Whole-crop Maize Research Articles

The contribution of epiphytic microbiota in oat and Italian ryegrass to silage fermentation products and bacterial community structure of whole-crop maize

BackgroundThe purpose of this research is to study the contribution of epiphytic microbiota in fresh oat (OT), Italian ryegrass (IR) and whole-crop maize (MZ) to silage fermentation products and bacterial community structure of MZ. After γ-ray irradiation, the sterile MZ was treated via microbiota transplantation method: (1) sterile deionized water (STMZ); (2) microbiota epiphytic on MZ (MZMZ); (3) microbiota epiphytic on OT (MZOT); (4) microbiota epiphytic on IR (MZIR). Triplicate silos of each treatment were tested after 1, 3, 7, 15, 30 and 60 days of ensiling.ResultsMZMZ had higher (P < 0.05) lactic acid contents, and lower (P < 0.05) ammonia nitrogen and ethanol contents than MZIR and MZOT on day 60. The relative abundance of Lactobacillus in MZMZ decreased from 84.0% on day 3 to 44.7% on day 60. MZMZ had higher (P < 0.05) abundances of ‘Nucleotide metabolism’, ‘Replication and repair’ and ‘Membrane transport’, and lower (P < 0.05) abundance of ‘Amino acid metabolism’ than MZOT and MZIR on day 3.ConclusionsThe silage fermentation products of MZ were highly affected by the activity and compositions of epiphytic microbiota. The Enterobacteriaceae, Hafnia-Obesumbacterium, hetero-fermentative and acid-resistant Lactobacillus took primary responsibility for the high dry matter loss and ethanol contents and low lactic acid contents in MZ silage.Graphical

The Effects of Short-Time Delayed Sealing on Fermentation, Aerobic Stability and Chemical Composition on Maize Silages

Despite the efforts to improve the methodological standards of silage trials, many factors that can influence the results of lab-scale studies need to be better understood. This study aimed to determine the effects of short-time delayed sealing and inoculation with a blend of Lentilactobacillus buchneri and Lactiplantibacillus plantarum on fermentation, aerobic stability, and chemical composition of silages. Whole-crop maize was treated with or without a commercial inoculant and ensiled (29.3% dry matter) for 55 days in 8.8 L PVC silos that were sealed immediately (up to 30 min delay) or after a delay (90, 150, or 210 min between chopping and sealing) with five replicates each. The increasing air exposure before sealing increased fermentation losses and reduced silage nutritional value. Crude protein and ash were significantly affected by inoculation, with control treatments showing higher ash and lower protein values. Lignin, neutral detergent fiber, and acid detergent fiber were only affected by the delay period. The longer the sealing delay, the higher the gas production, and the lower the starch values and lactic acid content observed in samples. Inoculation was inefficient in reducing total dry matter losses, but it increased aerobic stability, acetic acid, and ethanol contents of silages and reduced effluent loss. Control silages had higher total dry matter loss during the aerobic exposure than inoculated silages. The results confirmed that the delay periods tested were long enough to negatively interfere with the chemical composition of silages, especially the fibrous fraction content.

Effects of lactic acid bacteria inoculant level and ensiling time on nutritional value and fermentation quality of whole-crop maize silage

Effects of lactic acid bacteria inoculant level and ensiling time on nutritional value and fermentation quality of whole-crop maize silage

Effects of silage sealing films on fermentation dynamics of ensiled maize and nutrient utilization by Damara rams

