than those determined by the direct method. This suggested that the direct method underestimated amino acid digestibility in low and medium protein ingredients.

Heteroscedasticity analysis of nixtamalization effect on nutrients, digestibility, and functional properties of quality protein maize and indigenous local maize flour

This study investigates the variability of nutrients, digestibility, and functional properties of two varieties of maize—Indigenous Local maize (ILM) and Quality Protein Maize (QPM) processed into traditional and nixtamalized flour. Crude protein, lysine, available lysine, niacin content, in vitro protein digestibility, in vitro starch digestibility, and functional properties data obtained were subjected to descriptive statistics, correlation, and general linear model analyses. Results indicated that crude protein was highest (9.047 g/100 g) in traditional QPM flour, while lysine, available lysine, and Niacin were highest in nixtamalized QPM flour. General linear model analysis indicated that the type of treatment significantly affected the mean content of crude protein, lysine, available lysine, and niacin. The F(3,4:0.05) = 16.333, 809.90, 58.48, and 229.72 garnered, respectively, for bulk density, water absorption capacity, oil absorption capacity, and least gelation concentration of the processed maize sample were significant (p < .01). Nixtamalization as a processing technology could be harnessed for good quality maize flour development in terms of nutrients availability, digestibility, and functional properties. Practical applications The practical application of this study is that knowledge of the variability of nixtamalized maize flour sample is essential for food product development, food control, and standardization. Also, the variability of the nixtamalized maize flour sample enhances processors/industrialists’ knowledge and preference over the traditional maize flour processing as well as consumers’ acceptability/and preference to the earlier known maize flour sample.

Biomass yield, chemical composition and in vitro digestibility of maize leaves defoliated at different times

This experiment was conducted to determine the effect of defoliation time on the productivity of maize, forage and in vitro digestibility of maize leaves (ML). The response of grain yield, plant height, days to 50% silking, ear height and leaf yield as well as the chemical composition of ML variety "Obasuper" to defoliation time were evaluated in a randomized complete block design with four defoliation treatments 3, 6, 9 weeks after planting (WAP) and undefoliated treatment replicated four times. Results showed that defoliating maize at 9 WAP and beyond did not have any significant (P&gt;0.05) effect on the grain and leaf yield as well as other yield components of maize. Grain and leaf yield at 9 WAP averaged 2778.35 and 975.74 DM kg/ha respectively. The DM, crude protein (CP) and fibre fractions contents of ML varied significantly (P&lt;0.05) among the defoliation treatments with maize defoliated at 9 WAP having a CP content of 12.6%. Ether extract and ash contents were not affected (P&gt;0.05) by defoliation time. The in vitro digestibility of ML decreased significantly (P&lt;0.05) with increase in the time of defoliation ranging from 59.2 and 66.4%. IT was concluded that maize variety "Obasuper" can produce forage of high quality and quantity when defoliated 9 weeks after planting wihout any anyadverse effect on the grain yield of maize.

Effect of Lactic Acid Bacteria on the Nutritive Value and In Vitro Ruminal Digestibility of Maize and Rice Straw Silage

A study was conducted to determine the effects of lactic acid bacteria (LAB) on nutritive value and in vitro rumen digestibility of maize and rice straw silages. Two identical experiments were carried out for each of the two silages. A total of five treatments were used for each experiment: (1) negative control (NC); (2) positive control (PC); (3) Lactobacillus plantarum (LPL); (4) L. paracasei (LPA); and (5) L. acidophilus (LA). Each treatment was then divided into four ensiling periods: 3, 7, 20, and 40 days with three replications. The LPL treatment had significantly higher dry matter (DM), lower ammonia-N, and a lower number of fungi on maize silage after 40 days (p &lt; 0.05). On the other hand, the LA treatment increased DM and CP content, reduced NDF and ADF contents compared to NC, and also produced more lactic acid compared to the other LAB-treated rice straw silages. Results of the in vitro rumen fermentation of maize silages showed no significant differences in DMD after LAB inoculation. However, higher DMD and ruminal ammonia-N were shown by rice straw ensiled with L. acidophilus. In conclusion, silage additives, which could improve the ensiling process of maize and rice straw, appeared to be different and substrate specific.

