Seasonal changes in the crude protein concentration of mixed swards of white clover/perennial ryegrass grown without fertilizer N in an organic farming system in the United Kingdom

Changes in the crude protein (CP) concentration of white clover and perennial ryegrass herbage from a mixed sward were determined on six sampling dates from May to October in each of 2 years. The swards were grown without fertilizer N in an organic farming system and continuously grazed by dairy cows during the grazing season. The annual mean contents of white clover in the dry matter (DM) of the sward were 272·3 and 307·0 g kg⁻¹ in Years 1 and 2. The mean CP concentrations of the white clover and perennial ryegrass herbage were 251·6 and 151·9 g kg⁻¹ DM in Year 1 and 271·9 and 174·0 g kg⁻¹ DM in Year 2 respectively. The CP concentration of the white clover increased significantly during the grazing season from 220·0 to 284·1 g kg⁻¹ DM in Year 1 and from 269·0 to 315·5 g kg⁻¹ DM in Year 2. In the perennial ryegrass herbage the CP concentration increased from 112·2 to 172·6 g kg⁻¹ DM in Year 1 and from 142·7 to 239·5 g kg⁻¹ DM in Year 2. The rate of increase during the season in the CP concentration of the perennial ryegrass herbage was similar to the rate of increase recorded in the white clover herbage.     

A note on ensiling safflower forage

Abstract The ensiling characteristics of safflower ( Carthamus tinctorius ) wilted to 290 and 411 g dry matter (DM) kg⁻¹ fresh material were studied in 1·5 l glass jars. The experiment included a control and the application of Lactobacillus plantarum at 3·3 × 10⁵ colony-forming units (cfu) per g of crop. After 60 days of ensiling, the pH of safflower silages was 4·6 and 4·0 in the control and inoculated silages respectively, with corresponding values for lactic acid, the major fermentation product, of 20 and 45 g kg⁻¹ DM. The silages from the anaerobic jars were stable upon aerobic exposure. It is concluded the safflower silage has potential as an alternative fodder in semiarid regions.     

Fermentation characteristics and aerobic stability of grass silage inoculated with Lactobacillus buchneri, with or without homofermentative lactic acid bacteria

Aerobic spoilage by yeasts and moulds is a major cause of reduced nutritional value of silage and increases the risk of potential pathogenic microorganisms. Recent studies have shown that inoculation with Lactobacillus buchneri inhibits yeast growth and reduces the susceptibility to aerobic spoilage of various ensiled forages. The aim of this study was to determine whether these effects are retained when L. buchneri is added in combination with homofermentative lactic acid bacteria. In three experiments, silages were produced from perennial ryegrass [240–421 g kg⁻¹ dry matter (DM)] inoculated with L. buchneri or L. buchneri plus a mixture of Pediococcus pentosaceus and Lactobacillus plantarum (inoculant PL). Uninoculated silage and silage inoculated with PL alone served as controls. Silages were examined for pH and DM loss in the course of ensilage and chemical and microbiological composition and aerobic stability after 3–4 months. L. buchneri plus PL and PL alone increased the initial rate of pH decline. L. buchneri alone and L. buchneri plus PL enhanced aerobic stability and, in general, reduced yeast and mould counts. In addition, these inoculants increased the final pH and DM loss and the concentrations of acetic acid and 1,2-propanediol (or propionic acid and 1-propanol instead of 1,2-propanediol), and decreased the concentration of lactic acid. The effects of L. buchneri on fermentation products increased with decreasing DM content. In silages of less than 270 g kg⁻¹ DM, L. buchneri increased the ammonia-N concentration. It is suggested that this was associated with the relatively high final pH resulting from the high metabolic activity of L. buchneri in these silages.     

