The influence of hydrochloric acid on the effect of caproic acid in preventing aerobic deterioration of silages

In five experiments of the same design using silages made from wilted Italian ryegrass (dry matter 22.7–40.9%), the effects of caproic acid (C₆) (10 mmol kg^?1) with and without 6_N-HCl (20 ml kg^?1), applied at ensiling or at opening, in preventing aerobic deterioration of silages after opening silos were investigated. Application of C₆ either at ensiling or at opening was partially effective in preventing temperature increase, pH rise and breakdown of organic acids during the 7-day aerobic exposure period after opening the silos. Addition of HCl reduced the pH of silages irrespective of the time of application. However, no improvement of the effect of C₆ due to HCl supplementation was observed as far as the prevention of the aerobic deterioration was concerned. Treatment with C₆+ HCl at ensiling inhibited silage fermentation more extensively than C₆ alone. Viable counts of yeasts and moulds in the silages treated with C₆ or C₆+ HCl at ensiling tended to be lower than those in the control silages. Considerable increases in the counts of moulds were found in the control silages during the aerobic exposure period.     

The effect of formalin and lower volatile fatty acids on silage fermentation

Lolium multiflorum was ensiled in 3 kg capacity PVC silos after treatment with formalin, formic acid, acetic acid and propionic acid applied singly and in mixtures of two, three and four at a constant application rate of 4.5 g kg^?1 fresh grass. The extent of fermentation was assessed by measuring pH, WSC, VN and TSN, and by microbiological analysis of total microorganisms and yeasts. The stability of the silages on exposure to air was measured using a specially constructed temperature recording apparatus. All additives restricted fermentation, although acetic acid and propionic acid were less effective than formalin, formic acid and mixtures of additives. The most aerobically stable silages were those treated with propionic acid, formic/acetic acids, and formic/acetic/propionic acids.     

Effect of added glucose and xylose on the fermentation of perennial ryegrass silage inoculated with Lactobacillus plantarum

Perennial ryegrass (Lolium perenne L) was ensiled in laboratory silos after addition of glucose or xylose at rates of 0, 25, 35 and 45 g kg^?1 fresh grass. In addition, an inoculum of Lactobacillus plantarum, supplying 10⁶ organisms g^?1 fresh grass, was applied to all treatments. Silos were opened after 7, 21 and 100 days and the silage was subjected to chemical and microbiological analysis. AH silages were well fermented with pHs between 3·60 and 3·70 and low NH₃-N concentrations (<95 g kg^?1 total nitrogen) and an absence of butyric acid. Glucose was virtually completely consumed within 21 days but 0·30–0·50 of the xylose doses remained after 100 days. Lactic acid concentrations were not increased by the addition of sugars, but the glucose treatments were associated with very high concentrations of ethanol, 60–100 g kg^?1 DM, and the xylose additions produced very high concentrations of acetic acid, 60–135 g kg^?1 DM. Most(>0·80) of the glucose that disappeared could be accounted for in ethanol formation but the xylose consumed could be accounted for only if the lactic acid produced in its fermentation was metabolised further to acetic acid; indeed, for the two higher doses of xylose, the concentrations of lactic acid were reduced from the control value of 177 g kg^?1 DM to 140 and 120 g kg^?1 DM, respectively. The results indicate that the provision of extra sugar, as hexose or pentose, allows yeasts to assume a more prominent role in the fermentation with consequent wasteful fermentation of sugars. Furthermore, the suggestion is that xylose may indirectly, via a stimulation of lactate-assimilating yeasts, encourage further metabolism of lactic acid to acetic acid.     

Conservation characteristics of wilted perennial ryegrass silage made using biological or chemical additives

