Occurrence of mycotoxins in maize,grass and wheat silage for dairy cattle in the Netherlands

The occurrence of mycotoxins in 140 maize silages, 120 grass silages and 30 wheat silages produced in the Netherlands between 2002 and 2004 was determined using a liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS) multi-method. Deoxynivalenol (DON) was detected above the limit of quantification (LOQ) of 250 μg kg^?1 in 72% of maize and 10% of wheat silages. Average DON concentrations were 854 and 621 μg kg^?1, respectively, and maximum concentrations 3142 and 1165 μg kg^?1, respectively. Zearalenone was detected above the LOQ of 25 μg kg^?1 in 49% of maize and 6% of grass silages. Average zearalenone concentrations were 174 and 93 μg kg^?1, respectively, and maximum concentrations 943 and 308 μg kg^?1, respectively. The incidences and average concentrations of DON and zearalenone in maize silage were highest in 2004. The incidence of other mycotoxins was low: fumonisin B1 and 15-acetyl-DON were detected in 1.4 and 5% of maize silages, respectively, and roquefortin C in 0.8% of grass silages. None of the silages contained aflatoxins, ochratoxin A, T2-toxin, HT2-toxin, sterigmatocystin, diacetoxyscirpenol, fusarenon-X, ergotamine, penicillinic acid, or mycophenolic acid. This study demonstrates that maize silage is an important source of DON and zearalenone in the diet of dairy cattle. Since the carryover of these mycotoxins into milk is negligible, their occurrence in feed is not considered to be of significant concern with respect to the safety of dairy products for consumers. Potential implications for animal health are discussed.     

The effect of cellulase preparations on the chemical changes during the ensilage of grass in laboratory silos

Three experiments are described. In the first, cellulase prepared from Aspergillus niger was added at the rate of 4 g/kg to herbage treated with a variety of silage additives, formic acid, caproic acid, formalin, sodium metabisulphite and zinc bacitracin. The lowest cellulose contents and highest residual water soluble carbohydrate contents were found in the silages treated with formic acid and cellulase. Formic acid was included as a treatment in subsequent experiments. In the second experiment, the enzyme was added to herbage at two levels, 1.0 g/kg fresh grass and 4.0 g/kg fresh grass. Cellulose contents of the silages were significantly lower after 61 days at the higher rate of application of the enzyme. In the third experiment, two enzymes produced from Aspergillus niger were compared with two enzymes derived from Trichoderma viride. Under the conditions of the experiment the cellulase enzymes produced from T. viride were more active.     

Nutritive value of maize silage in relation to dairy cow performance and milk quality

Maize silage has become the major forage component in the ration of dairy cows over the last few decades. This review provides information on the mean content and variability in chemical composition, fatty acid (FA) profile and ensiling quality of maize silages, and discusses the major factors which cause these variations. In addition, the effect of the broad range in chemical composition of maize silages on the total tract digestibility of dietary nutrients, milk production and milk composition of dairy cows is quantified and discussed. Finally, the optimum inclusion level of maize silage in the ration of dairy cows for milk production and composition is reviewed. The data showed that the nutritive value of maize silages is highly variable and that most of this variation is caused by large differences in maturity at harvest. Maize silages ensiled at a very early stage (dry matter (DM) < 250 g kg^?1) were particularly low in starch content and starch/neutral detergent fibre (NDF) ratio, and resulted in a lower DM intake (DMI), milk yield and milk protein content. The DMI, milk yield and milk protein content increased with advancing maturity, reaching an optimum level for maize silages ensiled at DM contents of 300–350 g kg^?1, and then declined slightly at further maturity beyond 350 g kg^?1. The increases in milk (R² = 0.599) and protein (R² = 0.605) yields with maturity of maize silages were positively related to the increase in starch/NDF ratio of the maize silages. On average, the inclusion of maize silage in grass silage‐based diets improved the forage DMI by 2 kg d^?1, milk yield by 1.9 kg d^?1 and milk protein content by 1.2 g kg^?1. Further comparisons showed that, in terms of milk and milk constituent yields, the optimum grass/maize silage ratio depends on the quality of both the grass and maize silages. Replacement of grass silage with maize silage in the ration, as well as an increasing maturity of the maize silages, altered the milk FA profile of the dairy cows, notably, the concentration of the cis‐unsaturated FAs, C18:3n‐3 and n‐3/n‐6 ratio decreased in milk fat. Despite variation in nutritive value, maize silage is rich in metabolizable energy and supports higher DMI and milk yield. Harvesting maize silages at a DM content between 300 and 350 g kg^?1 and feeding in combination with grass silage results in a higher milk yield of dairy cows. © 2014 Society of Chemical Industry     