Effect of herbage water-soluble carbohydrate content and weather conditions at ensilage on the fermentation of grass silages made on commercial farms

A total of 1009 samples of silage made in bunker silos on commercial farms between 1972 and 1978 was analysed to investigate the effect of herbage water-soluble carbohydrate content (WSC) and weather conditions at ensilage on fermentation as measured by ammonia-N concentration and pH of first-cut grass silages.
Silage dry matter (DM) content had the major effect on fermentation. Factors influencing silage DM were rainfall and hours of sunshine during silage making, and DM content of the grass cut. WSC content of herbage ensiled also had a significant effect on subsequent fermentation. The major influences on herbage WSC were hours of sunshine and rainfall during the growing season.
The effect of chemical additives, albeit at poorly defined and often inadequate rates, was small in comparison to that of silage DM.
The minimum DM necessary to produce well-fermented silage without additive was approximately 260 g kg⁻¹. Use of formic acid significantly reduced this requirement to 240 g kg⁻¹ and to 252 g kg⁻¹ for sulphuric add + formalin. The results indicate that the minimum herbage WSC necessary to prevent a clostridial fermentation developing in silage with a DM content of 230 g kg⁻¹ is approximately 37 g kg⁻¹ without additive and 30 g kg⁻¹ with formic acid.
It is concluded that on commercial farms, weather conditions i.e. amount of rainfall and sunshine prior to and at ensilage, have a greater effect on subsequent silage fermentation than additive use.     

The digestion by cattle of grass silages made with no additive or with the application of formic acid or formic acid and formaldehyde

The aim of the experiment was to assess the effect of applying, at commercially recommended rates, formic acid or formic acid/formaldehyde at ensilage upon the subsequent digestion of the silages by cattle. Three wilted grass silages were made from perennial ryegrass ensiled at a DM concentration of 206 g kg⁻¹ after a poor wilting period of 49 h without additive application and with application of 2.5 litres t⁻¹ of formic acid or of 4.5 litres t⁻¹ of a mixture of (gkg⁻¹) 500 formic acid, 200 sulphuric acid and 200 formatin giving an application rate of 15 g formaldehyde kg⁻¹ herbage crude protein (N × 6.25).
The silages were fed to cattle equipped with rumen cannulae and duodenal re-entrant cannulae. Results from analyses of silage composition and from the digestion of organic matter and N showed no major differences between silages. The efficiency of rumen microbial N synthesis, the rumen degradability of silage N (determined in vivo or in sacco ) and in vivo digestion of individual amino acids were also unaffected by additive treatment. These results indicate that poor wilting conditions before ensilage restricted the effectiveness of additive treatment; the ineffectiveness of formaldehyde in reducing the rumen degradability of silage N may also have been related to the low rate of formaldehyde application.     

Effect of stage of maturity of whole-crop barley on intake and liveweight gain by dairy steers differing in initial live weight

The effect of maturity at harvest of whole-crop barley for ensiling on intake and liveweight gain of dairy steers differing in initial live weight (LW) was evaluated in an experiment over two years. Light (104–120 kg) and heavy (402–419 kg) dairy steers were fed diets containing predominantly whole-crop barley silage harvested at the milk stage [dry matter (DM) content of 284 g kg⁻¹ and neutral-detergent fibre (NDF) concentration of 526 g kg⁻¹ DM] or the dough stage of maturity (DM content of 328 g kg⁻¹ and NDF concentration of 445 g kg⁻¹ DM) and supplemented with up to 1 kg of concentrate. Dry matter intake (g kg⁻¹ LW) was higher for whole-crop barley harvested at the dough stage than at the milk stage of maturity and the difference was greater in heavy than in light steers ( P <  0·001). Liveweight gain was higher and feed conversion ratio was lower for dough-stage compared with milk-stage silage ( P  <   0·05) but there was no interaction with size of steer. Whole-crop barley harvested at the dough stage of maturity promoted higher liveweight gains in dairy steers compared with whole-crop barley harvested at the milk stage due to a higher DM intake.     