An experiment was conducted to evaluate the effects of two silage sealing films on whole crop maize (WCM) fermentation, aerobic stability and nutrient digestion by rams. Prior to ensiling (day 0), triplicate samples of the WCM were collected to determine dry matter, pH, water-soluble carbohydrates (WSC), lactic acid (LA) bacterial counts and nutrient concentration. A single bunker silo was divided into eight sections that were ensiled using either a standard polyethylene film (PE) or an orange oxygen barrier (OB) Silostop film for 180 days. After 180 days of ensiling, six silage samples were collected from each replicate. Three samples were used for nutrient analysis and the other three to determine aerobic stability. Sixteen four-year-old Damara rams with an average live weight of ± 54 kg were housed individually in wooden pens (2.2 m2) to determine digestibility of nutrient in the silage. The digestibility study was conducted as a switchover design with four feeding phases. The silage was supplemented daily with 1% urea and fed to the rams ad libitum. Nutritional value of the silage was not (P &gt;0.05) affected by the ensiling films. The OB-ensiled maize had higher (P &lt;0.05) LA, lower pH, CO2 production and yeast and mould populations, and lower WSC compared with the PE-ensiled maize. Dry matter intake, nutrient digestion and nitrogen balance of rams fed the silage were not affected (P &gt;0.05) by treatments. The OB film improved the fermentation and aerobic stability of WCM silage but did not influence its nutrient utilization by rams.&#x0D; Keywords: cereals, digestibility, forage, rams, nitrogen, supplementation

The Effect of Time and Method of Storage on the Chemical Composition, Pepsin-Cellulase Digestibility, and Near-Infrared Spectra of Whole-Maize Forage

This study examined the effects of long-term storage conditions on the chemical composition, pepsin-cellulase dry matter digestibility (PCDMD), and visible (VIS)/near infrared spectra (NIR) of forage. Eighteen samples of different whole-crop maize varieties originally harvested in 1987 were used. After drying, these samples were analyzed in the laboratory for ash, crude protein (CP), structural carbohydrates, total soluble carbohydrates (TSC), starch and PCDMD, and the remaining samples were stored frozen (at −20°C) or at barn temperature (ambient temperatures ranged from −8.5 °C to 27.1 °C). In 2016, the samples were analyzed for ash, CP, structural carbohydrates, TSC, starch and PCDMD. The visible/NIR spectra of both storage methods were obtained. Chemical composition and PCDMD analyses revealed significant differences (p &lt; 0.05) between the storage methods for TSC but not for the other parameters (p &gt; 0.05). After sample harvesting in 1987, the analyses were compared with those in 2016. It was found that the post-harvest TSC and ash content were higher (p &lt; 0.05) and lower (p &lt; 0.05), respectively, during 2016. No significant differences were found for starch and PCDMD. Important differences between the VIS/NIR spectra of both storage methods were obtained in the VIS segment, particularly in the area between 630 and 760 nm. We concluded that storing dry forage samples at ambient temperature for a very long time (29 years) did not change their nutritive value compared to the values obtained before storage.

Effects of exogenous amylase on the in vitro digestion kinetics of whole-crop maize silages made from flint or dent grain type at different phenological stages grown in tropical condition.

The effect of exogenous amylase on the in vitro rumen digestion kinetics of whole-crop maize silage made from dent (RB9004) or flint grain type (RB9308) was evaluated at different phenological stages: soft dough (SOD), early dent (EAD), ½ milkline (½M) and ¾ milkline (¾M). Forage was harvested from 70 to 110days after sowing. Two rumen-cannulated cows receiving or not exogenous amylase (0.7g/kg dry matter-DM, provided to achieve 396 kilo Novo units of amylase activity/kg of TMR DM) were used as donor of ruminal fluid. The in vitro gas production kinetics was evaluated according to a dual-pool logistic model. The chemical composition and gas production kinetics were affected by the hybrid and phenological stages. The flint hybrid had lower range for chemical analysis among physiological stages. Harvesting at ½M and ¾M improved DM content, bromatological composition and silage quality parameters compared to dent or flint types. Amylase (i) increased methane (CH4 ) production and in vitro dry matter digestibility (IVDMD) in ½M stage, (ii) improved digestion kinetics by reducing lag time and increasing total gas production and fermentation rates of non-fibrous carbohydrates (NFC) and fibrous carbohydrates (FC), and (iii) increased extent and fermentation rate of NFC and increased fermentation rate of FC fraction in whole-crop maize silages produced from dent or flint types in all phenological stages. Harvesting between ½M and ¾M is the best phenological stage to improve chemical composition and silage quality parameters. Exogenous amylase showed improvements on fibre digestion of silages at ½M and ¾M phenological stages in both grain types of corn.