The effects of 7 additive treatments on the fermentation and aerobic stability characteristics of wilted grass silage were studied under laboratory conditions. Treatments included no additive applied (untreated control), ammonium tetraformate at 3 and 6 L/t, homofermentative lactic acid bacteria alone (^hoLAB), a mixture of Lactobacillus buchneri plus homofermentative lactic acid bacteria (^he+hoLAB), and an antimicrobial mixture of sodium benzoate, sodium propionate, sodium nitrite, and hexamethylenetetramine at 2.5 and 5 L/t. Additives were compared across 3 consecutive harvests of 2 perennial ryegrass cultivars (AberDart and Fennema) following a 24-h wilt. Silos were opened after at least 100 d of ensilage and aerobic stability was assessed. Season of harvest had a large effect on grass composition at ensiling, producing herbages of relatively low (approximately 145 g/kg), medium (approximately 250 g/kg), and high (approximately 365 g/kg) dry matter (DM) concentrations. Within harvests there were lesser differences between cultivars. The untreated control and ^hoLAB additive produced badly fermented silage from the low-DM herbages and well-fermented silage from the medium- and high-DM herbages. The ammonium tetraformate treatments produced both well-fermented and badly fermented silage from the low-DM herbages depending on cultivar, and consistently well-fermented silage from the medium- and high-DM herbages. The ^he+hoLAB silages had similar or slightly lower standard of fermentation than the untreated and ^hoLAB silages. The antimicrobial mixture produced more silages of lower standard of fermentation than the untreated control and ammonium tetraformate and ^hoLAB additives. All additive treatments, including the untreated control, failed to consistently increase residual water-soluble carbohydrate concentrations at silo opening. Ammonium tetraformate at 6 L/t was the most successful and ^he+hoLAB the least successful additive at increasing residual WSC concentrations. The ^hoLAB silages were generally the least aerobically stable. Silages treated with ammonium tetraformate at 6 L/t were relatively stable under aerobic conditions. The ^he+hoLAB additive and antimicrobial mixture had an inconsistent effect on aerobic stability. Overall, ammonium tetraformate at 6 L/t was the most effective additive evaluated in this study, producing generally well-fermented silage with the highest concentrations of residual WSC and an intermediate to long duration of aerobic stability.     

The effect of decanoic,dodecanoic and tetradecanoic acids on silage fermentation

The ability of decanoic (C₁₀), dodecanoic (C₁₂) and tetradecanoic (C₁₄) acids to restrict the fermentation of ryegrass and lucerne was investigated with laboratory silos. With ryegrass, addition of the C₁₂ acid alone at 1 kg t^?1 of fresh crop had no effect on extent or pattern of fermentation compared to that of the untreated crop, though at 2 kg t^?1 the acid appeared to reduce the content of butyric acid but not ammonia-N in the silage. Formic acid, added alone or with C₁₀, C₁₂ and C₁₄ acids restricted extent of fermentation and butyric acid production, but in this experiment addition of these acids had relatively little effect on the content of ammonia-N in the silages. With lucerne, extent of fermentation was similar for all treatments, though the untreated silage and those which received C₁₂ or formic acid alone at 1 kg t^?1 or 1 kg t^?1 of C₁₄ acid with 1 kg t^?1 of formic acid contained butyric acid in excess of 3% of the dry matter (DM). It is concluded that acids in the range C₁₂-C₁₄ are not effective in restricting silage fermentation and that their effectiveness is not increased by reduction in pH produced by the addition of formic acid. Microbiological assessments largely confirmed these findings.     

Effect of applying inoculants with heterolactic or homolactic and heterolactic bacteria on the fermentation and quality of corn silage

This study examined the effect of applying different bacterial inoculants on the fermentation and quality of corn silage. Corn plants were harvested at 35% DM, chopped, and ensiled in 20-L mini silos after application of (1) deionized water (CON) or inoculants containing (2) 1 × 10⁵ cfu/g of Pediococcus pentosaceus 12455 and Propionibacteria freudenreichii (B2); (3) 4 × 10⁵ cfu/g of Lactobacillus buchneri 40788 (BUC); or (4) 1 × 10⁵ cfu/g of Pediococcus pentosaceus 12455 and 4 × 10⁵ cfu/g of L. buchneri 40788 (B500). Four replicates of each treatment were weighed into polyethylene bags within 20-L mini silos. Silos were stored for 575 d at ambient temperature (25°C) in a covered barn. After silos were opened, aerobic stability, chemical composition, and yeast and mold counts were determined. The DNA in treated and untreated silages was extracted using lysozyme/sodium dodecyl sulfate lysis and phenol/chloroform and used as a template for a conventional PCR with primers designed on the 16S rRNA gene to detect the presence of L. buchneri in all silage samples. Acetic acid concentration was greater in B2 silages versus others (6.46 vs. 4.23% DM). Silages treated with BUC and B500 had lower pH and propionic acid concentration and greater lactic acid concentration than others. The B500 silage had the greatest lactic:acetic acid ratio (1.54 vs. 0.41), and only treatment with BUC reduced DM losses (5.0 vs. 14.3%). Yeast and mold counts were less than the threshold (10⁵) typically associated with silage spoilage and did not differ among treatments. Consequently, all silages were very stable (>250 h). Aerobic stability was not improved by any inoculant but was lower in B500 silages versus others (276 vs. 386 h). The conventional PCR confirmed the presence of similar populations of L. buchneri in all silages. This may have contributed to the prolonged aerobic stability of all silages.     