The effect of dry matter content on the preservation of big hale grass silages made during the autumn on commercial farms in South Wales 1983-87

A total of eighty-nine big-bale (BB) silages made on commercial farms in South Wales during the autumn in 1983-87 were analysed to discern the effect of dry matter (DM) content on fermentation. Silages were made predominantly in late September, during fine weather from permanent pasture or perennial ryegrass pastures, which had not been grazed for 9 weeks. On average 7·8 ha of pasture were cut; most farmers attempted to pre-wilt grass for an average of 36 h prior to ensilage in individual plastic bags. Silage making was usually completed within 4 d of starting to cut. Silage ammonia-N content was inversely correlated with DM content. The results indicated that a DM content of about 280 g kg⁻¹ was needed to produce well-preserved silage with an ammonia-N content of 100 g (kg total N)⁻¹. Silages were, therefore, generally poorly preserved because the DM increase from wilting was only 2·3 g kg⁻¹ h⁻¹.     

A comparison of unwilted and wilted grass silages offered to beef cattle without and with monensin sodium

A randomized block experiment was conducted to compare unwilted and wilted grass silages and the effects of the feed additive monensin sodium on the silage intake and performance of finishing beef cattle. Two regrowths from a predominantly perennial ryegrass (cv. S24) sward were ensiled either without wilting or after field wilting for 3 d (dry matter (DM) concentrations 161 and 266 g kg⁻¹ respectively). Both silages were treated with formic acid (2·6 and 30 litre t⁻¹ respectively) and were well preserved. The silages were offered ad libitum to forty-eight Charolais-cross cattle (thirty-two steers and sixteen heifers, mean initial live weight 351 kg) for 145 d. All animals received 2·2 kg concentrates per head daily and half of those on each silage treatment received in addition 200 mg monensin sodium per head daily. Silage DM intake was 5.04, 504. 5·48, 5·63 ± 0.134 kg d^−l; fasted liveweight gain was 0·69, 0·77. 0·64 and 0·73 ± 0.033 kg d^−l and carcass gain was 0·47, 0·50, 0·40 and 0·45 ± 0·020 kg d⁻¹ for the unwilted silage without and with monensin and the wilted silage without and with monensin respectively. It is concluded that wilting grass of low DM concentration for 3 d prior to ensiling reduced the performance of finishing beef cattle below that obtained from well-preserved unwilted silage in spite of a higher DM intake being achieved with the wilted silage. The inclusion of monensin sodium in a silage-based diet increased performance without significantly affecting feed intake.     

Silage and milk production: studies with diets containing white clover silage

In three separate feeding experiments using a total of twenty-six individually-housed Ayrshire cows, three wilted silages made from Blanca white clover were offered ad libitum with either different supplements or different proportions of grass silage. The clover silages contained 680 g white clover kg⁻¹ on a DM basis, and had a mean DM concentration of 263 g kg⁻¹ with 231 g CP kg⁻¹ DM and 91 g ammonia-N kg⁻¹ N. The pH values averaged 4·16 and the DOMD concentrations 611 g kg⁻¹. In experiment 1 the daily intake of clover silage given alone was 15.2 kg DM per cow, i.e. 30·1 g kg⁻¹ live weight, and decreased by 0·76 kg DM kg⁻¹ barley DM and by 0·66 kg DM kg⁻¹barley plus soybean meal DM when these feeds were offered as supplements. Milk yield and fat concentration were higher on the supplement treatments than on the clover silage-only treatment. In experiments 2 and 3 the intakes of silage and total DM increased as the weight of clover in the diet increased from 0 to 700 g kg⁻¹ with parallel increases in milk yield. The effects on milk composition were small and generally non-significant. Although white clover silages with excellent fermentations were made, it is concluded that the main role of white clover in a silage system will be in mixed swards with grass to reduce the input of fertilizer N and to increase the voluntary intake of silage.     