Fiber digestibility and protein value of pulp silage for lactating dairy cows: Effects of wet fractionation by screw pressing of perennial ryegrass

The aim of the study was to investigate the effects of substituting silage of chopped grass with pulp silage of grass fractionated once or twice in a biorefinery using a screw press on fiber kinetics, protein value, and production of CH₄ in dairy cows. Six lactating multiparous Holstein cows in mid-lactation (176 ± 93 d in milk), cannulated in the rumen, duodenum, and ileum, were used in an incomplete 6 × 4 Latin square design with a 2 × 3 factorial arrangement of treatments. Perennial ryegrass was harvested in third regrowth from the same field at early and late developmental stage (35 and 44 d of regrowth, respectively) and subjected to 1 of 3 types of processing within each developmental stage. Grass was either harvested for normal silage making (mowed, wilted, chopped, and ensiled), or harvested fresh and fractionated using a screw press. Half of the pulp from the first fractionation was ensiled, whereas the other half of the pulp was rehydrated, fractionated a second time, and pulp hereof was ensiled. The grass and pulp silages were used with concentrates (65:35 forage to concentrate ratio) to make total mixed rations (TMR) based on either silage of chopped grass (GS), pulp silage of grass fractionated once (1×P), or pulp silage of grass fractionated twice (2×P), harvested either at early (E) or late (L) developmental stage resulting in 6 different TMR treatments (EGS, E1×P, E2×P, LGS, L1×P, L2×P). The TMR were fed for ad libitum intake and samples of intestinal digesta and feces were collected for determination of digestibility. The effect of processing on ash-free neutral detergent fiber (aNDFom) concentration in silages depended on developmental stage, but showed that within each developmental stage, pulp silage of grass fractionated twice had higher aNDFom concentration than pulp silage of grass fractionated once and silage of chopped grass. The 2×P resulted in lower (14.9 ± 0.55 vs. 17.5 ± 0.54 kg/d) dry matter intake (DMI) compared with GS. The effects of processing and developmental stage interacted such that apparent total-tract aNDFom digestibility was higher (784 ± 13 vs. 715 ± 13 g/kg) for L2×P compared with LGS, whereas no difference was found between E2×P and EGS. Moreover, the protein value was higher (106 ± 5 vs. 92 ± 5 g AA digested in the small intestine/kg of DMI) for 2×P compared with GS. Unexpectedly, processing had no effect on fractional rate of digestion of digestible aNDFom or CH₄ yield (L/kg of DMI), whereas feeding forages harvested at early compared with late developmental stage resulted in lower CH₄ yield. Feeding pulp silage of grass fractionated once generally yielded results intermediate to cows fed silage of chopped grass and pulp silage of grass fractionated twice. This study showed that pulp silage of fractionated grass could serve as feed for dairy cows because the fiber digestibility and protein value improved, but further research investigating effects of physical processing of forage on fiber kinetics is required.     

The potential of sunflower as a crop for ensilage

The chemical composition and nutritive value of sunflower, cv. Armavirec, was examined at 12 stages of growth. Maximum yield of dry matter (18.2 t ha^?1) occurred at the dough seed stage. Ether extract showed a five-fold increase with the development of the seed. This increase was reflected in the gross energy value which was maximal at 19.1 MJ kg^?1 dry matter at the dough seed stage. In-vitro organic matter digestibility was highest at the onset of flowering when the estimated metabolisable energy value was 10.5 MJ kg^?1 dry matter. Throughout the sampling period the calcium to phosphorus ratios varied from 3.9-5.9:1, an imbalance which would have to be redressed on diets based largely on sunflowers. Fresh and wilted sunflowers were successfully ensiled at the flowering stage, without the use of additives. pH values of the resulting silages were 3.86 and 4.01. The silages were each fed to six cross-bred wethers and voluntary dry matter intakes were 23.9 and 26.5 g kgW^?1 for the fresh and wilted silages respectively. For the fresh silage, intakes of digestible organic matter and digestible nitrogen were 612 and 13.6 g day^?1 compared with 684 and 16.7 g day^?1 for the wilted silage. Nitrogen retention increased with increase in silage dry matter. The optimum time of cutting for yield of nutrients is at the milky ripe stage. The composition of the crop at this stage should facilitate a satisfactory preservation by ensiling. The crop provides a high yield of dry matter over about 10 weeks in late summer and could provide a valuable standby forage crop for grass in dry areas.     

