Whole-plant Maize Research Articles

Influence of Ensiling Timing and Inoculation on Whole Plant Maize Silage Fermentation and Aerobic Stability (Preliminary Research)

Despite efforts to prevent atypical ensiling conditions, such as delayed ensiling or sealing, these issues frequently occur in practice. This study aimed to investigate the effects of delayed ensiling (forage held for 24 h) and sealing, along with inoculation using a blend of Lentilactobacillus buchneri and Lactococcus lactis, on the characteristics of the resulting silages. Whole-plant maize (Zea mays L.) was treated with or without a commercial inoculant and ensiled (36% dry matter) for 60 days in 3.0 L glass containers. The forage was either ensiled immediately or subjected to a 24 h delay before ensiling. During the delay, the forage was either covered or left uncovered. Each treatment was replicated five times. All data were analyzed using the MIXED procedure of SAS statistical software (version 9.4; SAS Institute Inc., Cary, NC, USA). Delaying the ensiling process by 24 h worsens fermentation parameters, significantly increases dry matter (DM) losses (p < 0.01), and significantly reduces aerobic stability and the hygienic quality of the silage (p < 0.01), as evidenced by higher concentrations of undesirable fermentation products and elevated yeast and mold counts. The inoculation has a significant impact on both forage before ensiling and the characteristics of the resulting silage. Maize forage treated with inoculant showed a lower temperature increase by 8.2–8.1 °C (p < 0.01) when delayed for 24 h before ensiling. In silages, it also resulted in a reduced pH (p < 0.01); increased concentrations of lactic acid; acetic acid; and 1,2-propanediol (p < 0.01); and decreased levels of negative fermentation indicators such as ammonia-N, alcohols, and butyric acid (p < 0.01) During both the fermentation and aerobic exposure periods, inoculated silages exhibited up to 36% and 2.6 times lower (p < 0.01) dry matter loss, while suppressing the growth of yeasts and molds by up to 2.6 and 3.1 times (p < 0.01), respectively, compared to non-inoculated silages. The results of this study support the recommendation to minimize the duration of aerobic exposure of fresh forage during silo filling and to use LAB-based inoculants.

Greenhouse gas and volatile organic compound emissions of additive-treated whole-plant maize silage: part A—anaerobic fermentation period

BackgroundSilage emits climate- and environment-relevant gases during fermentation and feed-out periods. This trial aimed to determine the unknown carbon dioxide (CO2), methane, nitrous oxide, ethanol, and ethyl acetate emissions of constant maize silage material over both periods. The results will be published in two consecutive articles (Part A: anaerobic fermentation period, Part B: aerobic storage period).MethodsThe untreated control (CON) was compared with the chemical additive treatment (CHE; 0.5 g sodium benzoate and 0.3 g potassium sorbate per kg fresh matter) and the biological additive treatment (BIO; 108 colony-forming units (CFU) Lentilactobacillus buchneri and 107 CFU Lactiplantibacillus plantarum per kg fresh matter). Barrel silos (n = 4) were connected to gas bags to quantify gas formation during anaerobic fermentation (30 or 135 ensiling days). Glass jar silos (n = 12) were used for laboratory silage analysis.ResultsCHE produced significantly (p < 0.05) less gas (6.7 ± 0.3 L per kg dry matter ensiled material (kgDM) until ensiling day 14.0 ± 0.0) and ethanol (8.6 ± 1.5 mg kgDM–1) than CON did (8.5 ± 0.2 L kgDM–1 until ensiling day 19.5 ± 6.4; 12.2 ± 1.5 (mg ethanol) kgDM–1). BIO indicates prolonged gas formation (9.1 ± 0.9 L kgDM–1 until ensiling day 61.3 ± 51.9; 12.0 ± 2.1 mg kgDM–1). CO2 is the main component of the gas formed. All treatments formed methane and nitrous oxide in small quantities. CON emitted significantly more CO2eq emissions than BIO and less than CHE (p < 0.05). Additives had no effect on ethyl acetate gas emissions. For BIO, ethanol concentrations in the material (rS = 0.609, p < 0.05) and gas quantities (rS = 0.691, p < 0.05) correlate with ethyl acetate gas quantities. All the treatments exhibited decreasing gas and CO2 quantities, and the dry matter mass increased between ensiling days 14 and 30 (− 0.810 ≤ rS ≤ 0.442; p < 0.05 to p = 0.20).ConclusionSilage generates climate- and environmental-relevant gases during fermentation and silage additives affect this pattern. Gas formation exceeds the fixation potential, and the carbon footprint of silage fermentation is negative.Graphical