An evaluation of laboratory ensiling techniques

Silages made from 18 grasses and 8 legumes in test-tube silos holding 100 g of fresh herbage were compared with those from the same crops ensiled in PVC bags holding 1 tonne of fresh material. For 8 herbages, polythene bags holding 6 kg of fresh material were also employed. Measurement of pH, ammonia-N, lactic acid and volatile acids was made at the end of the storage period (64–155 days). Measurements made on silages from the test-tube silos were closely correlated with those from the PVC bags. The correlation coefficients for ammonia-N (r = +0.978), acetic acid (r = +0.871), propionic acid (r = +0.850) and lactic acid (r = +0.639) were all significant at P < 0.001 and for butyric acid (r = +0.482) at P <0.05. Fermentations which occurred in polythene bags agreed closely with those in both the smaller test-tube silos and the larger PVC silos. There was good replication of silages from test tubes and polythene bags, the standard deviation for pH for the 26 silages made in test tubes was 0.144 with a coefficient of variation of 3.13%. The results indicate that laboratory silos have considerable potential in research, allowing a wider variety of crops and treatments to be studied than would have been possible on a larger scale.     

Effect of applying formic acid,heterolactic bacteria or homolactic and heterolactic bacteria on the fermentation of bi‐crops of peas and wheat

This work aimed to compare the effectiveness of bacterial inoculants or a chemical additive for preserving whole‐crop silages made from wheat, two pea varieties (cv Magnus or Setchey) or intercrops of wheat and both pea varieties. The forages were harvested when the wheat and peas were at the late milk and yellow wrinkled stages respectively, and conserved in five replicate mini silos without treatment (control) or after treatment with 2.5 g kg^?1 of formic acid (FA) or 1 × 10⁶ cfu g^?1 fresh forage of either of two bacterial inoculants (WholeCrop Gold (WCG) or WholeCrop Legume (WCL), Biotal Ltd, Cardiff, UK). WCG contained Lactobacillus buchneri, while WCL contained L buchneri, L plantarum and Pediococcus pentosaceus. Chemical composition, fermentation characteristics and in vitro digestibility were measured after 65 days of ensiling. Additive‐treated bi‐crops had lower (P < 0.05) concentrations of soluble N, ammonia N and lactic acid than the controls. Inoculant‐treated bi‐crops had higher (P < 0.001) acetic acid and lower (P < 0.001) residual water‐soluble carbohydrate (WSC) concentrations than FA‐treated bi‐crops. WCL‐treated bi‐crops had similar residual WSC concentrations to and higher (P < 0.05) starch concentrations than WCG‐treated bi‐crops. Unlike Magnus pea bi‐crops, Setchey pea bi‐crops treated with WCL had lower concentrations of ammonia N (P < 0.01) and acetic acid (P < 0.001) and higher concentrations of starch (P < 0.001) and lactic acid (P < 0.05) than those treated with WCG. For both bi‐crops, FA‐treated bi‐crops were more stable (P < 0.05) than inoculant‐treated or untreated silages, and the stability of inoculant‐treated and untreated silages was similar. Formic acid treatment was also the most effective at reducing WSC losses in the bi‐crop and pea silages. Inoculant treatment reduced proteolysis in these forages but did not prevent spoilage in the bi‐crops. Additive treatment reduced yeast counts but did not improve the fermentation in wheat silages. Copyright © 2004 Society of Chemical Industry     

Effects of a commercial inoculant of lactic acid bacteria on the composition of silages made from grasses of low dry matter content