Effects of ethyl ester supplementation to forage on short-term dry matter intake and preference by goats

ABSTRACTIn whole-crop maize silages with atypical smell and decreased acceptance by ruminants, high concentrations of the volatile organic compounds ethyl acetate (EA) and ethyl lactate (EL) were detected. The aim of this study was to evaluate the impact of different concentrations of ethyl esters added to forage on preference and short-term feed intake of goats. In the first of three trials, whole-crop maize silage was supplemented with different concentrations of EA and EL and then vacuum-stored before use. Forages sampled during the preference trial showed a good recovery of EL with a high accordance of target (naturally formed + supplemented) and analysed concentrations. Supplemented EA was not recovered, making transient storage of substrates before use in feeding trials equivocal. However, four treatments with different concentrations of EL (approximately 330, 560, 920 and 1300 mg/kg dry matter (DM)) were used for the preference trial. In Trials 2 and 3, EA and EL (with and without ethanol, respectively) were added to grass hay directly before offering the feed, each in concentrations of 0, 600 and 1200 mg/kg DM to have six treatments each. In all trials, each possible combination of treatments was offered to Saanen-type wethers (n = 10, Trial 1; n = 5, Trials 2 and 3) as free choice in preference trials. In Trial 1, there was only a weak impact of EL on preference behaviour as goats avoided medium EL concentrations, but did not avoid silages with higher concentrations. In Trials 2 and 3, there was no influence of added volatiles on short-term DM intake and preference at all. It can be concluded that it is unlikely that ethyl esters as single substance or in combination with ethanol affect preference behaviour and feed intake of ruminants. Possibly a combination or still unidentified fermentation products cause avoidance instead of a single compound.

Detecting dry matter yield trend of whole crop maize considering the climatic factors in the Republic of Korea

AbstractThis study was aimed to detect the dry matter yield (DMY) trend of whole crop maize (WCM) considering the climatic factors responsible for growth and development of WCM using time series analysis in the Republic of Korea. The dataset consisted of DMY and climatic factors responsible for WCM yield from 1982 to 2011. The stationarity of the DMY was detected using augmented Dickey–Fuller (ADF) test, whereas the parameters of Autoregressive (AR) and Moving average (MA) were estimated from correlogram of Autocorrelation function (ACF) and partial ACF (PACF). The stationary DMY data was fitted to AR Integrated MA (ARIMA), and based on model selection criterion, ARIMA (2, 0, 1) was detected as the optimal model to describe the DMY trend of WCM. The DMY trend followed the mean of the preceding 2 years and residual of preceding 1 year. ARIMA with exogenous variables (ARIMAX) detected Seeding‐Harvesting Growing Degree Days (SHGDD, °C), Seeding‐Harvesting Rainfall Amount (SHRFA, mm), and Seeding‐Harvesting Rainfall Days (SHRFD, days) as major climatic factors responsible for the DMY trend of WCM. Furthermore, the amount and timing of rainfall found to be an important factor for the observed DMY trend. The fluctuation in the DMY trend implies the need to come up with a holistic approach that include new varieties development and improved agronomic management system to overcome the expected challenge from climate variability.

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.