Influence of Genotype and Anaerobic Fermentation on In Vitro Rumen Fermentation Characteristics and Greenhouse Gas Production of Whole-Plant Maize

The objective of this study was to evaluate the effect of anaerobic fermentation on the in vitro ruminal production of total gas (TG), methane (CH4), carbon monoxide (CO) and hydrogen sulfide (H2S), as well as on the characteristics of ruminal fermentation and CH4 conversion efficiency of whole-plant maize (WPM) from four native maize genotypes (Amarillo, Olotillo, Tampiqueño and Tuxpeño) from Mexico, and a commercial hybrid was used as a control. In all genotypes, the fermented WPM produced the lowest amounts (p ≤ 0.0236) of TG and CH4 from degraded dry matter (DM), and Tampiqueño and Tuxpeño presented the highest production of these gases. In addition, Tuxpeño also presented the highest proportion of CH4 (mL 100 mL−1 TG), and Olotillo presented the lowest proportion of both gases. Something similar occurred in H2S, where the fermented WPM produced the lowest (p ≤ 0.0077) amount per DM degraded, and Amarillo and Tampiqueño presented the highest and lowest production, respectively. However, the fermented WPM presented the highest (p = 0.0128) CO production from degraded DM, and Tuxpeño and Olotillo presented the highest and lowest production, while the rumen pH was lower (p &lt; 0.0001) in the fermented WPM, and Tuxpeño and Olotillo presented the highest and lowest pH, respectively. Furthermore, the fermented plant presented the greatest (p ≤ 0.0055) DM degradation, and the Amarillo and hybrid genotypes presented the highest percentages, while Olotillo presented the lowest. The short-chain fatty acid (SCFA) content and metabolizable energy (ME) did not differ (p ≥ 0.0899) between genotypes and were higher (p = 0.0009) in the fresh WPM. Despite the above, the fermented WPM was more efficient (p ≤ 0.0249), and the Amarillo and hybrid genotypes produced less CH4 per unit of SCFAs, ME and organic matter. In conclusion, the Amarillo genotype equaled the hybrid one, and although the production of CO increased, anaerobic fermentation showed the potential to reduce the rumen production of TG, CH4 and H2S, as well as to improve DM degradability and CH4 conversion efficiency.

Assessing the Effects of Dietary Cadmium Exposure on the Gastrointestinal Tract of Beef Cattle via Microbiota and Transcriptome Profile.

Cadmium (Cd) is an environmental pollutant, widely existing in soil, and can be absorbed and accumulated by plants. Hunan Province exhibits the worst cadmium contamination of farmland in China. Ruminants possess an abundant microbial population in the rumen, which enables them to tolerate various poisonous plants. To investigate whether the rumen microbiota could respond to Cd and mitigate the toxicity of Cd-accumulated maize to ruminants, 6-month-old cattle were fed with 85.82% (fresh basis) normal whole-plant maize silage diet (CON, n = 10) or Cd-accumulated whole-plant maize silage diet (CAM, n = 10) for 107 days. When compared to the CON cattle, CAM cattle showed significantly higher gain-to-feed ratio and an increased total bacterial population in the rumen, but a decreased total bacterial population in the colon. CAM cattle had higher relative abundance of Prevotella and Lachnospiraceae ND3007 group in the rumen, and Lachnospiraceae NK4A136 group and Clostridia vadinBB60 group in the colon. Notably, microbial correlations were enhanced in all segments of CAM cattle, especially Peptostreptococcaceae in the jejunum. Transcriptome analysis revealed down-regulation of several immune-related genes in the rumen of CAM cattle, and differentially expressed genes in the rumen were mostly involved in immune regulation. These findings indicated that feeding Cd-accumulated maize diet with a Cd concentration of 6.74 mg/kg dry matter (DM) could stimulate SCFA-related bacteria in the rumen, induce hormesis to promote weight gain, and improve energy utilization of cattle.