The efficacy of a commercial inoculant, Natuferm, which contains multiple strains of lactic acid bacteria, was examined in seven experiments using 6 m³ pilot-scale silos. Samples taken during the fermentation period were analysed and compared with samples from untreated controls and formic acid silages. Good quality silages were obtained with crops of low dry matter content (12–14%) and with a water soluble carbohydrate content of 1·5% related to fresh weight. The addition of Natuferm resulted in increased lactic acid levels (50–90%) during the initial fermentation, and pH dropped faster compared with the untreated controls. Compared with the formic acid silages the level of enterobacteria declined rapidly in both the inoculated and untreated silages. In two of the experiments a pronounced difference in enterobacterial count was observed between the Natuferm and control silages on day 2. The effluent volumes were recorded, and the pH and the dry matter content of the effluent were determined. Compared with the formic acid silages, a 40% average reduction of the effluent flow was observed from Natuferm silages, and in most experiments there was also a reduced effluent volume compared with the controls. Analyses of 174 Natuferm silages and 73 formic acid silages from full scale (farm) silos revealed no significant differences in silage quality between the two additives. Natuferm silages with a dry matter content below 20% were not significantly different from silages with a dry matter content above 20%.     

The effect of sorbic acid on loss reduction during storage of orange peels

Sorbic acid (SA) at 0·25, 0·5 and 1·0 g kg^?1 was applied to fresh orange peels before ensiling in special 18 litre fermentation containers in two separate experiments. The higher two concentrations of sorbic acid were effective in reducing dry matter (DM) loss throughout the ensiling period, up to 90 days. Chemical analysis revealed that SA at the higher concentrations slowed down the fermentation rate, with less water-soluble carbohydrates (WSC) converted into organic acids and ethanol after 5 days of ensiling. However, after 30 and 90 days of ensiling, similar amounts of lactic acid were found in all silages, but less ethanol and more residual WSC were found in the silage treated with the higher SA concentrations. This indicates a more efficient fermentation pattern in the SA-treated silages. Microbial examination of the fresh and ensiled peels indicated large numbers of yeasts, the activity of which was probably inhibited by the sorbic acid.     

The effects of the rate of addition of formic acid and sulphuric acid on the ensilage of perennial ryegrass in laboratory silos

Perennial ryegrass was ensiled in laboratory silos after addition of formic acid (850 g kg^?1) or sulphuric acid (906 g kg^?1) at rates of 0, 2, 4 and 6 litres t^?1 fresh grass. Silos were opened after 6, 18 and 90 days and the silage subjected to chemical and microbiological analysis. The untreated control was poorly fermented with a final pH of 4.7, a butyric acid concentration of 19 g kg^?1 dry matter (DM) and an NH₃-N content of 275 g kg^?1 total nitrogen (TN). For the formic acid treatments the 2 litre t^?1 and 6 litre t^?1 levels both produced well-preserved silages but they were of different types. The silage treated with 2 litre t^?1 had a pH of 4.0, a lactic acid concentration of 92 g kg^?1 DM and 161 g NH₃-N kg^?1 TN, whereas with the 6 litre t^?1 treatment, fermentation had been severely restricted. The pH was 4.2, the lactic acid concentration was only 8 g kg^?1 DM and the NH₃-N content was 80 g kg^?1 TN. However, formic acid at 4 litre t^?1 produced a badly fermented silage of final pH 5.0 with lactic acid and butyric acid concentrations of 16 and 15 g kg^?1 DM, respectively, and an NH₃-N content of 149 g kg^?1 TN. Sulphuric acid at 2 and 4 litres t^?1 produced silages of low lactic acid contents, 36 and 24 g kg^?1 DM, and they also contained butyric acid in concentrations of 13 and 11 g kg^?1 DM; respective NH₃-N contents were 206 and 114 g kg^?1 DM. When sulphuric acid was added at 6 litres t^?1, despite a reduction in the pH of the grass to 3.5, fermentation was not restricted as it was with the equivalent level of formic acid. Lactic acid was present at 27 g kg^?1 DM and the ethanol concentration was very high at 66 g kg^?1 DM; the sulphuric acid-treated silages were characterised by high yeast counts. At the higher rates of addition, formic acid reduced the.     