STANDARDISED ILEAL AMINO ACID DIGESTIBILITY OF SELECTED FEEDSTUFFS IN BROILER CHICKEN

Standardised Ileal Amino Acid Digestibility (SIAAD) of maize, wheat, soybean meal (SM), groundnut cake (GC) and rice bran (RB) in broiler finisher diets was investigated. Three hundred and sixty 35-day old Arbor Acre broiler chicks were randomly allotted to a Nitrogen-Free Diet (NFD) and five semi-purified diets containing each of the test feedstuffs (maize, wheat, SM, GC and RB) as the sole source of protein. Diets were fed to ten birds of six replicates up to day-42 in a randomised complete block design. Chromic oxide (5 g/kg) was added to the feed as an indigestible dietary marker. Six birds per replicate were asphyxiated with CO2 and digesta samples were collected from terminal ileum on day 42. The endogenous amino acid losses (EAAL), apparent ileal amino acid digestibility (AIAAD) and SIAAD were estimated. Highest EAAL concentration was found in threonine (0.29g/kg), while glutamic acid and alanine (0.03g/kg) had the least. Total AIAAD were 69.47, 59.49, 70.48, 73.04 and 62.21%, in maize, wheat, SM, GC and RB, respectively. Correspondingly, total SIAAD were 70.86, 61.30, 71.76, 75.13 and 64.05%. Least SIAAD values of amino acids were recorded in wheat compared to the other feedstuffs. Isoleucine had the highest increase in wheat and GC with 3.1 and 3.73%, respectively. In SM and maize, threonine had the lowest increase with 8.0 and 0.94%, respectively. Average increase of SIAAD over AIAAD for indispensable amino acid was 1.58, 1.95, 1.37, 2.24 and 2.10% for maize, wheat, SM, GC and RB respectively. Results from the present study showed that correcting AIAAD for endogenous losses using nitrogen-free method resulted in increased digestibility values for all the feedstuffs.

Effects of Dietary Xylanase and Arabinofuranosidase Combination on the Growth Performance, Lipid Peroxidation, Blood Constituents, and Immune Response of Broilers Fed Low-Energy Diets.

Simple SummaryArabinoxylans (AXs) constitute the major non-starch polysaccharides (NSPs) existent in maize and soybean meal, comprising about 52% and 65% of the total NSP. Previous works have illustrated that the incorporation of arabinofuranosidase (Abf; GH51) plus xylanase (Xyl; GH11) enhanced the dry matter digestibility of maize and wheat in vitro, in comparison with Xyl alone. In broilers, the combination of dietary Xyl and Abf (Rovabio® Advance) enhanced energy, fat, fiber, and protein utilizations. This study shows the effect of feeding low-energy diets with or without Rovabio® Advance, including high concentrations of Xyl and Abf, on the growth performance, nutrient digestibility, lipid peroxidation, blood constituents, and immune response of broilers. Our results confirm the improved growth, digestibility, and immunity obtained by enzymes supplementation. Furthermore, diets supplemented with enzymes caused a higher antibody titer against the Newcastle disease virus. Moreover, they enhanced plasma lipid profiles and antioxidation.The present study was conducted to examine that impact of dietary xylanase (Xyl) and arabinofuranosidase (Abf) supplementation on the performance, protein and fat digestibility, the lipid peroxidation, the plasma biochemical traits, and the immune response of broilers. A total of 480, un-sexed, and one-day-old broilers (Ross 308) were randomly divided into three treatments with eight replicates, where chicks in the first treatment were fed basal diets and served as the control, chicks in the second treatment were fed diets formulated with reductions of 90 kcal/kg, and chicks in the third treatment were fed the same formulated diets used in the second group as well as the Xyl and Abf combination (Rovabio® Advance). Feed intake was decreased by the low energy diet, leading to an enhancement in feed efficiency enzyme supplementation in the low energy diet (p < 0.015). Both protein and fat digestibility were improved (p < 0.047) due to enzyme supplementation. Moreover, enzyme supplementation increased muscle total lipids content and decreased muscle thiobarbituric acid retroactive substance content. Furthermore, diets supplemented with Xyl and Abf exhibited an increase in antibody titers against the Newcastle disease virus (p < 0.026). In addition, enzyme supplementation increased gene expression related to growth and gene expression related to fatty acid synthesis. It could be concluded that dietary Xyl and Abf supplementation had beneficial impacts on growth, nutrient digestibility, lipid peroxidation, immune response, and gene expressions related to growth and fatty acid synthesis in broiler chickens fed low-energy diets.