Wydajnosc, sklad i jakosc mleka kr�w zywionych kiszonka z kukurydzy okryta folia oksybiodegradowalna

The aim of the study was to determine if oxobiodegradable film can be used as an alternative to standard film for silage making in agricultural practice. Whole-crop maize silage covered with oxobiodegradable film was fed as a component of partly mixed ration (PMR) for dairy cows. The oxobiodegradable coating used to cover the silage heap ensured that the fermentation process was normal, as evidenced by the quality parameters (pH 3.8, 72 hours of aerobic stability) and chemical composition of the silages. Fodder covered with biodegradable material contained less ammonium nitrogen than silage with standard foil (55.3 vs. 66.63 g·kg-1 N total, respectively). The concentration of lactic acid was also lower (77.75 vs. 89.65 g·kg-1 dry matter). Feeding whole-crop maize silage covered with oxobiodegradable film had no adverse effect on productivity (daily 30.65 vs. 31.17 kg fat corrected milk – FCM respectively), composition (protein – 3.33 in the experimental group vs. 3.3% in the control group, fat – 3.89 vs. 3.79%) and some technological suitability of milk.

Faecal characteristics and milk production of dairy cows in early-lactation fed diets differing in forage types in commercial herds

ABSTRACTEffects of grass–clover silage (GCS) alone or combined with whole-crop cereal silage, maize silage (MS) or ensiled pressed sugar beet pulp (EPSB) on faecal characteristics and performance of early-lactation dairy cows were studied in 26 herds. Data were analysed with herd as the experimental unit and correlation coefficients among the variables were estimated. Feeding MS combined with GCS resulted in faeces of a firmer consistency (P < .05), containing more undigested fibre compared to feeding GCS alone or with EPSB (P < .05). There was a strong positive correlation between the number of grains and starch concentration in faeces (r = 0.83, P < .001). Increasing forage dry matter (DM) intake decreased faecal DM concentration (r = −0.54, P < .01) but seems to result in cleaner cows, whereas increasing DM intake of concentrate increased faecal DM concentration (r = 0.63, P < .01) but might result in dirtier cows.

사일리지용 옥수수의 건물수량에 영향을 미치는 기후요인 탐색

The purpose of this research is to identify the significance of climate factors related to the significance of change of dry matter yield (DMY) of whole crop maize (WCM) by year through the exploratory data analysis. The data (124 varieties; n=993 in 7 provinces) was prepared after deletion and modification of the insufficient and repetitive data from the results (124 varieties; n=1027 in 7 provinces) of import adaptation experiment done by National Agricultural Cooperation Federation. WCM was classified into early-maturity (25 varieties, n=200), mid-maturity (40 varieties, n=409), late-maturity (27 varieties, n=234) and others (32 varieties, n=150) based on relative maturity and days to silking. For determining climate factors, 6 weather variables were generated using weather data. For detecting DMY and climate factors, SPSS21.0 was used for operating descriptive statistics and Shapiro-Wilk test. Mean DMY by year was classified into upper and lower groups, and a statistically significant difference in DMY was found between two groups (p 0.05). These results indicate that the SHAGDD, SHP and SHH are related to DMY of WCM, but the comparison of R 2 among three variables (SHAGDD, SHP and SHH) couldn’t be obtained which is needed to be done by regression analysis as well as the prediction model of DMY in the future study.

Review on Mycotoxin Issues in Ruminants: Occurrence in Forages, Effects of Mycotoxin Ingestion on Health Status and Animal Performance and Practical Strategies to Counteract Their Negative Effects.

Ruminant diets include cereals, protein feeds, their by-products as well as hay and grass, grass/legume, whole-crop maize, small grain or sorghum silages. Furthermore, ruminants are annually or seasonally fed with grazed forage in many parts of the World. All these forages could be contaminated by several exometabolites of mycotoxigenic fungi that increase and diversify the risk of mycotoxin exposure in ruminants compared to swine and poultry that have less varied diets. Evidence suggests the greatest exposure for ruminants to some regulated mycotoxins (aflatoxins, trichothecenes, ochratoxin A, fumonisins and zearalenone) and to many other secondary metabolites produced by different species of Alternaria spp. (e.g., AAL toxins, alternariols, tenuazonic acid or 4Z-infectopyrone), Aspergillus flavus (e.g., kojic acid, cyclopiazonic acid or β-nitropropionic acid), Aspergillus fuminatus (e.g., gliotoxin, agroclavine, festuclavines or fumagillin), Penicillium roqueforti and P. paneum (e.g., mycophenolic acid, roquefortines, PR toxin or marcfortines) or Monascus ruber (citrinin and monacolins) could be mainly related to forage contamination. This review includes the knowledge of mycotoxin occurrence reported in the last 15 years, with special emphasis on mycotoxins detected in forages, and animal toxicological issues due to their ingestion. Strategies for preventing the problem of mycotoxin feed contamination under farm conditions are discussed.