Fermentation characteristics,aerobic stability and ruminal degradation of ensiled pea/wheat bi‐crop forages treated with two microbial inoculants,formic acid or quebracho tannins

This study evaluated the effects of two commonly used microbial inoculants (Lactobacillus buchneri (LB) and Lactobacillus plantarum (LP)), formic acid (FA) and quebracho tannins (QT) on the fermentation quality, aerobic stability and in situ rumen degradation of pea/wheat bi‐crop forages. Precision‐chopped spring pea (Pisum sativum, var Magnus) and wheat (Triticum aestivum, var Axona) bi‐crops (3:1 pea/wheat ratio) harvested at a combined dry matter (DM) content of 301 g kg^?1 were used for the study. The bi‐crops were conserved without (Control) or with inoculants based on lactic acid bacteria (LB (10⁵ CFU g^?1 fresh weight (FW)) or LP (10⁶ CFU g^?1 FW)), QT (16 g kg^?1 FW) or FA (2.5 g kg^?1 FW) in laboratory silos of 1.5 kg capacity, with each treatment being replicated six times. The pH, chemical composition, aerobic stability and in situ rumen degradation of DM, nitrogen (N) and neutral detergent fibre (NDF) after 112 days of ensilage were measured. The average pH at silo opening was 4.0, suggesting that the silages were well fermented. There were no significant effects of additive treatment on water‐soluble carbohydrate, total N, soluble N, ammonia N and NDF. Lactic acid and acetic acid were the main fermentation products. High concentrations of acetic acid were found in all the treatments, indicating a heterofermentative pathway. Although FA treatment gave the most aerobically stable silage, the Control and QT‐treated silages did not heat up by more than 1 °C until after 6 days of exposure to air. There were no effects of additives on DM degradation characteristics. However, the inoculants increased the rate of N and NDF degradation in the rumen, and both FA and QT reduced the effective and potential degradation of N. © 2001 Society of Chemical Industry     

Combined chemical and enzymic treatments of corn husk lignocellulosics

The potential for using corn (Zea mays L) husk residues (carbohydrates 827 g kg^?1, lignin 66 g kg^?1 DM) as a carbohydrate source for the production of soluble sugars by combined chemical pretreatment and enzymic hydrolysis was assessed. Comparative investigations of acidic and alkaline pretreatments on corn husk have shown that pentose-containing carbohydrates comprised 86–93% of the solubilised fraction. While pretreatments with 1.25 M NaOH at 25.85° C resulted in preferential extraction of hemicellulose having DP; > 12, acid pretreatments 0.51 M H₂SO₄, 0.51 M H₃PO₄ at (85° C) resulted in extensive depolymerisation of this polysaccharide. Xylose and low molecular weight carbohydrates were identified as the major products. Subsequent hydrolysis of the solubilised fraction with crude hemicellulase preparations yielded 40.90% fermentable sugars. When NaOH (0.02–1.25 M), H₂SO₄ and H₃PO₄ (0.02–0.51 M) were used as pretreatment solvents (25–85° C, 2 h), NaOH was the most effective in increasing the susceptibility of the residual husk towards enzymes, yielding 83–96% reducing sugars. This solvent solubilised up to 60.6% of the lignin and appeared to disintegrate the fibrillar structure of husk. The crystallinity of husk residues increased following the chemical pretreatments and was positively correlated with cellulose content. Enzymic hydrolysis with commercial cellulase preparations proceeded in two stages: a rapid breakdown of amorphous cellulose after which the hydrolysis rate levelled off. Similar biphasic patterns were observed for the pyrolysis temperature of cellulose. Under the most optimal conditions for husk saccharification (pretreatment with 1.25 M NaOH, 25° C, 2 h, followed by enzymic hydrolysis using a mixture of cellulase and cellobiase), 96% of the cellulose-enriched residues was hydrolysed to reducing sugars. A cellulase preparation from Trichoderma reesei exhibited substantial hemicellulolytic activity and could, therefore, be used as the sole saccharifying enzyme preparation for husk lignocellulosics.     