Ensiling of manured crops—effects on fermentation

The quality of silage from crops fertilized with cattle manure and an inorganic fertilizer was compared in experiments from 1985 to 1989. Manure was spread either as farmyard manure (FYM, 25t ha⁻¹) or as slurry (20-50t ha⁻¹). Crops were direct cut (approximately 200 g DM kg⁻¹) or wilted (approximately 300 g DM kg⁻¹), precision chopped and ensiled in experimental silos. Silage was treated with 4 kg 85% fonnic acid t⁻¹ fresh matter (FM), an inoculant or no additives. The use of manure, particularly FYM, resulted in more Bacillus spores on crops at harvest compared with fertilized crops. Clostridium spores increased as a result of manuring in 1989 only on FYM-treated crops. Differences in the chemical composition of crops were usually small between fertilizer treatments. The quality of silage from slurry-dressed crops, compared with that of silage from fertilized crops, varied between years. The FYM resulted in reduced silage quality, i.e. high pH values (> 4·5), high ammonia N (> 150 g kg⁻¹ total N) and butyric acid (> 6·3 g kg⁻¹ water) concentrations, and high numbers of Bacillus (10⁵ g⁻¹ FM) and Clostridium spores (10⁵ g⁻¹ FM). The concentration of lactic acid was low (≤ 12 g kg⁻¹ water). Wilting and additives generally improved silage quality and reduced the differences between treatments. However, the efficiency of the inoculant on farmyard manured crops was limited.     

A study of the efficacy of a bacterial inoculant and formic acid as additives for grass silage in terms of milk production

In a two-year experiment, three silages were prepared from herbage treated either with an inoculant at 1·25 × 10⁵ organisms (g fresh material (FM))⁻¹. formic acid (850 g kg⁻¹) at 4 1 (t FM)⁻¹, or no additive (untreated). In Experiment 1, unwilted and in Experiment 2, wilted silages were investigated and had mean dry matter (DM) and water soluble carbohydrate (WSC) concentrations at ensiling of 171 g kg⁻¹ and 17·6 g (kg FM)⁻¹ and 263 g kg⁻¹ and 25·1 g (kg FM)⁻¹, respectively. In Experiment 1, 45 and in Experiment 2, 54 individually fed cows were used to evaluate the silages in three-treatment, randomized-block design experiments. During weeks 4-12 of lactation the cows were offered silages ad libitum and during weeks 15-26 a constant amount of silage was fed. There were few major differences in chemical composition of the resulting silages. Formic acid had no effect on silage digestibility. Inoculant treatment increased digestibility when the grass had been wilted. The use of formic acid resulted in increased silage DM intake of 9% during weeks 4-12 of lactation in Experiment 1 but not in Experiment 2. The inoculant gave no increase in silage DM intake over the control in Experiment 1 but increased silage DM intake by 7% in Experiment 2. There was no significant response in milk yield to formic acid. In Experiment 2 the response in milk yield to inoculant treatment was significant both in weeks 4-12 of lactation (4%) and in weeks 15-26 of lactation (5%). It is concluded that the response in milk yield to the use of a specific inoculant appears to be mediated through increased intake of metabolizable energy (ME).     

Silage and milk production: studies with molasses and formic acid as additives for grass silage

In two separate feeding experiments using a total of twenty-four individually housed Ayrshire cows six silages made from perennial ryegrass were offered ad libitum with supplements of concentrates. In Experiment I herbage with a dry matter (DM) concentration of 225 g kg⁻¹ received either formic acid ('Add-F') at the rate of 2·0 litres t⁻¹ or undiluted cane molasses at rates of 10, 20 and 30 litres t^−l; the mean daily silage intakes were 9·54, 908, 9·27 and 9·49 kg DM per cow and the daily milk yields, corrected to 40 g fat kg⁻¹, were 23·2, 22·3, 22·8 and 22·9 kg per cow respectively but none of the differences between the four treatments was significant. In Experiment 2 herbage with a DM concentration of 269 g kg⁻¹ received formic acid at a uniform rate of 2·6 litres t⁻¹ either with or without an additional application of molasses at 20 litres t⁻¹; the mean daily silage DM intakes were 8·70 and 9·28 kg per cow and the daily fat-corrected milk yields were 22·2 and 21·9 kg per cow respectively and were not significantly different. In both experiments the effects of the treatments on milk composition were small and not significant. It is concluded that there were no advantages in applying molasses to herbage treated with formic acid, and that the rate of application of molasses to untreated herbage which equated with the formic acid application was 20·30 litres t^−l when assessed on the basis of silage composition, intake and milk production.     

