Effects of inoculant treatment on silage fermentation, digestibility and intake by growing cattle

A changeover design experiment involving thirty-six 3-month-old Friesian male calves (mean initial live weight 127 kg) was carried out to evaluate a bacterial inoculant based on a single strain of Lactobacillus plantarum (Ecosyl, ICI) as a silage additive. On 25–31 August 1988, nine silages were harvested using double-chop forage harvesters from the second regrowth of three swards, namely permanent pasture which had received 100 kg N ha^?1 and perennial ryegrass which had received either 100 or 150 kg N ha^?1. Herbages (mean DM and WSC concentrations 144 and 11·2 g kg^?1 respectively) from each sward were treated with either no additive, formic acid (2·4 1 t^?1) or the inoculant (3·3·1 t^?1) and were ensiled in 126 silos of 0·8 t capacity. The only effects of the inoculant on chemical composition of the silages were a decrease in modified acid detergent fibre and an increase in endotoxin and crude and true protein concentrations. Silages were offered ad libitum and supplemented with 1·0 kg of concentrates per head daily for three periods each of 3 weeks in a partially balanced changeover design experiment. Digestibilities of the total diets were determined at the end of the experiment. For the untreated, formic acid-treated and inoculant-treated silages, silage dry matter intakes were respectively 3·58, 3·66 and 3·67 (s.e. 0·044) kg d^?1, estimated metabolizable energy (ME) intakes were 46·1, 46·7 and 47·1 (s.e. 0·44) MJ d^?1, energy digestibilities were 0·727, 0·727 and 0·738 (s.e. 0·0046) and organic matter digestibilities were 0·770, 0·771 and 0·788 (s.e. 0·0042). Rumen degradabilities of the silages were determined using two rumen-fistulated cows. Mean dry matter and nitrogen degradabilities for the control, formic acid-treated and inoculant-treated silages, assuming an outflow rate of 0·05 h^?1, were 10·508, 0·49, 0·491 and 0·702, 0·676 and 0·729. It is concluded that the inoculant significantly increased the digestibility of the silages but did not affect dry matter or ME intake.     

Protein supplementation of formic acid- and enzyme-treated silages. 1. Digestibilities, organic matter and fibre digestion

Two silages were made from perennial ryegrass ensiled without wilting in 2-t capacity silos with the application of either formic acid or an enzyme mixture of cellulases and hemicellulases. Effluent losses were monitored over the ensiling period. Subsequent silage analysis showed that the enzyme-treated silage had higher concentrations of residual water soluble carbohydrate, lactic acid and acetic acid, and lower concentrations of cellulose, ADF and NDF. Effluent production was higher with the enzyme silage (formic acid, 211 1 t^?1; enzyme, 2671 t^?1). The silages were either offered as the sole diet or supplemented with rapeseed meal at two levels (60 or 120 g fresh weight kg^?1 silage DM offered) to growing steers equipped with rumen cannulae and T-piece duodenal cannulae. Apparent whole tract digestibilities for DM, OM, N, ADF and NDF were similar for all diets although nitrogen retention (g d^?1) was increased with supplementation of both silages (formic acid, 21·1; formic acid + 60 g, 23·5; formic acid+ 120 g, 28·5; enzyme, 22·6; enzyme + 60 g, 25·8; enzyme+ 120 g, 31·6). Rumen pH, ammonia and total volatile fatty acids patterns were similar. Supplementation increased the amount of organic matter apparently digested in the rumen (ADOMR) with formic acid-treated silage but not with enzyme-treated silage. Liveweight gains were similar for both unsupplemented silages (0·49 kg d^?1). These increased to 0·55 and 0·65 kg d^?1 for formic + 60 and formic + 120 respectively. Liveweight gains for the corresponding enzyme-treated supplemented diets were 0·81 and 0·91 kg d^?1 respectively. Liveweight gains on supplemented enzyme-treated diets were significantly (P < 0·05) greater than those on formic acid-treated diets.     