O92 (not presented) Effects of two kinds of lactic acid bacteria additives on fermentation quality of whole-plant maize silage

O92 (not presented) Effects of two kinds of lactic acid bacteria additives on fermentation quality of whole-plant maize silage

A Machine Learning-Based Assessment of Maize Silage Dry Matter Losses by Net-Bags Buried in Farm Bunker Silos

Estimating the dry matter losses (DML) of whole-plant maize (WPM) silage is a priority for sustainable dairy and beef farming. The study aimed to assess this loss of nutrients by using net-bags (n = 36) filled with freshly chopped WPM forage and buried in bunker silos of 12 Italian dairy farms for an ensiling period of 275 days on average. The proximate composition of harvested WPM was submitted to mixed and polynomial regression models and a machine learning classification tree to estimate its ability to predict the WPM silage losses. Dry matter (DM), silage density, and porosity were also assessed. The WPM harvested at over 345 (g kg−1) and a DM density of less than 180 (kg of DM m−3) was related to DML values of over 7%. According to the results of the classification tree algorithm, the WPM harvested (g kg−1 DM) at aNDF higher than 373 and water-soluble carbohydrates lower than 104 preserves for the DML of maize silage. It is likely that the combination of these chemical variables determines the optimal maturity stage of WPM at harvest, allowing a biomass density and a fermentative pattern that limits the DML, especially during the ensiling period.

Inoculation of whole-plant maize with viable lactic acid bacteria: effects on silage fermentation, aerobic stability and performance of dairy cows

Inoculation of whole-plant maize with viable lactic acid bacteria: effects on silage fermentation, aerobic stability and performance of dairy cows

A Meta-Analysis of the Effects of a Chemical Additive on the Fermentation and Aerobic Stability of Whole-Plant Maize Silage

Our objective was to conduct a meta-analysis on the effects of a chemical additive containing sodium benzoate, potassium sorbate, and sodium nitrite on the fermentation and aerobic stability of whole-plant maize silage. We used data from 28 experiments, with 56 untreated to treated comparisons, carried out over a 9-year period. The influence of dry matter (DM) content and length of ensiling on the additive effect were assessed by meta-regression and subgroup analysis. Treatment with the additive reduced the pH and concentrations of ammonia-N, lactic acid, and ethanol, but increased the concentration of residual reducing sugars, DM recovery, and aerobic stability (by about 5 days). As the forage DM decreased, there was a greater reduction in ethanol by the additive treatment. The additive reduced the number of yeasts in silages made with forage harvested at &gt;32% DM. The improvement in aerobic stability by the additive increased as ensiling time progressed. Overall, these findings show that the chemical additive has the ability to consistently and markedly improve the aerobic stability of maize silage under a wide range of conditions.

Nutritional quality of wet distillers’ grains co–ensiled with whole–plant maize and its feeding value for lambs

The high moisture content of wet distillers’ grains with solubles (WDGS) has limited its feeding value despite the relatively high nutritive value. The co–ensiling with whole–plant maize, as a complementary feed, was evaluated for growing lambs by formulating diets whose contents were: whole plant maize silage (WPMS) + sunflower oilcake meal (SOM) (control, WPMS + SOM), whole plant maize silage + dried distillers’ grains (WPMS + DDGS), and whole–plant maize (WPM) co–ensiled with WDGS (WPM – WDGS). Rumen fermentation parameters and in situ degradability of the diets were evaluated using three cannulated Merino wethers in a cross over 3 × 3 Latin square design experiment that lasted 39 days. Concurrently, feed intake and growth performance of South Africa Mutton Merino lambs (29.7 ± 3.6 kg) were evaluated over 45 days. The WPMS + DDGS diet had a lower rate of dry matter degradation (p < 0.05) compared to the WPMS + SOM and WPM–WDGS diets. However, the rapidly fermentable fraction, as well as the progressively fermentable fraction of the diet dry matter, was not different (p > 0.05). No differences in rumen volatile fatty acid, ammonia nitrogen concentration nor rumen pH of the wethers as a result of diet differences were observed. Lambs consuming the WDGS–based diet had a lower average daily intake and average daily gain (p < 0.05) compared to lambs consuming the DDGS and WPMS–based diets. However, the feed conversion ratio was not affected by diet differences (p > 0.05). In conclusion, co–ensiling WDGS with whole–plant maize provides the opportunity for the long–term storage and utilization of WDGS in lamb feeding.