Effect of temperature and duration of ensiling on in vitro degradation of maize silages in rumen fluid.

The effects of ensiling temperature and duration of ensiling on the feeding quality of whole-crop maize (Zea mays L.) silages were investigated. Samples of one cultivar of maize plants were collected from two different fields, grown in different years on sandy soils. Samples were collected when the whole-plant dry matter content was approximately 330g/kg. Maize plants were chopped and ensiled in mini silos at three different ambient temperatures (5, 12 and 18°C). The ensiling temperature affected the ensiling fermentation processes, causing different rates of pH decline and different final pH values. Samples from the silos were taken after 0 (not ensiled, i.e. control), 4, 8 and 16weeks of ensiling. The silage samples were not dried, but ground-frozen under liquid nitrogen to pass a 1-mm sieve. The gas production technique was used to evaluate the influence of the ensiling temperature and the duration of ensiling on the degradation of the silage samples in rumen fluid. The gas production was highest when the maize was ensiled at 12°C (p<0.0001). An increase in ensiling duration caused a decrease in silage pH, accompanied by a decrease in gas production (p<0.0001). The decrease in gas production was linearly related to the decrease in pH at the three temperatures. The present study shows that both ensiling temperature and ensiling duration play a significant role in the rumen degradability of maize silage.

Effects of maize maturity at harvest and dietary proportion of maize silage on intake and performance of growing/finishing bulls

Whole-crop maize silage as forage in diets of finishing cattle can promote high intakes and thus, enhances animal performance. In the present study we evaluated the effect of whole-crop maize maturity at harvest and the proportion of maize-silage in diets of finishing bulls, on feed intake and performance. An indoor experiment with 64 dairy bulls was replicated over two consecutive rearing periods, under the same experimental design. Two groups of 4 light and two groups of 4 heavy bulls were randomly allocated into one of the 4 dietary treatments, which formed a 2×2 factorial arrangement of treatments, involving two maturity stages of maize at harvest (i.e. dough stage or dent stage) and two maize silage proportions (i.e. 100% maize silage or 50% maize and 50% grass silage). The diets were offered ad libitum as total mixed rations (TMRs) with inclusion of concentrates (i.e. rolled barley; dried distillers’ grain plus soluble; cold-pressed rapeseed cake) in a 40% proportion on DM basis. All animals were slaughtered at a target body weight of 630kg. Bulls fed on diets containing maize silage as sole forage achieved higher live-weight gain (P<0.01) compared to their counterparts. This is likely due to the higher ME (P<0.01) and CP (P<0.001) intakes they achieved. Interestingly, the dough stage compared to dent stage maturity of maize at harvest tended to increase live-weight gain (P=0.06).

Occurrence of pre- and post-harvest mycotoxins and other secondary metabolites in Danish maize silage.