Temperature during conservation in laboratory silos affects fermentation profile and aerobic stability of corn silage treated with Lactobacillus buchneri,Lactobacillus hilgardii,and their combination

The environment temperature and its effect on the temperature of silage is very important for the fermentation and subsequent quality of a silage. Obligate heterofermentative lactic acid bacteria (LAB) inocula, because of their ability to inhibit yeasts, have been developed to prevent the aerobic deterioration of silages. The temperature during silage conservation may also play an important role in the fermentation profile of silages. This study has evaluated the effect of temperature, during the conservation of whole crop corn silage, untreated or treated with different LAB inocula, on the fermentation profile and on the aerobic stability of the silage. Corn was harvested at 42% dry matter and either not treated (control) or treated with Lactobacillus buchneri NCIMB 40788 (LB) at 300,000 cfu/g fresh matter (FM); Lactobacillus hilgardii CNCM I-4785 at 150,000 cfu/g FM (LH₁₅₀); L. hilgardii CNCM I-4785 at 300,000 cfu/g FM (LH₃₀₀); or LB+LH at 150,000 cfu/g FM each. In an attempt to experimentally simulate temperature fluctuations in the mass or at the periphery of a silage bunker, corn was conserved in laboratory silos at a constant temperature (20 ± 1°C; MASS) or at lower and variable outdoor temperatures (PERIPH; ranging from 0.5 to 19°C), and the silos were opened after 15, 30, and 100 d of conservation. Lactic acid, acetic acid, and ethanol contents increased in all the silages over the conservation period. The lactic acid content was higher (+10%) in the silages kept at a constant temperature than those conserved at the lower and variable outdoor temperatures. The acetic acid was higher in the treated silages than in the control ones conserved at a constant temperature for 100 d. Moreover, 1,2-propanediol was only detected in the treated silages after at least 30 d at a constant temperature, whereas only traces were detected in the LB+LH treatment for the other temperature conditions. The yeast count decreased during conservation at a slower rate in PERIPH than in MASS and on average reached 2.96 and 4.71 log cfu/g for MASS and PERIPH, respectively, after 100 d of conservation. The highest aerobic stability values were observed for LH₃₀₀ (191 h) in the MASS silage after 100 d of conservation, whereas the highest aerobic stability was observed in LB+LH (150 h) in the PERIPH silages. After 7 d of air exposure, a pH higher than 4.5 and a higher yeast than 8.0 log cfu/g were detected in all the silages opened after 15 and 30 d of conservation. A pH value close to that of silo opening was detected in the LB, LH₁₅₀, and LH₃₀₀ silages conserved under MASS conditions after 100 d, whereas LB+LH was the most effective under PERIPH conditions. The temperature and its fluctuation during conservation of silage in laboratory silos influenced the fermentation, which in turn had an effect on the quality of silage and on the extent of the effect of LAB inocula.     

Resistance to aerobic deterioration of total mixed ration silage inoculated with and without homofermentative or heterofermentative lactic acid bacteria

Wet brewers grains were stored as a total mixed ration (TMR) in laboratory silos with lucerne hay, cracked maize, sugar beet pulp, soya bean meal and molasses at 5:1:1:1:1:1 on fresh weight basis. The TMR mixture was inoculated with or without Lactobacillus casei or Lactobacillus buchneri to obtain silages with differing fermentation and stability after exposure to air. In the first experiment, ensiling was stopped at 10, 20 and 60 days, and the stability was tested for the following 7 days. Ethanol and lactic acid were the main products in untreated TMR silage, while addition of L. casei and L. buchneri increased lactic and acetic acid, respectively. No silages deteriorated in the presence of air over 7 days, regardless of inoculation, ensiling period and the level of yeasts determined at unloading. In the second experiment, silos were opened at 14 days and then subjected to aerobic stability test for 14 days. Resistance to deterioration was sustained in the untreated control, even with a high population (>10⁴ cfu g^?1) of yeasts throughout the 14‐day test. Spoilage was found in L. casei‐treated silage at about 5 days, while increase of yeasts preceded the distinct heating (degradation). In L. buchneri‐treated silage, no yeasts were detected at unloading or after exposure to air. These results suggest that substantial stability can be expected in TMR silage with or without inoculation of lactic acid bacteria. This property is not associated with the counts of yeasts at loading and the characteristics of silage such as alcoholic and lactic acid fermentation. Copyright © 2007 Society of Chemical Industry     

The effects of various antifungal additives on the fermentation and aerobic stability of corn silage