Effect of Different Regions and Ensiling Periods on Fermentation Quality and the Bacterial Community of Whole-Plant Maize Silage.

This study aimed to explore the changes in the microbial community on the silage material surface and during the ensiling process of whole-plant maize in different regions. Whole-plant maize silages were sampled in Ziyun, Guanling, and Weinning counties within warm and humid climate areas in southern China. Silages were sampled at 0, 2, 5, 10, 20, and 45 days during ensiling. The nutritional components, fermentation properties, and microbiomes were examined to evaluate the influence of sampling area and fermentation time on the quality of silage. The results showed that the pH values of all silages significantly decreased (<4.2 at ensiling day 2) during fermentation and all silages achieved satisfactory fermentation at 45 days. Butyric acid was not detected during ensiling, and the contents of acetic acid and ammonia nitrogen in the final silages were below 6 g/kg DM and 50 g/kg total nitrogen, respectively. Weissella was the dominant epiphytic bacteria of raw material in Ziyun and Weinning, while Lactobacillus was prevalent in Guanling. Lactobacillus dominated the ensiling process, and its abundance significantly increased with increasing fermentation time in the three groups. Lactobacillus was negatively correlated with pH of all silages (p < 0.05) and positively correlated with lactic acid, propionic acid and acetic acid (p < 0.05). Furthermore, the bacterial community was significantly correlated with environmental factors. Altitude had a highly positive correlation with the abundance of Stenotrophomonas, Chryseobacterium, and Massilia (p < 0.01), while precipitation was negatively correlated with these bacteria. The humidity and average temperature significantly influenced the Lactobacillus and Weissella abundances of fresh whole-plant maize. During the ensiling process, the silages from three regions had similar bacterial dynamic changes, and the Lactobacillus formed and maintained good fermentation characteristics in whole-plant maize silage.

Influence of crude protein content and flint maize processing methods on the performance of early-weaning Nellore calves

AbstractThis study aims to determine the effects of dietary crude protein (CP) content of early-weaned calves; and the influence of flint maize processing methods on intake, total tract nutrient digestibilities and performance of Nellore heifer calves. Fifteen early-weaned Nellore female calves (4 ± 0.5 months; 108 ± 13.1 kg) were used. In phase 1, animals were fed one of the following diets for 112 days: 130, 145 or 160 g CP/kg dry matter (DM). In phase 2, animals received one of the two diets for 84 days: 0.60 dry ground maize grain, 0.30 whole-plant maize silage plus 0.10 mineral-protein supplement or 0.90 snaplage plus 0.10 mineral-protein supplement. In phase 1, intake and digestibility of dietary components were not affected (P &gt; 0.05) by increasing dietary CP content. Daily total urinary nitrogen (N) and urinary urea N increased (P &lt; 0.05) in response to increasing dietary CP content. Animal performance was not affected (P &gt; 0.05) by dietary CP content. In phase 2, maize processing methods did not affect (P &gt; 0.05) intake and digestibility of dietary components as well as animal performance, carcase characteristics and carcase composition. Therefore, based on the current experimental condition, we conclude that dietary CP concentrations of 130 g/kg DM can be indicated for early-weaned Nellore calves. However, more studies are recommended to validate this result and to evaluate concentrations below 130 g CP/kg DM for early-weaned Nellore calves. Moreover, snaplage could be used as an exclusive fibre and energy source for finishing cattle in feedlot.