Maize silage is a widely used feed product for cattle worldwide, which may be contaminated with mycotoxins, pre- and post-harvest. This concerns both farmers and consumers. To assess the exposure of Danish cattle to mycotoxins from maize silage, 99 samples of whole-crop maize (ensiled and un-ensiled) were analyzed for their contents of 27 mycotoxins and other secondary fungal metabolites by liquid chromatography-tandem mass spectrometry. The method specifically targets the majority of common pre- and post-harvest fungi associated with maize silage in Denmark. Sixty-one samples contained one or more of the 27 analytes in detectable concentrations. The most common mycotoxins were zearalenone, enniatin B nivalenol and andrastin A, found in 34%, 28%, 16% and 15% of the samples, respectively. None of the samples contained mycotoxins above the EU recommended maximum concentrations for Fusarium toxins in cereal-based roughage. Thus, the present study does not indicate that Danish maize silage in general is a cause of acute single mycotoxin intoxications in cattle. However, 31 of the samples contained multiple analytes; two samples as much as seven different fungal metabolites. Feed rations with maize silage may therefore contain complex mixtures of fungal secondary metabolites with unknown biological activity. This emphasizes the need for a thorough examination of the effects of chronic exposure and possible synergistic effects.

Effects of Ensiling Fermentation and Aerobic Deterioration on the Bacterial Community in Italian Ryegrass, Guinea Grass, and Whole-crop Maize Silages Stored at High Moisture Content.

The effects of storage period and aerobic deterioration on the bacterial community were examined in Italian ryegrass (IR), guinea grass (GG), and whole-crop maize (WM) silages. Direct-cut forages were stored in a laboratory silo for 3, 7, 14, 28, 56, and 120 d without any additives; live counts, content of fermentation products, and characteristics of the bacterial community were determined. 2,3-Butanediol, acetic acid, and lactic acid were the dominant fermentation products in the IR, GG, and WM silages, respectively. The acetic acid content increased as a result of prolonged ensiling, regardless of the type of silage crop, and the changes were distinctively visible from the beginning of GG ensiling. Pantoea agglomerans, Rahnella aquatilis, and Enterobacter sp. were the major bacteria in the IR silage, indicating that alcoholic fermentation may be due to the activity of enterobacteria. Staphylococcus sciuri and Bacillus pumilus were detected when IR silage was spoiled, whereas between aerobically stable and unstable silages, no differences were seen in the bacterial community at silo opening. Lactococcus lactis was a representative bacterium, although acetic acid was the major fermentation product in the GG silage. Lactobacillus plantarum, Lactobacillus brevis, and Morganella morganii were suggested to be associated with the increase in acetic acid due to prolonged storage. Enterobacter cloacae appeared when the GG silage was spoiled. In the WM silage, no distinctive changes due to prolonged ensiling were seen in the bacterial community. Throughout the ensiling, Weissella paramesenteroides, Weissella confusa, and Klebsiella pneumoniae were present in addition to L. plantarum, L. brevis, and L. lactis. Upon deterioration, Acetobacter pasteurianus, Klebsiella variicola, Enterobacter hormaechei, and Bacillus gibsonii were detected. These results demonstrate the diverse bacterial community that evolves during ensiling and aerobic spoilage of IR, GG, and WM silages.

Prediction models of silage fermentation products on crop composition under strict anaerobic conditions: A meta-analysis

A meta-analysis was conducted to establish linkages between crop and fermentation variables. Data from well-controlled mini silage studies were used in which no additives had been used and no ingress of air had occurred. The silage set consisted of data on crop chemical composition and epiphytic lactic acid bacteria count, and fermentation products (organic acids, alcohols, and ammonia-N) from 118 silages made from 30 grass, 7 legume, 15 grass and legume mixtures, and 66 whole-crop maize samples. The prediction models for fermentation products on crop variables were obtained by stepwise multiple regression analysis. Perennial forage and maize silages were analyzed separately. The best models were obtained for acetic acid in perennial forage silages, with a coefficient of determination of 0.63, and for lactic acid and ethanol in whole-crop maize silages, with coefficients of determination of 0.84 and 0.61, respectively. Fermentation products of perennial forage and maize silages were best related to dry matter and crude protein contents, respectively. Overall, the prediction equations were weak.

