Chemical changes and losses during the ensilage of wilted grass

Two experiments were carried out; in the first, wilted Italian ryegrass at two different dry matter (DM) levels (34% and 47%) was ensiled; in the second, fresh grass (15.9% DM) and similar herbage wilted to 30.3% DM were ensiled. Total edible DM losses from the wilted silages were low and ranged from 6.7 to 10.4%. Changes in individual sugars and organic acids were followed. The residual amounts of sugars in the wilted silages were directly related to the degree of wilting. All silages were well preserved, but little fermentation had occurred in the material wilted to 47 % DM. From a knowledge of the sugars lost and amounts of mannitol and ethanol formed it has been possible to examine quantitatively the main chemical changes during the ensilage of the wilted materials. The results confirm the efficiency with which wilted grass is anaerobically conserved.     

Feeding value of silage: Silages made from freshly cut grass,wilted grass and formic acid treated wilted grass

Formic acid (850 g/kg) was added to wilted perennial ryegrass (dry matter = 360 g/kg) at the rate of 3.9 g/kg before ensiling. The feeding value of the resulting silage was compared with those of silages made from the wilted grass and the freshly cut grass, and with the grass itself in metabolism trials with sheep. Intakes of dry matter were depressed by fermentation, being 12.3, 9.7 and 8.5 g/kg liveweight for the acid treated, prewilted and directly ensiled material respectively. Fermentation improved the metabolisable energies which were 11.6, 12.0, 11.4 and 13.6 MJ/kg DM for the grass, and the acid treated, wilted and directly ensiled materials. In general, fermentation reduced the intake of metabolisable energy and the production potential of the material. The major factor affecting the feeding value of silage is its acceptability to the animal in terms of dry matter intake. High dry matter intakes are best achieved by limiting fermentation.     

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.     

The effect of delayed sealing on fermentation and losses during ensilage

In two separate experiments plastic silos were left opened to air for 3 days and then sealed. The composition of the resultant silages was compared with silages made in silos sealed immediately after filling. In the first experiment Lolium multiflorum of high water soluble carbohydrate (w.s.c.) content (27.3%) and low crude protein (c.p.) content (10.7%) was used and although variations in composition between the inside and outside layers of the “unsealed” silage occurred, both treatments produced well-preserved silage. In a second experiment using a later cut of similar grass but of low w.s.c. content (10.8%) and high c.p. content (23%), delayed sealing resulted in silages of high pH value with relatively high butyric acid and volatile N contents and low lactic acid levels. Dry matter losses during ensiling were also high in these aerated silages.     

甲酸处理后精纺毛织物耐磨性能及其纤维断裂端形态的变化

 羊毛织物经极性有机溶剂处理可以提高其耐磨性。在不同温度和时间下,选用甲酸对精纺毛织物进行处理,再经马丁代尔平磨仪摩擦处理10 000次后,对摩擦前后的织物进行称量。实验结果证明：若处理温度高于90 ℃,织物的质量损失会逐渐增大;而当处理时间是12 h, 处理温度为20 ℃时,织物的质量损失最小。另外,从磨损织物中选取适量的纤维进行扫描电镜观察发现,纤维断裂面主要呈现3种形态,即原纤化断裂面、圆形断裂面及横向断裂面,其中未处理样及低温处理后纤维的断裂面以原纤化断裂面居多,高温处理后以圆形断裂面居多。     

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.     

The effect of a cellulase preparation derived from Trichoderma viride on the chemical changes during the ensilage of grass,lucerne and clover

Perennial ryegrass, lucerne and clover were each treated with formic acid (4.5 litre t^?1 crop) and a commercial cellulase preparation derived from Trichoderma viride (4 g kg^?1) and ensiled in triplicate in test-tube silos, capacity 80 g. The crops were minced, finely chopped or coarsely chopped before ensiling and the test-tubes were held at 0, 15, 35 or 50°C. All the silages were well preserved and the grass silages, with and without cellulase treatment, contained residual water-soluble carbohydrates. Treatment with the cellulase preparation resulted in more cellulose being hydrolysed in the grass silages than in the legume silages. The greatest losses of cellulose in each crop occurred in the minced silages held at 15 and 35°C.     