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.     

Ensilage as a means of reducing the concentration of cyanogenic glycosides in the pods of Acacia sieberiana and the effect of additives on silage quality

Cyanogenic glycosides are anti‐nutritional components capable of liberating hydrogen cyanide, a respiratory poison that has been reported to be responsible for the death of livestock that browse some Acacia species containing these compounds. The objective of the study was to improve the nutritive value of the pods of Acacia sieberiana by reducing their contents of cyanogenic glycosides through ensiling, and to examine the influence of various levels of added molasses and urea on the aerobic stability of the silage. In experiment 1, laboratory silages, prepared by mixing ground pods with water in two ratios (60:40 and 40:60 w/w pod material:water), were put into 250 ml polythene bottles, ensiled for 4, 7, 14, 21, 28 or 35 days and analyzed for cyanide. In experiment 2, silages prepared as described above but using only one of the ratios (40:60), and with the addition of molasses (0, 30 or 60 g kg^?1) and urea (0, 2.5 or 50 g kg^?1) were included in a 3 × 3 factorial design, to study the effects of these additives on the stability of the silage. The period of ensilage was 14 days. In experiment 3, the concentrations of molasses and urea were modified to 0, 45 or 90 g kg^?1 and 0, 7.5 or 15 g kg^?1, respectively, and the period of ensilage was extended to 45 days. The parent material contained 130.6 mg CN kg^?1 DM and ensiling the material for 35 days reduced the concentration to 18.1 mg CN kg^?1 DM. Moisture content at ensiling significantly (P < 0.001) affected the concentration of cyanide in the stored silages. Silages opened after 14 days were unstable irrespective of the use of additives. However those with combined urea and molasses exhibited a slow rate of deterioration and low fungal counts. Extending the period of ensiling to 45 days improved the aerobic stability of all the silages. The addition of urea significantly (P < 0.001) increased the pH, crude protein content, gross energy and fermentation acids while molasses treatment increased (P < 0.001) the lactic acid and ash content of the silages. Ensiling ground pods for 45 days was enough to reduce the cyanide content to non‐toxic levels and produced a silage which was aerobically stable, while the inclusion of additives further improved the quality of the silages. Copyright © 2004 Society of Chemical Industry     

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.     

Fermentation patterns in ryegrass,red clover and maize silages treated with formaldehyde additives at ensiling

The influence of level of formaldehyde application at ensiling on fermentation patterns in ryegrass, red clover and maize silages was studied in three experiments using small-scale silos. Formaldehyde was applied, together with formic acid at 2 litre t^?1 fresh crop, over the range 0 to 166 g formaldehyde kg^?1 crude protein (CP) in the crop. In ryegrass and red clover, but not in maize, low levels of formaldehyde application (<60 g kg^?1 CP) induced clostridial-type fermentations, as evidenced by increases in the content of volatile fatty acids and ammonia N. The concentrations of ethanol and 2,3-butanediol were also increased. At higher levels of application, formaldehyde was particularly effective in restricting fermentation in ryegrass and red clover silages, there being little acid production above 120 and 80 g kg^?1 CP, respectively. Only low levels of formaldehyde (ca 20 g kg^?1 CP) were required to achieve this effect in maize silage. In each crop the insoluble N content of the silages increased with level of formaldehyde application. The recovery of formaldehyde in both the treated herbage and silage improved with level of application, but did not exceed 50% of that applied. As physical losses of formaldehyde would be expected to be minimal under the conditions of the experiments, it appears that chemical bonding was the main reason for the lack of recovery of formaldehyde.     