Effect of Forage Processor Roll Gap Width and Storage Length on Fermentation Profile, Nutrient Composition, Kernel Processing Score, and Starch Disappearance of Whole-Plant Maize Silage Harvested at Three Different Maturities

Our objective was to assess the effect of forage processor roll gap width and storage length on fermentation, nutrient composition, kernel processing score (KPS), and ruminal in situ starch disappearance (isSD) of whole-plant maize silage harvested at different maturities. Samples from a single maize silage hybrid at three harvest maturities (1/4, 1/2, and 3/4 kernel milk line (early, intermediate, and late, respectively)) processed with two roll gap widths (1 and 3 mm) were collected and stored in quadruplicate vacuum pouches for 0, 30, 120, or 240 d. Lactic acid concentrations were greater, and pH was reduced in early and intermediate maturity silage compared to late maturity silage. Ruminal isSD was greatest for early maturity silage, intermediate for the intermediate maturity silage, and lowest for the late maturity silage, but differences in isSD due to maturity were diminished after prolonged storage. Kernel processing score was greatest in late maturity silage processed through a 1 mm roll gap and lowest in late maturity silage processed through the 3 mm roll gap. For early and intermediate maturity silages, no differences in KPS were observed between the two roll gap widths. Minimal effects of maturity and roll gap width on fatty acids (FA) and amino acids (AA) were observed. Concentrations of total AA decreased as storage length progressed. Results support the premise that the silo is a dynamic system that undergoes numerous chemical changes throughout the storage period.

In situ techniques to predict in vivo digestibility and to evaluate the impact of flint maize processing methods on degradation parameters

AbstractThis study aimed to (1) evaluate the effects of flint maize processing methods on the estimation of the readily soluble fraction (a), the potentially degradable fraction (b) and the rate of degradation of b (c) for dry matter (DM), organic matter (OM) and starch in the rumen; and (2) verify whether two different applications of in situ technique can be used to estimate in vivo DM, OM and starch digestibilities. Five ruminally cannulated Nellore bulls (265 ± 18.2 kg; 8 ± 1.0 mo) were distributed in a 5 × 5 Latin square. Three experimental diets were composed of 0.30 whole-plant maize silage, 0.10 supplement and 0.60 of one of the following processing methods: dry ground maize grain (DMG); high-moisture maize (HMM); reconstituted maize grain silage (RMG). Two additional diets were composed of 0.10 supplement, 0.80 snaplage and 0.10 stalklage (SNAP-80); or 0.10 supplement and 0.90 snaplage (SNAP-90). Digestibilities were estimated using in vivo procedure or predicted from in situ technique using a single 24 h incubation point or an equation proposed in previous literature. Diets based on ensiled grains presented greater (P &lt; 0.05) fraction a and c and lower (P &lt; 0.05) fraction b of DM, OM and starch compared to DMG. Both alternative use of in situ technique accurately estimated (P &gt; 0.05) in vivo DM, OM and starch digestibilities. The results suggest that ensilage process may increase the availability of nutrients. The two different applications of in situ technique showed precision and accuracy to estimate in vivo digestibility.

Influence of soybean-crop proportion on the conservation of maize-soybean bi-crop silage

Our objective was to determine the influence of soybean proportion on the conservation of maize-soybean bi-crop silages. We hypothesized that the aerobic stability of bi-crop silages would increase with the level of legume in the mixture, without affecting fermentative losses. Maize (Zea mays) and soybean (Glycine max) were cultivated in alternating rows within four 0.5-ha plots and manually harvested when the maize crop reached 330 g/kg of dry matter (DM). After cut, maize and soybean plants from each plot were chopped separately. Five proportions of whole-plant soybean were mixed with whole-plant maize, ensiled in laboratory silos (0, 125, 250, 375 and 500 g/kg of fresh matter) and stored for 90 d. As expected, crude protein increased linearly with the inclusion of soybean crop in the mixed silages (from 106 to 154 g/kg DM), mainly at the expense of soluble N. On the other hand, the addition of soybean increased DM loss during fermentation (from 59 to 109 g/kg) without altering yeast counts and aerobic stability of the silages. The increase in 2,3-butanediol, ethanol and acetic acid concentrations suggested that soybean addition favored the development of enterobacteria. In vitro DM and fiber digestibility linearly decreased with the inclusion of soybean, due to an increase in acid detergent fiber content. In conclusion, despite the expected increase in crude protein, mixing up to 500 g/kg of whole-plant soybean in whole-plant maize at ensiling did not improve aerobic stability, increased fermentative losses and reduced the in vitro digestibility of the silages compared with whole-plant maize silage.