In 2 consecutive years, whole plant corn was ensiled in laboratory silos to investigate the effects of various silage additives on fermentation, dry matter (DM) recovery and aerobic stability. In yr 1, chopped forage was treated with 1) no additive (untreated, U), 2) Lactobacillus buchneri40788, 4 × 10⁵ cfu/g of fresh forage (LLB4), 3) L. buchneri 11A44, 1 × 10⁵ cfu/g (PLB), 4) Biomax 5 (Lactobacillus plantarum PA-28 and K-270), 1 × 10⁵ cfu/g (B5), 5) Silo Guard II (sodium metabisulfite and amylase), 0.05% of fresh forage weight (SG), 6) a buffered propionic acid-based additive, 0.1% (Ki-112), 7), sodium benzoate, 0.1% of fresh weight (SB), or 8) potassium sorbate:EDTA (1:1), 0.1% of fresh weight (PSE). Silage treated with LLB4 had the highest concentration of acetic acid compared with other treatments, and yeasts were undetectable in LLB4 (<log₂ cfu/g). Silages treated with SB and PSE had the highest concentrations of water-soluble carbohydrates, the greatest recoveries of DM, and the lowest concentrations of ethanol. Silages treated with B5, SG, and Ki-112 had no effects on fermentation, DM recovery, or aerobic stability. The aerobic stabilities of silages treated with LLB4, SB, and PSE were greatest among all treatments. In yr 2, treatments were: 1) U, 2) LLB4, 3) PLB, 4) PLB at 4 × 10⁵ cfu/g (PLB4), and 5) B5. Silages treated with L. buchneri had greater concentrations of acetic acid but lower concentrations of ethanol than did U- and B5-treated silages. Yeasts were undetected in all silages except in silage treated with B5, which had the poorest aerobic stability of all treatments. Treatments had no effect on DM recovery. Silages treated with PLB, PLB4, and LLB4 remained stable for >210 h.     

Aerobic deterioration of lucerne (Medicago sativa) and Maize (zea mais) Silages—Effects of Yeasts

Lucerne (Medicago sativa L) silages made in test tube silos at various dry matter (DM) levels (290-537 g kg^?1) with and without addition of glucose (20 g kg^?1 herbage) at ensiling were stable during 7 days of aerobic exposure. Lucerne silages taken from seven farm silos were similarly stable while three others were unstable (average DM loss of 62 g kg^?1 DM and pH increase from 4.35 to 7.58 in 7 days). Under similar circumstances, maize (Zea mais L) silage had a high DM loss (164 g kg^?1 DM) and an increase in pH from 3.94 to 8.13. Silages were inoculated with yeast (1 × 10⁶ CFU g^?1 silage) isolated from aerobically deteriorating farm-scale lucerne and maize silages. The stable lucerne silages were not destabilised by inoculation, but the instability of unstable lucerne silages was increased. Aerobically unstable maize silage and stable lucerne silage were inoculated and studied separately or as a 50:50 mixture. There was a distinct lag in the development of aerobic instability in the mixture compared with maize silage alone. In another experiment, the growth of the inoculum in malt agar (pH 3.5) as affected by the presence of fresh and ensiled lucerne (six cultivars), birdsfoot trefoil (Lotus corniculatus L) and red clover (Trifolium pratense L) was studied. The legume herbages did not inhibit yeast growth whereas the corresponding silages did. Five aerobically stable lucerne silages inhibited yeast development in the media whereas unstable maize silage did not. It is concluded that aerobic stability was not related to silage DM, pH, yeast numbers or glucose addition at ensiling. Stability appeared to be due to the presence of an inhibitor (or inhibitors) produced during ensilage.     