The occurrence and prevention of ethanol fermentation in high‐dry‐matter grass silage

Ethanol is a common, usually minor fermentation product in ensiled forages, the major product being lactic acid. Occasionally, high levels of ethanol are found in silages. The aim of this study was to determine the incidence of high‐dry‐matter (DM) grass silages containing ethanol as the main fermentation product (ethanol silages), to describe the fermentation process in such silages and to determine the effect of grass maceration prior to wilting and addition of a bacterial inoculant containing Lactobacillus plantarum and Enterococcus faecium strains on fermentation. Twenty‐one laboratory silages produced between 1993 and 1995, 21 farm silages produced between 1980 and 1989 and 36 farm silages produced in 1995 (all produced without additive) were examined for pH and chemical composition. Dry matter (DM) loss during ensilage was determined for the laboratory silages only. Four laboratory silages were identified as ethanol silages. Mean concentrations of ethanol, lactic acid and acetic acid were 48.1, 15.5 and 6.0 g kg⁻¹ DM respectively. In the silages that contained lactic acid as the main fermentation product (lactic acid silages) these values were 7.7, 45.5 and 15.1 g kg⁻¹ DM. Mean DM loss and pH were 62.8 g kg⁻¹ DM and 5.32 respectively for ethanol silages and 24.4 g kg⁻¹ DM and 4.69 for lactic acid silages. There was no difference between ethanol silages and lactic acid silages in the mean concentration of ammonia‐N (94 g kg⁻¹ total N), and butyric acid was not detected (<0.2 g kg⁻¹ DM), indicating that both types of silages were well preserved. Analysis of the composition of the grass at ensiling showed a positive correlation between the concentration of soluble carbohydrates and the development into ethanol silage. Analysis of the farm silages indicated that 29% of the silages produced between 1980 and 1989 and 14% of those produced in 1995 were ethanol silages. Maceration prior to wilting and addition of silage inoculant improved lactic acid fermentation and prevented high ethanol levels. The micro‐organisms responsible for ethanol fermentation as well as the implications of feeding ethanol silages to livestock remain to be resolved. © 2000 Society of Chemical Industry     

Use of nitrification inhibitors to improve recovery of mineralised nitrogen by winter wheat

Nitrification inhibitors were applied in September 1980, after ploughing of a grass ley, to prevent formation of NO_3-N which could be lost by leaching and denitrification. Laboratory tests indicated that nitrapyrin or etridiazole at 1 μg g soil^?1 and dicyandiamide (DCD) at 10 μg g^?1 could inhibit nitrification by approximately 40%, compared with untreated soil, for 10 weeks at 10°C. In the field, nitrapyrin, etridiazole and DCD had little effect on NH₄ and NO₃ levels in the soil throughout autumn and winter. In April uptake of mineralised N by wheat was greater in plots treated with DCD (but not with nitrapyrin or etridiazole) than in untreated plots. Spring fertiliser N applications (35 or 70 kg N ha^?1) increased ear numbers, as did the two rates of all inhibitors except etridiazole. At harvest, grain and straw yields were increased by both rates of DCD with and without fertiliser N in spring, but there were no consistent increases from nitrapyrin or etridiazole. The mean increases in N uptake by wheat grain plus straw were 12 and 15% for 5 and 20 kg ha^?1 DCD respectively. DCD could be of use in preventing losses of NO₃-N, particularly in situations where large amounts of N may be mineralised during autumn and would be liable to loss prior to crop uptake.     

The effect of the addition of cell-wall degrading enzymes at ensiling on the response to postruminal supplementation of protein in dairy cows receiving a silage-based diet

Two silages were prepared from the same sward of perennial ryegrass. One was ensiled without additive and the other was ensiled with the addition of a mixture of cellulase and hemicellulase enzymes. Silage intake and milk production responses to the infusion of 230 g day^?1 into the abomasum were examined in four dairy cows in a 4 × 4 latin square design experiment with 14-day periods. The four treatments were (i)no-additive silage without casein, (ii) no-additive silage with casein, (iii) enzyme-silage without casein, and (iv) enzymesilage with casein. Both silages were given ad libitum with 5 kg day^?1 of a barley-soya bean meal mixture. Casein infusion tended (0.10 < P > 0.05) to increase the intake of the no-additive silage but the intake of the enzyme silage was unaffected. When casein was not given, the yields of milk and milk constituents were greater (P <0.05) for the enzyme-silage than for the no-additive control. Casein infusion increased (at least P <0.05) the yields of milk and milk protein with both silages but the increases were substantially greater with the no-additive silage; values were for milk yield (kg day^?1) 14.4 and 16.6 (no-additive), 15.9 and 16.8 (enzyme); and for milk protein yield (g day^?1) 464 and 558 (no-additive), 499 and 566 (enzyme) for the unsupplemented and casein treatments, respectively. The amino acid profile suggested that the supply of amino acids from the small intestine was greater with the enzyme-silage.     