The effect of an acid salt-type additive on the fermentation of grass silages made in bunker silos on commercial dairy farms in Wales

The fermentation characteristics and chemical composition of 57 first-cut and 30 second-cut samples of grass silages, made in bunker silos on commercial dairy farms in Wales in 1990, and treated with a nominal 61 t⁻¹ of an acid salt-type additive at ensilage, is described. Typical chemical composition of grass cut for ensilage was 156 g kg⁻¹ dry matter (DM) and 28 g kg⁻¹ water soluble carbohydrate (WSC), with 181 g (kg DM) ⁻¹ crude protein (CP) and 232 g (kg DM) ⁻¹ modified acid detergent fibre (MADF). The effect of additive use was to produce silages with DM 230 g kg⁻¹ pH 3·93, ammonia N 70 g kg⁻¹ total N, with residual WSC 35 g (kg DM) ⁻¹, lactic acid 83 g (kg DM) ⁻¹, total acids 118 g (kg DM) ⁻¹ and butyric acid 0·7 g (kg DM) ⁻¹. No significant differences were found between first- and second-cut silages. Silage fermentation was restricted (i.e. lactic acid less than 60 g kg DM⁻¹) in only 20% of the samples.
It is suggested that on commercial farms the application rate achieved may be insufficient to produce a restricted fermentation.     

Enzymes as silage additives for grass–clover mixtures

Seven laboratory-scale experiments were carried out to study the effects of cellulases/hemicellulases on silage fermentation of herbage from mixed swards of timothy ( Phleum pratense ), meadow fescue ( Festuca pratensis ) and red clover ( Trifolium pretense ). Enzyme-treated silage (approximately 3500 HEC units kg⁻¹ grass) reached a low pH sooner, had lower end pH, contained less NH₃-N and more lactic acid than did the untreated silage ( P < 0·05). Applied with an inoculant, these effects were even stronger. With easily ensiled crops (experiments 1, 2, 5 and 6) preservation was first of all improved by inoculation of lactic acid bacteria; however, for the low-sugar crops (experiments 3, 4 and 7) enzyme treatment was more significant. The enzymes derived from Aspergillus spp. gave more acetic acid than the enzymes from Trichoderma reesei. The Trichoderma enzymes liberated 4·8 g WSC kg⁻¹ FM gamma-irradiated grass during 60 d at pH 4·3 ( P < 0·05). On average, for all silages enzyme treatment increased the sum of residual sugar and fermentation products by 3·7 g kg⁻¹ FM (21 g kg⁻¹ DM) compared with the silages not treated with enzymes ( P < 0·001). Enzyme treatment increased the instantly degradable part of the feed, but total in sacco and in vitro digestibilities were not affected.     

Proteolysis and amino acid degradation during ensilage of untreated or formic acid-treated lucerne and maize