Occurrence of aflatoxin B1, ochratoxin A and zearalenone in maize silage in the region of Vojvodina, Serbia

Abstract Silage made from the whole-plant maize is one of the most popular forages in Serbia. Consumption of maize silage by cows can be up to 30-35 kg/day. In Serbia in the few last years in the focus of the public and agriculture community were two mycotoxins, aflatoxin B1 and its metabolite aflatoxin M1 due to the outbreak of contaminated maize which affected the Balkans in 2012. Maize is regularly checked on the occurrence of aflatoxin B1, however forages are often neglected as a potential source of mycotoxins in the nutrition of dairy cattle. In this work, 48 samples of maize silage were analyzed for the occurrence of aflatoxin B1, ochratoxin A and zearalenone. Samples were collected from three regions (Bačka, Banat and Srem) in Vojvodina. In all samples, at least one mycotoxin above the limit of quantification was measured. Aflatoxin B1 was detected in 36 (75%) samples. In two samples from Banat, the concentration of aflatoxin B1 exceeded the maximum level (ML) set by Serbian regulation (30 µg/kg at moisture content of 12%). In seven samples, the concentration of aflatoxin B1 was above 20 µg/kg which is the EU regulated ML. Average concentration of ochratoxin A was 10.4 µg/kg, while the maximum measured value was 34.3 µg/kg. Maximum zearalenone content in all samples was 538 µg/kg while the average zearalenone concentration was 138 µg/kg. The results from this research point out that mycotoxin contaminated silage in the region of Vojvodina, Serbia can significantly contribute to daily intake of aflatoxin B1 in dairy cattle.

Digestibility contributes to between-animal variation in feed efficiency in beef cows

Residual feed intake (RFI) is an alternative measure of feed efficiency (FE) and is calculated as the difference between actual and expected feed intake. The biological mechanisms underlying animal-to-animal variation in FE are not well understood. The aim of this study was to investigate the digestive ability of beef cows selected for RFI divergence as heifers, using two contrasted diets. Fifteen 4-year-old beef cows were selected from a total of 69 heifers based on their RFI following the feedlot test. The selected heifers were ranked into high-RFI (+ 1.02 ± 0.28, n = 8) and low-RFI (−0.73 ± 0.28, n = 7), and a digestibility trial was performed after their first lactation. Both RFI groups were offered two different diets: 100% hay or a fattening diet which consisted of a DM basis of 67% whole-plant maize silage and 33% high starch concentrates over four experimental periods (two per diet). A diet effect was observed on feed intake and apparent digestibility, whereas no diet × RFI interaction was detected (P > 0.05). Intake and apparent digestibility were higher in cows fed the fattening diet than in those fed the hay diet (P < 0.0001). DM intake (DMI) and organic matter apparent digestibility (OMd) were repeatable and positively correlated between the two subsequent periods of measurements. For the hay and fattening diets, the repeatability between periods was r = 0.71 and r = 0.73 for DMI and r = 0.87 and r = 0.48 for OMd, respectively. Moreover, both intake (r = 0.55) and OMd (r = 0.54) were positively correlated (P < 0.05) between the hay and fattening diets. Significant differences between beef cows selected for divergence in RFI as heifers were observed for digestive traits (P < 0.05), DM and organic matter (OM) apparent digestibility being higher for low-RFI cows. Overall, this study showed that apparent digestibility contributes to between-animal variation in FE in beef cows.

Effects of defoliation on whole‐plant maize characteristics as forage and energy crop

AbstractHail affects yield and quality of maize crops, and consequences also depend on the growth stage at which the injury occurred. Whole‐plant maize (WPM) silage is often used within the same farm for cattle feeding and biogas production. The present study aimed to verify the effects of hail damage, simulated by artificial defoliation, on yield and chemical and nutritional features, as well as on biochemical methane potential (BMP) of maize forage. In a randomized block design with three replicates, four defoliation levels (0%, 33%, 66% and 100% of leaf area removal respectively) have been applied at either the V12 (12th leaf), R1 (silking) or R3 (milk) stages for two consecutive years. WPM yield, chemical and nutritional features, and BMP were measured. Dry‐matter (DM) yield per hectare was progressively reduced (p &lt; 0.001) with increasing levels of defoliation and with application at V12 in comparison with R1 or R3 (1.26 vs. 1.39 and 1.46 kg ha−1 for V12 vs. R1 and R3; p &lt; 0.003). Nutritive value and BMP per unit of product were less altered than dry‐matter yield per hectare by defoliation. Anticipating defoliation reduced net energy for lactation (5.26 vs. 5.46 MJ kg−1 DM for V12 and R3 respectively; p = 0.02). Total defoliation resulted in an accumulation of nitrates (NO3) compared to the other treatments (3.98 vs. 1.53 g NO3 kg−1 DM; p &lt; 0.001). BMP was mainly reduced by early and complete defoliation. Equations were developed to estimate the effects of defoliation on yield, composition, and nutritive and energetic values of WPM.