Characterisation and variability of greenhouse gas emissions from biomethane production via anaerobic digestion of maize

Biomethane is a renewable gas that can be used in existing infrastructure to reduce dependency on natural gas and lower greenhouse gas (GHG) emissions. Policy incentives have promoted a rapid implementation of biomethane production facilities using anaerobic digestion (AD). A range of feedstocks are used in AD including crops which have a higher GHG burden than most wastes and residues. The purpose of this research is to characterise and assess GHG emissions from typical operational biomethane facilities. It is imperative that GHG savings are obtained therefore quantifying emissions using a robust methodology is paramount. This study uses maize as a case study utilising data from several farms and AD facilities. Results show that calculated emissions for biomethane production from maize are 33.8 gCO2e/MJ of biomethane using the Renewable Energy Directive (RED) methodology. Key emission sources include N-fertiliser production, soil N2O emissions, imported electricity use, and fugitive methane. Sensitivity analysis performed assessed key data inputs and demonstrates how input inventory parameters affect the GHG balance and highlights variability in results. For the desired GHG savings to be achieved it is important that operators minimise fertiliser use, use nitrogen inhibitors, minimise imported electricity, and undertake close management of methane loss. This paper shows that although biomethane is considered a renewable, low carbon fuel, the inputs need to be carefully managed in order to achieve this.

Determination of true ileal phosphorus digestibility of maize and soybean meal and true ileal calcium digestibility of soybean meal for broiler chickens

Two experiments were conducted, using the regression method, to determine the true ileal phosphorus (P) digestibility of maize and soybean meal (SBM), and true ileal calcium (Ca) digestibility of SBM for broiler chickens. The aim of Experiment 1 was to determine true ileal P digestibility of maize and SBM. The experimental diets were formulated with four inclusion levels of each test ingredient to achieve graded concentrations of total P (2.5, 3.0, 3.5 and 4.0 g/kg, respectively). The P concentrations in maize-based diets were adjusted by the inclusion of monosodium phosphate. The Ca:total P ratio in all diets was maintained at 1.35 by the addition of limestone. Experiment 2 was conducted to determine true ileal Ca digestibility of SBM. Experimental diets were formulated to contain four levels of SBM to achieve graded concentrations of Ca (2.5, 3.0, 3.5 and 4.0 g/kg, respectively). Because of the low concentration of Ca in SBM, all diets were supplemented with a similar level of limestone to prevent any Ca deficiency. The Ca:total P ratio in all diets was adjusted to be equal by the addition of monosodium phosphate. In both experiments, titanium dioxide (3 g/kg) was used as the indigestible marker. One-day-old male broiler chicks were fed a commercial starter diet from 1 to 21 days of age. On Day 22, a total of 240 and 120 birds were assigned to eight and four dietary treatments in Experiments 1 and 2, respectively, with five replicate cages and six birds per cage. Birds were fed the experimental diets for 7 days. On Day 29, ileal digesta were collected from the posterior half of ileum, and the true P and Ca digestibility of test ingredients were calculated by linear regression analysis. True P digestibility of maize and SBM were determined to be 33.8% and 42.3%, respectively. True Ca digestibility of SBM was determined to be 45.9%.

Quantitative trait loci mapping of forage stover quality traits in six mapping populations derived from European elite maize germplasm

AbstractFour forage maize stover quality traits were analysed including in vitro digestibility of organic matter (IVDOM), neutral detergent fibre (NDF), water‐soluble carbohydrates (WSC) and digestibility of NDF (DNDF). We mapped quantitative trait loci (QTL) in three DH (doubled haploid) populations (totally 250–720 DH lines): one RIL population (358 lines) and two testcross (TC) populations, based on field phenotyping at multiple locations and years for each. High phenotypic and genotypic correlations were found for all traits and significant (p &lt; .01) at two locations, and NDF was negatively correlated with the other traits. QTL analyses were conducted by composite interval mapping. A total of 33, 23, 32 and 25 QTL were identified for IVDOM, NDF, WSC and DNDF, respectively, with three, four, five and two major QTL for each. Few consistent QTL for IVDOM, WSC and DNDF were detected in more than two populations. This study contributed to the identification of key QTL associated with forage maize digestibility traits and is beneficial for marker‐assisted breeding and fine mapping of candidate genes associated with forage maize quality.