Lucerne ( Medicago sativa ), field wilted to 330 g dry matter (DM) kg⁻¹, and whole-plant maize ( Zea mays ), 383 g DM kg⁻¹, were treated with formic acid (FA) at the rate of 4-5 1 t⁻¹ fresh forage. The effects of FA treatment on proteolysis and amino acid degradation was investigated at several intervals over a 90-d period of ensilage in laboratory silos. Formic acid treatment produced different patterns of pH decline during ensilage of the two forages, suggesting some degree of crop specificity in response to FA treatment. After 7 d of ensilage of lucerne there were increases of 81% in nonprotein nitrogen (NPN), and 104% in free amino acid nitrogen (FAA-N), but with FA-treated lucerne the increases were 39% and 31%, respectively. FA treatment resulted in a reduction in the concentration of most free amino acids in lucerne silage, with the exception of glutamic acid and serine; the branched chain amino acids as well as glycine, tyrosine and proline were significantly (P<0·05) reduced after 3 d of ensilage. By contrast, FA treatment of maize did not significantly ( p <0·05) affect the NPN content nor was there a consistent pattern in the changes in FAA-N. Formic acid treatment of maize did produce a significant reduction ( P <0·05) in the concentration of most individual free amino acids at 90 d of ensilage. Overall, FA treatment had a more predictable effect on proteolysis and amino acid degradation in ensiled lucerne than in ensiled whole-plant maize.     

Growth performance, appetite and plasma ammonia concentrations in heifers fed inoculated lucerne prior to ensilage, then supplemented with sodium bicarbonate

A study was conducted to explore the possibility of a synergistic effect of an inoculum of lactic acid bacteria and sodium bicarbonate in improving the nutritive value of lucerne silage. Twenty Holstein heifers (live weight 183 ± 9·4 kg) were assigned to four dietary treatments consisting of: lucerne uninoculated or inoculated prior to ensilage and then either unsupplemented or supplemented with NaHCO₃ (40 g kg⁻¹ dry matter (DM)). The lucerne silage contained 320 g kg⁻¹ DM and constituted 600 kg⁻¹ diet DM. The animals were fed once daily for 90 d and samples of jugular blood were analysed for plasma ammonia and indices of blood acid-base status. Inoculation of Lucerne reduced ( P <0·01) silage pH but had no other effect on silage composition. In the absence of NaHCO₃, liveweight gain and organic matter intake were improved by inoculating lucerne prior to ensilage; however, in the presence of NaHCO₃, inoculation reduced growth rate but had no major effect on intake. Dietary treatment did not (P>0·05) affect the concentration of plasma ammonia or measures bf blood acid-base status. The results suggest that NaHCO₃ may have nullifled any potential benefit of inoculating lucerne silage to improve its nutritive value for heifers.     

The effect of addition of sugar and inoculation with two commercial inoculants on the fermentation of lucerne silage in laboratory silos

Lucerne (DM 236 g kg^-1, WSC 49 g (kg DM)^-1) was ensiled in test-tube silos with or without either glucose or fructose and with or without one of two commercial inoculants. The WSC content of the forage as ensiled was too low to obtain a well preserved untreated silage. By day 4 the pH values of the silages with added sugar or inoculant were significantly lower (P< 0·001) than the control silage. A satisfactory fermentation was attained only in the silages to which sugar and an inoculant had been added. These silages had a lower pH, more protein-N (P< 0·001), less ammonia-N (P<0·001), a faster increase in counts of lactic acid bacteria, and decrease in counts of coliforms than the other silages. Homo-fermentative lactic acid bacteria dominated the fermentation in the inoculated silages while leuconostocs dominated the early stages of fermentation in the control silages. The results indicate that if there is insufficient sugar in the original crop, then the bacteria in an inoculant will not be able to produce enough lactic acid to lower the pH to an acceptable level. This has important implications for the ensilage of lucerne and other highly buffered low sugar crops.     

Protein supplementation of formic acid- and enzyme-treated silages. 2. Nitrogen and amino acid digestion