A review of the changes in nitrogenous compounds of herbage during ensilage

In this review the major nitrogenous components of herbage have been identified and the effects of both plant and microbial enzyme activity on these components during the ensilage process have been described. In particular, the specific effects of the lactic acid bacteria and clostridia on amino acid degradation and the end products of such microbial activity are summarised. The effect of formaldehyde in preventing proteolysis is also discussed.     

Conservation of fresh and wilted grass in air-tight metal containers

Fresh and wilted timothy-meadow fescue herbage of 19 and 46.6° dry matter content, respectively, was ensiled in rubber-sealed steel cylinders 5 ft deep and 3 ft in diameter. Mean dry matter losses from all silos were about 6%. All silages were well preserved, the wilted material containing less lactic acid and volatile acids and having a higher pH. The dry matter digestibility coefficients from fresh and wilted grass silages were 71.5 and 70.2%, respectively, and were slightly higher than for the grass before ensilage. Ensilage resulted in a fall in metabolisable energy of the wilted grass. Intake of wilted silage by sheep was higher than that of silage from fresh grass.     

Lipid and protein changes during the ensilage of blue whiting (Micromesistius poutassou Risso) by acid and biological methods

Fish waste is a potential source of protein for animal nutrition. Ensilage could provide an advantageous means of upgrading these residues. Careful control of the degree of proteolysis and lipid oxidation is required to produce silages of high nutritional value. This paper studies the changes in lipids and protein during storage (15 days) of acid silages (with 0, 0.25 and 0.43%, w/w, of formaldehyde) and biological silages (with 10 and 20% molasses or dehydrated whey) prepared from blue whiting. A remarkable reduction in protein solubilisation values was achieved by adding formaldehyde. However, formaldehyde addition led to an increase in the peroxide value of the oil extracted from the silages. Ensiling by biological methods seems promising. It yielded both a considerable reduction in protein solubilisation and in basic volatile nitrogen when compared with acid ensilage. In addition, the oil from biological silages had lower peroxide values than the oil from acid silages with added formaldehyde.     

Effect of formic acid on the fermentation of grass of low dry matter content

Three experiments are described in which formic acid was added at different levels to low dry matter herbages. In the first and second experiments, using timothy/meadow fescue, the levels of acid used were 0·22% and 0·34% respectively, whereas in the third experiment, using cocksfoot, the concentration of acid was 0·51%. The immediate effect of the formic acid was to lower the pH values to 4·75, 3·81 and 4·11 in experiments 1, 2 and 3 respectively. Formic acid preserved water-soluble carbohydrates in the early stages of harvesting and ensiling but did not prevent the formation of lactic acid in experiments 1 and 3. Ethanol concentrations in the formic acid-treated materials in the first two experiments were higher than in the control silages. In all three experiments, the addition of formic acid did not reduce loss of dry matter and, in experiment 2, losses from the formic acid-treated herbage were higher than those from the control materials. This can be attributed mainly to the higher effluent production when formic acid was used. Changes in carbohydrates, nitrogenous components, organic acids and digestible nutrients are described.     