Chemical composition and in vitro digestibility of whole-crop maize fertilized with synthetic fertilizer or digestate and harvested at two maturity stages in Boreal growing conditions

Maize cultivation for silage could be a sustainable option in Boreal conditions, especially when combined with nutrient recycling. Effects of digestate (sludge from biogas of domestic origin) application in comparison with synthetic fertilizer and two maturity stages on chemical composition and in vitro digestibility of whole-crop maize were investigated. Starch, neutral detergent fiber, water soluble carbohydrate (WSC) and digestible organic matter (DOM) contents of maize did not differ in response to the two fertilizer treatments. However, starch, DOM and metabolizable energy of maize increased, while ash, crude protein and WSC contents decreased with increasing maize maturity. Heavy metals in maize fertilized with digestate remained low. The results indicate that whole-crop maize fertilized with digestate and harvested at 150 days after sowing is a promising feed and has good nutritive value, even in Boreal conditions.

Effect of interactions between starch and chitosan on waxy maize starch physicochemical and digestion properties

ABSTRACTPhysicochemical and digestion properties of chitosan modified starch prepared by dry heat treatment were investigated. Starch granule aggregation occurred following the addition of chitosan and this trend was enhanced with increasing chitosan concentration. The size of chitosan modified starch particles was about six times of that of the native starch granules. Interactions between the hydroxyl groups of starch and the amino groups of chitosan was confirmed by Fourier transform infrared spectroscopy analysis. The disappearance of the trough in the Rapid Visco Analyzer profile indicated that the cross-links increased the starch shear resistance. The cross-links between starch and chitosan also reduced starch digestion rate compared to the control (p < 0.001), and this reduction was further enhanced with an increasing chitosan concentration. Additionally, the addition of chitosan altered starch digestion kinetics from one phase to two phases, implying that chitosan modification changed both starch structure and its digestion behaviors.

Genome-wide association analysis of forage quality in maize mature stalk.

BackgroundPlant digestibility of silage maize (Zea mays L.) has a large influence on nutrition intake for animal feeding. Improving forage quality will enhance the utilization efficiency and feeding value of forage maize. Dissecting the genetic basis of forage quality will improve our understanding of the complex nature of cell wall biosynthesis and degradation, which is also helpful for breeding good quality silage maize.ResultsAcid detergent fiber (ADF), neutral detergent fiber (NDF) and in vitro dry matter digestibility (IVDMD) of stalk were evaluated in a diverse maize population, which is comprised of 368 inbred lines and planted across seven environments. Using a mixed model accounting for population structure and polygenic background effects, a genome-wide association study was conducted to identify single nucleotide polymorphisms (SNPs) significantly associated with forage quality. Scanning 559,285 SNPs across the whole genome, 73, 41 and 82 SNPs were found to be associated with ADF, NDF, and IVDMD, respectively. Each significant SNP explained 4.2 %–6.2 % of the phenotypic variation. Underlying these associated loci, 56 genes were proposed as candidate genes for forage quality.ConclusionsOf all the candidate genes proposed by GWAS, we only found a C3H gene (ZmC3H2) that is directly involved in cell wall component biosynthesis. The candidate genes found in this study are mainly involved in signal transduction, stress resistance, and transcriptional regulation of cell wall biosynthetic gene expression. Adding high digestibility maize into the association panel would be helpful for increasing genetic variability and identifying more genes associated with forage quality traits. Cloning and functional validation of these genes would be helpful for understanding the molecular mechanism of the fiber content and digestibility. These findings provide us new insights into cell wall formation and deposition.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0919-9) contains supplementary material, which is available to authorized users.