Chemical and nutritional quality of silage made from raw or cooked lizard fish (Saurida undosquamis) and blue crab (Portunus pelagicus)

Twelve silages were prepared from uncooked or cooked lizard fish (Saurida undosquamis) and blue crab (Portunus pelagicus) and stored at ambient temperature (30 ± 2 °C) for 60 days. The antioxidative effect of adding ethoxyquin was also investigated. Generally, the nutritional quality of all the silages was stable for up to 60 days of storage and the composition of raw materials was reflected in the composition of the silages. Crab had a lower level of crude protein than fish (85 versus 162 mg kg^?1), but a higher level of ash (96 versus 36 g kg^?1); moreover, there were significant differences in nutritional composition between uncooked and cooked materials. High level of ash in crab required addition of high levels of formic acid in crab‐related silages. At the end of the experiment cooked silages showed a tendency for spoilage; in particular, maggots were observed in cooked crab silages on the last few days of the experiment. Comparison of treatments with or without ethoxyquin showed that only rancidity of fish silage groups was higher without addition of ethoxyquin. Uncooked materials are more suitable for prolonged storage than cooked materials, and it is probably not necessary to add antioxidants to silages made from material with low lipid content. Copyright © 2009 Society of Chemical Industry     

Sodium benzoate,potassium sorbate and sodium nitrite as silage additives

BACKGROUND: The hygienic quality of silage is important for animal health, animal production and food quality. The aim of this study was to evaluate the effect of five silage additive mixtures on yeast, mould, and clostridia growth and other silage quality criteria. The additives, composed of sodium nitrite, sodium benzoate and/or potassium sorbate, were used to treat a grass forage crop before ensiling. The silages were compared with untreated silage and silages treated with two commercial additives: Promyr NF (PNF), which is based on formic and propionic acid, and Kofasil Ultra (KU), a mixture of sodium nitrite, sodium benzoate, sodium propionate and hexamine. RESULTS: All tested additives significantly (P < 0.001) reduced butyric acid and ammonia‐N formation in low‐dry‐matter (DM) silages compared to the control. Only KU and the mixtures of 600 g sodium nitrite, 250 g sodium propionate, 750 g sodium benzoate (A1) and 250 g sodium nitrite with 1000 g sodium benzoate and 500 g potassium sorbate (A5) ton^?1 of fresh forage were found to reduce (P < 0.001) the presence of clostridia spores in low‐DM silages. In high‐DM silages, treatments A1, A5 and A2 (250 g sodium nitrite and 1000 g sodium benzoate) contained less (P < 0.02) yeast than the control and PNF, but not KU. All treated silages were aerobically stable. The concentrations of nitrate‐N in all silages and nitrite‐N in low‐DM were below the threshold level for feed at the end of storage. CONCLUSIONS: The additive mixtures A1 and particularly A5 improved silage quality at least to the same extent as commercial products, even though they contained no hexamine and less nitrite. Copyright © 2009 Society of Chemical Industry     

A meta-analysis of the effects of Lactobacillus buchneri on the fermentation and aerobic stability of corn and grass and small-grain silages

The results of adding Lactobacillus buchneri to silages from 43 experiments in 23 sources reporting standard errors were summarized using meta-analysis. The effects of inoculation were summarized by type of crop (corn or grass and small grains) and the treatments were classified into the following categories: 1) untreated silage with nothing applied (LB0), 2) silage treated with L. buchneri at ≤100,000 cfu/g of fresh forage (LB1), and 3) silage treated with L. buchneri at > 100,000 cfu/g (LB2). In both types of crops, inoculation with L. buchneri decreased concentrations of lactic acid, and this response was dose-dependent in corn but not in grass and small-grain silages. Treatment with L. buchneri markedly increased the concentrations of acetic acid in both crops in a dose-dependent manner. The numbers of yeasts were lower in silages treated with LB1 and further decreased in silages treated with LB2 compared with untreated silages. Untreated corn silage spoiled after 25 h of exposure to air but corn silage treated with LB1 did not spoil until 35 h, and this stability was further enhanced to 503 h with LB2. In grass and small-grain silages, yeasts were nearly undetectable; however, inoculation improved aerobic stability in a dose-dependent manner (206, 226, and 245 h for LB0, LB1, and LB2, respectively). The recovery of DM after ensiling was lower for LB2 (94.5%) when compared with LB0 (95.5%) in corn silage and was lower for both LB1 (94.8%) and LB2 (95.3%) when compared with LB0 (96.6%) in grass and small-grain silages.     