Comparison of the fermentation quality and nutritive value of sulphuric and formic acid-treated silages fed to beef cattle

Five experiments were carried out in the years 1980-1983 and 1986 to study the effect of treating grass at ensiling with sulphuric acid (850 g kg^?1) and formic acid (850 g kg^?1) additives alone, and in mixtures with or without formalin on the preservation of grass, in vivo digestibility in sheep, in-silo loss, intake and performance of finishing cattle. Primary growth grass was ensiled in experiments 1 (3–4 June 1980), 2 (12-15 June 1981) and 3 (31 May-2 June 1982), primary regrowth grass in experiment 4 (1-2 August 1983) and secondary regrowth grass in experiment 5 (7-10 October 1986). During the ensiling period within each experiment, approximately 60 t of unwilted, double-chopped, additive-treated or untreated grass was packed into covered concrete-walled 60-t capacity silos. The dry matter (DM) contents of the ensiled grass in experiments 1, 2 and 5 ranged from 155-180 g kg^?1 and were lower than those recorded in experiments 3 and 4 (214 g kg^?1). With the exception of grass ensiled in experiment 2, where water-soluble carbohydrate (WSC) contents were low, at 104 g kg^?1 DM, grass in all other experiments contained relatively high WSC contents ranging from 140-154 g kg^?1 DM. In experiments 1, 3 and 4 all silages were well-preserved. However, in experiment 2 the 450 g kg^?1 sulphuric acid-treated and formic acid-treated silages displayed significantly lower pH, buffering capacity (Bc) and ammonia nitrogen contents than the untreated silage. In experiment 5, the sulphuric acid-treated and formic acid-treated silages displayed significantly lower pH, Bc, ammonia nitrogen, butyrate and volatile fatty acid (VFA) contents than the untreated silage. Each of the silages was offered daily with various levels of a supplementary concentrate for approximately 70-d periods to twelve animals of mixed breed in experiments 1, 3, 4 and 5 and to fifteen animals in experiment 2. All animals weighed between 380-470 kg at the start of the experiments. In experiments 1, 2 and 3 there were no significant differences between silages for any of the intake or animal performance parameters. In experiment 4, cattle fed the formic acid-treated silage displayed significantly higher silage DM intakes and daily liveweight gains than those fed the sulphuric acid-treated and untreated silages; in experiment 5, cattle fed the formic acid-treated silage displayed significantly higher silage DM intakes than those fed the untreated silage. It was concluded that formic acid was a more effective silage additive than sulphuric acid. Increasing the level of supplementation significantly decreased silage DM intakes in cattle in experiments 3 and 4, and significantly increased daily liveweight gains and daily carcass in cattle in experiments 1, 3 and 4.     

A further study on the evaluation through lactating cattle of a bacterial inoculant as an additive for grass silage

An experiment is described in which three silages were prepared from herbage treated with either a bacterial inoculant (Ecosyl, Imperial Chemical Industries plc) at 2-71 t^?1, formic acid (850 g kg^?1, Add-F, BP Chemicals International Ltd.) at 2-21 t^?1, or no additive (control). The herbage (second regrowth from perennial ryegrass swards), was ensiled unwilted, and had mean dry matter (DM) and water-soluble carbohydrate concentrations at ensiling of 186 and 34-1 g kg^?1 respectively. The resulting silages were all well preserved and had only minor chemical differences. Thirty lactating British Friesian cows were subjected to a 21 d standardization period and were then offered the three silages for 21 d in a randomized-block design experiment. The animals were stalled individually, offered the silages ad libitum and in addition received 5 kg d^?1 of a supplement containing 198 g crude protein kg DM^?1. The mean silage DM intake, milk yields and milk fat concentrations during the final 7 d on treatment were 8-44, 8-62 and 887 kg d^?1; 238, 230 and 25-1 kg d^?1; and 368, 400 and 366 g kg^?1 for the control, formic acid- and inoculant-treated silages respectively. Following the feeding trial, six cows per treatment were subdivided to provide three animals which were offered silage alone, and three offered silage plus 5 kg d-’supplement. Rumen samples taken after 21 d on these treatments indicated no effect of the inoculant on ruman volatile fatty acid proportions, whereas the use of formic acid resulted in increases in both acetate and butyrate concentrations. The results from this study support that of the earlier work that this particular inoculant, when used at ensiling, can considerably improve animal performance over that achieved with both untreated and formic acid-treated silages.     