Ozonated cotton stalks as a silage additive: Fermentation data on lucerne with particular reference to protein degradation

Fermentation patterns of lucerne silages were studied in laboratory silos. The treatments consisted of: (a) fresh (200 g kg>^?l DM) lucerne, ensiled without any treatment (L); (b) lucerne wilted to 525 g kg^?1 DM prior to ensilage (WL); (c) fresh lucerne + cotton stalks at a ratio of 60:40 on a dry matter (DM) basis (L + CS); and (d) fresh lucerne + ozone-treated cotton stalks at the same ratio as above (L+O₃). Silos were opened after 90 days and the silages analysed. The highest DM loss was found in the L silage (14·7%), whereas in the L+O₃ silage DM loss was practically nil. Both wilting and the addition of untreated cotton stalks proved to be effective in reducing DM losses during fermentation. The production of lactic acid and volatile organic acids in the L+ O₃ and WL silages was lower than in the L and L+CS silages. The poorest ability to preserve forage protein was found in the L silage, in which only 28 % of the protein was recovered after 90 days. The greatest ability to preserve protein was found in the L+O₃ silage, in which 78 % of the protein was maintained. Ammonia production followed generally similar patterns. Amino acids underwent extensive degradation in the L silage. Recovery of amino acids in the WL silage was in the range 69–93 %, and in the L + O₃ silage it was almost complete. Ozonated CS proved to be a good silage additive with respect to energy and protein preservation. Its future use in the field would allow direct ensilage of fresh leguminous material immediately after harvest, producing a high quality silage.     

Meta-analysis of effects of inoculation with homofermentative and facultative heterofermentative lactic acid bacteria on silage fermentation,aerobic stability,and the performance of dairy cows

Forages are usually inoculated with homofermentative and facultative heterofermentative lactic acid bacteria (LAB) to enhance lactic acid fermentation of forages, but effects of such inoculants on silage quality and the performance of dairy cows are unclear. Therefore, we conducted a meta-analysis to examine the effects of LAB inoculation on silage quality and preservation and the performance of dairy cows. A second objective was to examine the factors affecting the response to silage inoculation with LAB. The studies that met the selection criteria included 130 articles that examined the effects of LAB inoculation on silage quality and 31 articles that investigated dairy cow performance responses. The magnitude of the effect (effect size) was evaluated using raw mean differences (RMD) between inoculated and uninoculated treatments. Heterogeneity was explored by meta-regression and subgroup analysis using forage type, LAB species, LAB application rate, and silo scale (laboratory or farm-scale) as covariates for the silage quality response and forage type, LAB species, diet type [total mixed ration (TMR) or non-TMR], and the level of milk yield of the control cows as covariates for the performance responses. Inoculation with LAB (≥10⁵ cfu/g as fed) markedly increased silage fermentation and dry matter recovery in temperate and tropical grasses, alfalfa, and other legumes. However, inoculation did not improve the fermentation of corn, sorghum, or sugarcane silages. Inoculation with LAB reduced clostridia and mold growth, butyric acid production, and ammonia-nitrogen in all silages, but it had no effect on aerobic stability. Silage inoculation (≥10⁵ cfu/g as fed) increased milk yield and the response had low heterogeneity. However, inoculation had no effect on diet digestibility and feed efficiency. Inoculation with LAB improved the fermentation of grass and legume silages and the performance of dairy cows but did not affect the fermentation of corn, sorghum, and sugar cane silages or the aerobic stability of any silage. Further research is needed to elucidate how silage inoculated with homofermentative and facultative heterofermentative LAB improves the performance of dairy cows.     

Factors influencing aerobic deterioration of silages and changes in chemical composition after opening silos

In five separate experiments, silages made from Italian ryegrass by eight treatments were transferred into expanded polystyrene containers and the occurrence of deterioration was observed at 25–30 °C and 10–15 °C or 5–10 °C by measuring changes in temperature during 7 days. The treatments were: heavily wilted, slightly wilted, unwilted, and 2% glucose added to unwilted grass—all carried out with and without addition of 0.5% sodium propionate (in one experiment a mixture of 0.08% sodium nitrite and 0.04% hexamethylenetetramine was used instead). Silages tended to be less stable at 25–30 °C than at 10–15 °C ambient temperature, although some were stable even at the higher temperature. At 5–10 °C, no deterioration occurred. No definite relationship was found between occurrence of deterioration and the contents of dry matter or WSC in silage or density in the container. Although deterioration took place more often at pH lower than 4.0, no relationship between pH and deterioration was recognised in the range 4.0–7.0. Silages tended to be more stable when contents of total or lactic acid in fresh matter were high. Silages with no added propionic acid were more susceptible to deterioration but some were unstable even at high propionic acid levels. No aerobic deterioration took place with silages containing more than 0.5% butyric acid. With the deteriorated silages, rises in pH value (except for those with originally high pH), marked decreases in lactic acid and/or WSC were observed. Propionic acid content tended to remain constant in the stable silages but there were a few exceptions. Losses of WSC plus organic acids during deterioration were found to be higher with the silages of high WSC contents. Although changes with the stable silages were generally small, a few of them showed some decrease in WSC and/or organic acids.     