The use of pimaricin as an additive to improve the aerobic stability of silage

Pimaricin was added to samples from each of five crop species to give the following nominal rates of application: 0, 0.011, 0.022, 0.034, 0.045, 0.09 and 0.27 kg t^?1 fresh weight and the materials were ensiled in 100 g and 10 kg fresh weight quantities. Pimaricin applied at ensiling at 0.011 or 0.022 kg t^?1 reduced aerobic deterioration in three of the five crops—ryegrass, lucerne and tall fescue; a much higher rate of 0.27 kg t^?1 was required with silages made from red clover and maize. This beneficial effect occurred even though only from 1-66% of the pimaricin initially applied was recovered after the period of anaerobic storage in the silos. Pimaricin had no apparent effect on the course of fermentation nor on the composition of the silages, all of which were well preserved.     

Fate of Escherichia coli O157:H7 and bacterial diversity in corn silage contaminated with the pathogen and treated with chemical or microbial additives

Inhibiting the growth of Escherichia coli O157:H7 (EC) in feeds may prevent the transmission or cycling of the pathogen on farms. The first objective of this study was to examine if addition of propionic acid or microbial inoculants would inhibit the growth of EC during ensiling, at silo opening, or after aerobic exposure. The second objective was to examine how additives affected the bacterial community composition in corn silage. Corn forage was harvested at approximately 35% dry matter, chopped to a theoretical length of cut of 10 mm, and ensiled after treatment with one of the following: (1) distilled water (control); (2) 1 × 10⁵ cfu/g of EC (ECCH); (3) EC and 1 × 10⁶ cfu/g of Lactobacillus plantarum (ECLP); (4) EC and 1 × 10⁶ cfu/g of Lactobacillus buchneri (ECLB); and (5) EC and 2.2 g/kg (fresh weight basis) of propionic acid, containing 99.5% of the acid (ECA). Each treatment was ensiled in quadruplicate in laboratory silos for 0, 3, 7, and 120 d and analyzed for EC, pH, and organic acids. Samples from d 0 and 120 were also analyzed for chemical composition. Furthermore, samples from d 120 were analyzed for ammonia N, yeasts and molds, lactic acid bacteria, bacterial community composition, and aerobic stability. The pH of silages from all treatments decreased below 4 within 3 d of ensiling. Escherichia coli O157:H7 counts were below the detection limit in all silages after 7 d of ensiling. Treatment with L. buchneri and propionic acid resulted in fewer yeasts and greater aerobic stability compared with control, ECCH, and ECLP silages. Compared with the control, the diversity analysis revealed a less diverse bacterial community in the ECLP silage and greater abundance of Lactobacillus in the ECLP and ECA silages. The ECLB silage also contained greater abundance of Acinetobacter and Weissella than other silages. Subsamples of silages were reinoculated with 5 × 10⁵ cfu/g of EC either immediately after silo opening or after 168 h of aerobic exposure, and EC were enumerated after 6 or 24 h, respectively. All silages reinoculated with EC immediately after silo opening (120 h) had similar low pH values (<4.0) and EC counts were below the detection limit. The ECCH and ECLP silages reinoculated with EC after 168 h of aerobic exposure had relatively high pH values (>5.0) and EC counts (5.39 and 5.30 log cfu/g, respectively) 24 h later. However, those treated with L. buchneri or propionic acid had lower pH values (4.24 or 3.96, respectively) and lower EC counts (1.32 log cfu/g or none, respectively). During ensiling, EC was eliminated from all silages at pH below 4.0. During aerobic exposure, the growth of EC was reduced or prevented in silages that had been treated with L. buchneri or propionic acid at ensiling, respectively.     

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.