Changes during ensilage in the nitrogenous components of fresh and additive treated ryegrass and lucerne

The changes in the major nitrogenous components of herbage during the ensilage of lucerne and Italian ryegrass, with and without the addition of 85% formic acid and 40% formaldehyde at the rates of 3.2 and 7.4 g kg^?1 fresh herbage respectively, were studied. Both herbages were of similar amino-N composition except for asparagine which was about 10% of total nitrogen (TN) in lucerne and only 0.2% of TN in Italian ryegrass. After 90 days ensiling about 90% of the sum of protein-, peptide-, amino- and amide-N was preserved in the additive-treated silages while only 58% was recovered in the untreated lucerne (butyrate) silage. Recoveries of these compounds in the untreated ryegrass (lactate) silage was 83%. In the butyrate silage, the branched chain amino acids, valine, leucine and isoleucine were well preserved. In addition to these, proline, phenylalanine, glycine, methionine and threonine were well preserved in the lactate silages. Both the untreated silages contained more alanine than in their original respective herbages. Most of the losses from the amine-forming amino acids were recovered as their corresponding amines. Alpha-amino butyric acid and δ-amino valeric acid were found in both the untreated silages and the quantity present was dependent on the silage quality. In both the additive-treated silages, recoveries of amino acids, other than sulphur amino acids, lysine, histidine, tyrosine and tryptophan, were ca 90% or greater. The losses of these amino acids, excluding the sulphur amino acids, can be attributed mainly to the direct effects of formaldehyde in preventing their estimation following freeze drying or acid hydrolysis.     

Conservation of wilted and unwilted grass ensiled in air-tight metal containers with and without the addition of molasses

Italian ryegrass was ensiled in gas-tight silos in unwilted (21% dry matter) and wilted (42% dry matter) conditions without an additive and with the addition of molasses at a mean level of 8% in the dry matter. The total dry matter losses were 8·7, 7·2, 4·5 and 5·0% for unwilted, molassed unwilted, wilted, and molassed wilted grass silages respectively. The silages were all well preserved but the extent of fermentation had been reduced in the wilted silages. The losses of individual sugars during the silage process and the products of fermentation were used to assess the pathways of fermentation. The dominant pathway of fructose utilisation was by heterolactic fermentation. The addition of molasses reduced the ratio of fructose: glucose in the ensiled material and reduced the amount of mannitol produced during the ensilage process.     

Aflatoxin formation in hay treated with formic acid and in isolated strains of Aspergillus flavus

The possibility of improving the keeping qualities of field-dried and hayloft-dried hay, with dry matter contents of 55 and 73% by adding sodium chloride, formic acid and propionic acid was investigated. Field-dried, sodium-chloride-treated hay was stored in containers, while controls and acid-treated hay were pressed into high-density bales. All hayloft-dried hay was stored in containers. Fungal attacks were very heavy, especially in the baled hay. The contaminating flora was examined at the temperature maximum and after 40 and 32 days storage for field-dried and hayloft-dried hay respectively. The genera Penicillium, Cladosporium and Trichothecium were predominant in hayloft-dried hay, and the differences between varying dry matter contents were insignificant. Mostly Aspergillus spp., but also Penicillium spp., occurred in the field-dried hay at 73% dry matter content but at 55% the flora consisted mostly of Aspergillus flavus, and the formic acid-treated hay contained almost a pure culture of this fungus. In addition, aflatoxin B₁ and G₁ (635–1000 μg/l) were demonstrated in this formic acid-treated hay.

Toxin formation in isolates of A. flavus from differently treated hay specimens was also investigated on various substrates.     

草鱼冷藏过程中脂类的变化

采用GC-MS对草鱼脂肪中的脂肪酸进行分析,测定在4℃密封贮藏条件下,鱼肉脂肪中脂肪酸、脂肪酸氧化产物丙二醛和过氧化值的变化.鉴定出草鱼脂肪中含18种脂肪酸,其中饱和脂肪酸为29.30％,单不饱和脂肪酸为43.21％,多不饱和脂肪酸27.47％.C14～C17的脂肪酸在贮藏的前5d变化都不大,20碳以上的脂肪酸,到第5天已发生较大变化,到第10天各种脂肪酸的含量均明显下降,丙二醛、过氧化物含量随着贮藏时间延长急剧上升.     