Diversity of bacterial community during ensiling and subsequent exposure to air in whole-plant maize silage.

ObjectiveTo describe in-depth sequencing, the bacterial community diversity and its succession during ensiling of whole-plant maize and subsequent exposure to air.MethodsThe microbial community dynamics of fermented whole-plant maize for 60 days (sampled on day 5, 10, 20, 40, 60) and subsequent aerobic exposure (sampled on day 63 after exposure to air for 3 days) were explored using Illumina Miseq sequence platform.ResultsA total of 227,220 effective reads were obtained. At the genus level, there were 12 genera with relative abundance >1%, Lactobacillus, Klebsiella, Sporolactobacillus, Norank-c-cyanobacteria, Pantoea, Pediococcus, Rahnella, Sphingomonas, Serratia, Chryseobacterium, Sphingobacterium, and Lactococcus. Lactobacillus consistently dominated the bacterial communities with relative abundance from 49.56% to 64.17% during the ensiling process. Klebsiella was also an important succession bacterium with a decrease tendency from 15.20% to 6.41% during the ensiling process. The genus Sporolactobacillus appeared in late-ensiling stages with 7.70% abundance on day 40 and 5.32% on day 60. After aerobic exposure, the Lactobacillus decreased its abundance from 63.2% on day 60 to 45.03% on d 63, and Klebsiella from 5.51% to 5.64%, while Sporolactobacillus greatly increased its abundance to 28.15%. These bacterial genera belong to 5 phyla: Firmicutes (relative abundance: 56.38% to 78.43%) was dominant, others were Proteobacteria, Bacteroidetes, Cyanobacteria, and Actinobacteria. The bacterial communities clearly clustered into early-ensiling (d 5), medium-ensiling (d 10, d 20), late-ensiling (d 40, d 60), and aerobic exposure (d 63) clusters, with early- and late-ensiling communities more like each other than to the aerobic exposure communities.ConclusionHigh-throughput sequencing based on 16S rRNA genes proved to be a useful method to explore bacterial communities of silage. The results indicated that the bacterial communities varied during fermentation and more dramatically during aerobic exposure. The study is valuable for understanding the mechanism of population change and the relationship between bacteria and ensilage characteristics.

Fatty acid composition of maize silages from different hybrids

Fatty acid composition of maize silages from different hybrids

The use of cobs, a by-product of maize grain, for energy production in anaerobic digestion

Owing to the rising energy demand and the conflict between food, feed and energy crops for agricultural land, there is a growing need for alternative biomasses for energy purposes. New developments in harvesting technology have created the possibility of harvesting cobs as a by-product of maize grain harvesting. The aim of the present work has been to evaluate the potential and limitations of maize cob utilisation in an anaerobic digestion chain, considering the main agronomic, productive and qualitative traits. Maize grain and cob yields as well as the moisture content of samples collected from 1044 (farm) fields (located) in North West Italy have been determined over the 2012 growing season. Moreover, 27 representative fields were harvested using a modified combine-harvester that is able to collect maize grains and threshed cobs separately. The chemical composition and biochemical methane potential (BMP) of the cobs have been analysed. The relative potential yield of maize cobs was established as 18.7% of the grain mass, while the wet cob yield recorded in the field after mechanical harvesting was 1.6 t ha–1. The total solid content was 60%. Fibre fractions represented over 85% of the dry cob matter, lignin content was about 16%, while the protein, ash, lipids and macro-elements (nitrogen, phosphorus, potassium) contents were very low compared to the whole-plant maize used for silage. The average BMP of wet threshed cob was 250±20 Nm3 t VS–1. Collected data have underlined that maize cobs could be used as a sustainable feedstock for anaerobic digestion processes.