Effect of applying molasses or inoculants containing homofermentative or heterofermentative bacteria at two rates on the fermentation and aerobic stability of corn silage

This study determined how the fermentation and aerobic stability of corn silage are affected by treatment with molasses or 2 dual-purpose inoculants applied at or above the recommended rate. Corn forage (DeKalb 69-70) was harvested at 39% dry matter (DM) and ensiled after treatment with no additives (control, CON), molasses (MOL), Buchneri 500 inoculant, or Pioneer 11C33 inoculant. Molasses was applied at 3% of forage DM. Buchneri 500 was applied at the recommended rate of 8 mg/kg fresh forage to supply 1 × 10⁵ cfu/g of Pediococcus pentosaceus 12455 and 4 × 10⁵ cfu/g of Lactobacillus buchneri 40788 (BB) or at twice the recommended rate (DBB). Pioneer 11C33 inoculant was applied at the recommended rate of 1.1 mg/kg fresh forage to supply 1 × 10⁵ cfu/g of a mixture of Lactobacillus plantarum, L. buchneri, and Enteroccocus faecium (PN) or at twice the recommended rate (DPN). Each treatment was applied in quadruplicate and the treated forages were ensiled within 20-L mini silos for 135 d at 18 to 35°C. Molasses-treated silages had greater ash and starch concentrations than CON silages and greater lactate and ethanol concentrations than other silages. Like CON silages, MOL silages had high yeast counts (>10⁵ cfu/g); consequently, they deteriorated within 30 h as shown by temperature increase. Inoculant-treated silages had lower lactate to acetate ratios than CON or MOL silages largely because they had greater acetate concentrations. Consequently, all inoculant-treated silages had fewer yeasts (<10⁵ cfu/g) and were more stable (>30 h) than CON and MOL silages. When applied at recommended rates, PN and BB had similar effects on silage chemical composition, fermentation, fungal counts, and aerobic stability, except for a lower lactate concentration in PN silages. Concentrations of VFA, and NH₃-N, pH, and extent of aerobic stability were similar for PN, DPN, BB, and DBB silages. However, lactate concentration was greater in DPN than in PN. In conclusion, MOL application increased ethanol and lactate concentration and did not improve aerobic stability. Both dual-purpose inoculants made the fermentation more heterolactic and thereby improved the aerobic stability of corn silage. Doubling the rate of application of either inoculant did not further improve fermentation or aerobic stability.     

Inoculant effects on alfalfa silage: fermentation products and nutritive value

The effect of 14 microbial inoculants on the fermentation and nutritive value of alfalfa silages was studied under laboratory conditions. The first cut (477 g of dry matter/kg) and second cut (393 g of dry matter/kg) of a second-year alfalfa stand were ensiled in 2 trials. In both trials alfalfa was harvested with standard field equipment. All inoculants were applied at 1.0 × 10⁶ cfu/g of crop. Uninoculated silages served as controls. After inoculants were added, the chopped forages were ensiled in 1.0- and 0.5-L anaerobic glass jars, respectively, at a density of 500 g/L. Each trial had 15 treatments (uninoculated control and 14 inoculants), with 4 silos per treatment. Silos were stored for a minimum of 30 d at room temperature (∼22°C). In first-cut silage, all inoculants but one reduced pH relative to the uninoculated control, and all but 2 of the homofermentative strains shifted fermentation toward lactic acid. In second-cut silage, the epiphytic lactic acid bacterial population was 2.7 × 10⁷ cfu/g, and only commercial inoculants produced significant shifts in fermentation. Overall, microbial inoculants generally had a positive effect on alfalfa silage characteristics in terms of lower pH and shifting fermentation toward lactic acid with homofermentative lactic acid bacteria or toward acetic acid with heterofermentative lactic acid bacteria, Lactobacillus buchneri. These effects were stronger in the commercial products tested. In spite of the positive effects on silage fermentation, 48-h in vitro true DM digestibility was not improved by inoculation with lactic acid bacteria.