Aerobic deterioration stimulates outgrowth of spore-forming Paenibacillus in corn silage stored under oxygen-barrier or polyethylene films

The occurrence of Bacillus and Paenibacillus spores in silage is of great concern to dairy producers because their spores can survive pasteurization and some strains are capable of subsequently germinating and growing under refrigerated conditions in pasteurized milk. The objectives of this study were to verify the role of aerobic deterioration of corn silage on the proliferation of Paenibacillus spores and to evaluate the efficacy of oxygen-barrier films used to cover silage during fermentation and storage to mitigate these undesirable bacterial outbreaks. The trial was carried out on whole-crop maize (Zea mays L.) inoculated with a mixture of Lactobacillus buchneri, Lactobacillus plantarum, and Enterococcus faecium. A standard polyethylene film and a polyethylene-polyamide film with an enhanced oxygen barrier were used to produce the silage bags for this experiment. The silos were stored indoors at ambient temperature (18 to 22°C) and opened after 110 d. The silage was sampled after 0, 2, 5, 7, 9, and 14 d of aerobic exposure to quantify the growth of endospore-forming bacteria during the exposure of silages to air. Paenibacillus macerans (gram-positive, facultatively anaerobic bacteria) was able to develop during the aerobic exposure of corn silage. This species was present in the herbage at harvesting, together with clostridial spores, and survived ensiling fermentation; it constituted more than 60% of the anaerobic spore formers at silage opening. During silage spoilage, the spore concentration of P. macerans increased to values greater than 7.0 log10 cfu/g of silage. The use of different plastic films to seal silages affected the growth of P. macerans and the number of spores during aerobic exposure of silages. These results indicate that the number of Paenibacillus spores could greatly increase in silage after exposure to air, and that oxygen-barrier films could help to reduce the potential for silage contamination of this important group of milk spoilage microorganisms by delaying the onset of aerobic deterioration.

Influence of cultivar, sowing date and maturity at harvest on yield, digestibility, rumen fermentation kinetics and estimated feeding value of maize silage

SUMMARYTwo maize hybrid cultivars, early (Cisko FAO 300) and late maturing (Arma FAO 700), were sown on three different dates (March, April or May) and harvested at two stages of maturity (kernel milk line (ML) scores of 1/4 &lt; ML &lt; 1/3 or 1/2 &lt; ML &lt; 2/3) in the western Po plain (Italy) in 2008. Yield, chemical composition andin vitrodigestibility and fermentation kinetics of pre-ensiled whole-crop maize and of silage were measured. Cultivar and sowing date influenced the dry matter (DM) yield of whole-plant maize, with DM yield being 40% higher in Arma than in Cisko, and DM yield decreasing with later sowing dates. Later maturity increased DM concentration at harvest for both hybrids, due to differences in kernel development. The neutral detergent fibre (NDF) content declined and starch increased as plants matured. Digestibility was estimatedin vitrofollowing the Ankom procedure. Rate and extent of ruminal degradation were estimated from gas production (GP) profiles during incubation in diluted rumen fluid. Cultivar, planting date and maturity had no effect onin vitroDM digestibility of pre-ensiled whole-crop maize, but following 240 days of ensiling significant differences between cultivars in digestibility were detected. GP kinetic parameters differed between cultivars for pre-ensiled whole-crop maize, with Cisko having higher asymptotic GP but lower fractional fermentation rates and longer lag times than the Arma hybrid. GP volumes were greater as sowing or harvest dates were delayed. Energy value and milk production were estimated using the Milk2006 Model. With the pre-ensiled whole-crop maize, a 38% greater milk yield/ha was expected with Arma than with Cisko, matching the 40% greater DM yield. The same trend was observed in maize silage, where cultivar and planting date affected milk production/ha, with greater values for Arma than for Cisko and lower values for the latest planting date. Optimal management practices, including decision making on planting and harvest time and hybrid cultivar selection, can influence the yield and nutritive value of maize silage.