Ascorbic acid losses during processing of French fries and potato chips

The fate of ascorbic acid during processing of French fries and potato chips was observed. Both products still contained a remarkable amount of ascorbic acid despite of losses during processing. A variety dependency was given. Main reduction was after blanching (French fries) and washing (potato chips). Especially in potato chips a high concentration of dehydroascorbic acid was detected.     

Ensiling characteristics and aerobic stability of direct‐cut and wilted grass silages inoculated with Lactobacillus casei or Lactobacillus buchneri

Two experiments were conducted to study the effects of wilting and inoculating Lactobacillus casei or Lactobacillus buchneri on the fermentation and aerobic stability of grass silages. Chopped Italian ryegrass (IR) and Festulolium (FE) were ensiled with or without wilting and added L casei (>10⁶ cfu g^?1 fresh matter (FM)) or L buchneri (>10⁶ cfu g^?1 FM). Silos were opened after 120 days and microbial counts, fermentation products and aerobic stability were determined. Addition of L casei increased lactic acid and decreased acetic acid and dry matter loss regardless of wilting and forage species. Inoculation of L buchneri decreased lactic acid and increased acetic acid and 1,2‐propanediol, while the effects appeared greater in direct‐cut than in wilted grass silages. Although 1,2‐propanediol accumulated in FE silage, the diol was degraded further to propionic acid and 1‐propanol in IR silage. The activity of 1,2‐propanediol degradation was lowered when IR was wilted prior to ensiling; 1,2‐propanediol remained and the production of propionic acid and 1‐propanol was less than one‐third of that in direct‐cut silage. Regardless of forage species, addition of L buchneri increased dry matter loss compared with the untreated control, whereas the loss was not significant in wilted silages. Ammonia production was increased by L buchneri in direct‐cut but not in wilted silages. No heating was observed with or without inoculation in direct‐cut IR silage after exposure to air. Other silages were deteriorated when L buchneri was not inoculated, while the spoilage was accelerated when L casei was added to FE. Copyright © 2005 Society of Chemical Industry     

Apparent digestibility of nitrogen in rumen and whole tract of Friesian cattle fed direct-cut and wilted grass silages

Spring grass consisting of Lolium perene L. (81%), Poa pratensis L. (9%), and annual weeds (5%) was stored as direct-cut or as wilted silage and used in feeding trials to determine the effects of wilting on N utilization. Six mature Friesian cattle, fitted with rumen and simple duodenal cannulae, were fed the silages for ad libitum intake in a crossover design consisting of two 49-d periods. Wilting increased intake of organic matter and decreased ruminal apparent digestibility or organic matter and whole tract apparent digestibilities of organic matter, NDF, and total N. Rumen degradability of silage N was increased by wilting (.7 vs. .67). Direct-cut silage, in comparison with wilted silage, provide (g/d) less N intake (232 vs. 286) and lower duodenal flows of total N (215 vs. 293), non-NH3 N (202 vs. 280), microbial N (111 vs. 177), and total amino acids (1056.8 vs. 1342.7). Duodenal flows of NH3 N and undegraded N were not different between silages. Efficiency of bacterial N synthesis in rumen was higher for wilted than for direct-cut silage (32.3 vs. 21.4 g N/kg organic matter apparently digested in rumen). It was concluded that wilting increase silage intake, rumen bacterial synthetic efficiency, and duodenal flow of non-NH3 N in cattle.     

Chemical changes occurring during the storage of black tea

The deterioration of black tea, characterised by a loss of flavour and astringency and sometimes by the acquisition of undesirable “taints” is accompanied by lipid hydrolysis and by autoxidative reactions that cause losses of theaflavins, amino acids, sugars, photosynthetic pigments and some volatile aliphatic constituents and increases in non-dialysable pigments and some volatile phenolic components. These reactions are accelerated by moisture and heat. Although lipid oxidation is insignificant except under hot dry conditions, it is postulated that oxidation of free fatty acids released during storage occurs during brewing, and has a profound influence on the quality of the liquor.