Two silages were made from primary growth perennial ryegrass and ensiled after the application of either formic acid or an enzyme mixture of cellulase and hemicellulase. Silage analysis showed both silages to be well preserved with low pH of 3·70 and 3·62 for the formic and enzyme treatments respectively. Formic acid-treated silage had a higher total amino acid concentration than enzyme-treated silage. The silages were offered to growing steers either as the sole diet or supplemented with rapeseed meal at 60 g or 120 g fresh weight kg⁻¹ silage DM offered, in a 6 × 6 Latin square arrangement.
Non-ammonia nitrogen and microbial nitrogen flows at the duodenum (g d⁻¹) were significantly ( P < 0·05) increased by supplementation of enzyme-treated silage compared with formic acid-treated silage (enzyme, 83·6, 58·7; enzyme + 60 g, 101·7, 75·3; enzyme + 120 g, 112·5, 80·7; formic, 91·9, 63·7; formic + 60g, 88·3, 67·9; formic + 120 g, 95·5, 67·1) respectively. Efficiencies of microbial protein synthesis were increased for supplemented enzyme-treated silage diets and values were reduced for supplemented formic acid-treated silage diets compared with the silage only diets (enzyme, 27·9; enzyme + 60 37·7; enzyme + 120 g, 38·6; formic, 33·7; formic + 60g, 31·2; formic + 120 g, 28·8). Total amino acid flow at the duodenum increased with supplementation of both silages; however, microbial amino acid flow increased significantly ( P < 0·05) with supplementation of enzyme-treated silage compared with formic acid-treated silage diets. Significantly greater amounts of cystine, methionine, alanine, valine and aspartic acid entered the small intestines of animals receiving supplemented enzyme silages compared with supplemented formic acid silages.     

Cell wall degrading enzymes for silage. 2. Aerobic stability of enzyme-treated laboratory silages

The effects of two commercial cellulase/hemicellulase enzymes derived from Trichoderma reesei on silage fermentation and aerobic stability were investigated in three laboratory-scale experiments. In Experiment 1, perennial ryegrass ( Lolium perenne ) was treated with enzyme A at the rates of 0. 0·125, 0·250, 0·500 and 0·750 cm³ kg^-1. In Experiment 2, Italian ryegrass ( Lolium multiflorum ) was treated with the same enzyme at the rates of 0, 0·250 and 0·500 cm³ kg^-1 and with 85% formic acid (3·5 cm³ kg^-1). In Experiment 3, perennial ryegrass was ensiled untreated, with enzyme A (0·250 and 0·500 cm³ kg^-1) and with 0·200 and 0·400 cm³ kg^-1 enzyme B which also contained glucose oxidase. All silages were well preserved. Aerobic deterioration was related to numbers of lactate assimilating yeasts. In Experiment 1, all silages were stable over a 4-day period. In Experiment 2, enzyme A treatment delayed the temperature rise compared with the untreated control ( P <0·05), whereas the formic acid-treated silage was stable. In Experiment 3, the temperature rise in the silage treated with the higher level of enzyme B occurred one day later than in the other silages ( P <0·05).     

Influences of enterobacteria on the fermentation and aerobic stability of grass silages

Grass (220 g DM kg⁻¹ was ensiled after adding 10⁶ and 10⁸ enterobacteria (90% Rahnella aquatilis , 9·9% Hafnia alvei and 0·1% Escherichia coli g⁻¹ fresh mutter. The silages were exposed to aerobic conditions alter 125 d of storage. In all treatments H. alvei rapidly superseded the initial high number of Enterobacter agglomerans (naturally present) and R. aquatilis. The maximum number of enterobacteria was detected about I d after initiation of fermentation. After 4 d of fermentation, when concentrations of undissociated lactic and acetic acids ranged from 52 to 36 mM and 41 to 51 mM respectively, no enterobacteria were detectable. Inoculating the crop with enterobacteria restilted in a temporarily retarded rate of production of lactic and acetic acids and a 50% increase in the concentration of ammonia-N. The concentration of endotoxin in the silages was 6–7 μg g⁻¹ fresh matter. There was no change in the level of endotoxin during ensiling. High numbers of enterobacteria at the beginning of the fermentation improved the aerobic stability of the silages. There was a lag in the decrease in concentrations of acids and delays in the increase in pH, respiration rate and numbers of yeast and Bacillus spores, in uninoculated silages the pH increased from 4·1 to 5·0 after 8 d of aerobic storage, whereas in inoculated silages a pH of 5·0 was not reached until after 16 d of storage.