An evaluation of an inoculant/enzyme preparation as an additive for grass silage for dairy cattle

Herbage from the first regrowth of perennial ryegrass-based swards was directly ensiled after treatment with a bacterial inoculant/enzyme preparation (SIL-ALL, Alltech UK) at 3·0 1 t^?1, formic acid (850 g kg^?1) at 2·59 1 t^?1 or no additive (Control). The mean dry matter (DM) and water-soluble carbohydrate concentrations of the grass were 185 and 24·0 g kg^?1 (fresh basis) respectively. Lactic acid concentrations after ensiling increased at a lower rate in formic acid-treated herbage than with the other treatments. All silages were well preserved and formic acid-treated silage had a lower ultimate concentration of lactic acid and higher concentration of water-soluble carbohydrate. Effluent output was increased on a proportional basis by ?0·06 with formic treatment, whereas the inoculant reduced effluent output by 0·05 in comparison with the mean effluent production of the control silage. The in vivo digestibilities of the silages were determined using sheep. The digestibilities of DM, organic matter and energy were significantly higher with inoculant-treated silage than with formic acid treatment, whereas values for the control silage were intermediate. The three silages were offered ad libitum to forty dairy cows with individual recording of daily intakes for a 10-week period in a randomized block experiment with four treatments. Sixteen animals were offered the control silage with half of these offered 3 kg concentrates per day (C3) and the other half offered 7 kg concentrates per day (C7). Twelve animals were allocated to each of the additive-treated silages, with concentrates offered at 5 kg d^?1. Treatment effects on animal performance were measured in weeks 7–10. To compare animal performance for the treated silages with the control, an estimate of performance at 5 kg concentrates per day was obtained by regression using values obtained at 3 and 7 kg concentrates. In comparison with estimated silage intake for the control silage with 5 kg d^?1 concentrates, inoculant and formic acid treatment of the silages increased dry matter intake by 0·04 (P > 0·05) and 0·13 (P > 0·01) respectively. In comparison with estimated milk production and yield of fat plus protein for the control treatment with 5 kg d^?1 concentrates, neither inoculant treatment nor formic acid treatment produced any significant differences.     

An evaluation through lactating cattle of a bacterial inoculant as an additive for grass silage

Three silages were prepared from herbage treated with either an inoculant (Ecosyl, Imperial Chemical Industries plc) at 3.21 t^?1, formic acid (850 g kg^?1, Add F BP Chemicals International Ltd) at 2·3 1 t^?1, or no additive (control). The herbage used was the first regrowth from perennial ryegrass swards. It was ensiled unwilted, and had mean dry matter and water soluble carbohydrate concentrations at ensiling of 154 and 24·1 g kg^?1 respectively. Time course studies showed only minor effects of additive treatment on fermentation patterns within the silo and all three silages had good fermentations. Over an 88 d feeding period, commencing on day 7 of lactation, forty-eight British Friesian cows were used to evaluate the silages in a three-treatment, randomized-block design experiment. The animals were stalled individually, offered the silages ad libitum, and in addition received 5 kg d^?1 of a supplement containing 196 g kg^?1 crude protein. On the basis of the data recorded during the final 28 d on treatment the animals receiving the inoculant-treated silage consumed 12 and 10% more silage dry matter and produced 2·1 and 2·3 kg d^?1 more milk than those given the control and formic acid-treated silages respectively. Over the total experimental period the milk yields were 1957, 1894 and 2094 (±41·3) kg for animals receiving the control, formic acid- and inoculant-treated silages respectively. Animals offered the formic acid treated silage produced milk of significantly higher fat concentration than those given the other two silages. Total ration digestibility studies, conducted with three cows per treatment, indicated no significant differences in digestibility coefficients, nitrogen utilization or metabolizable energy concentrations of the three treatment diets. It is concluded that the higher milk yield recorded with the inoculant-treated silage, and the higher milk fat concentration with the formic acid-treated silage, over that obtained with the control silage, were due to the increases in ME intake of 5 and 16 MJ d^?1 for the formic acid and inoculant-treated silages respectively.     

The effect of wilting and silage additives on the fermentation of autumn made grass silage ensiled in bunkers on commercial farms in South Wales 1983-85

Silage making practices in respect of 130 samples of autumn made grass silages ensiled in bunkers on commercial farms in South Wales during 1983-1985 were analysed to discern the effect of wilting and/or silage additives on fermentation. Silages were primarily made during late September and early October in fine weather from perennial ryegrass pasture which had not been grazed for 6 weeks. On average 13.9 ha of pasture was cut for silage. Analysis of 120 samples of grass showed it contained 176 g kg^?1 dry matter (DM) with (g kg^?1 DM) 215 protein, 240 modified acid detergent fibre (MADF), 78 water-soluble carbohydrate (WSC) and 95 ash. Most farmers attempted to pre-wilt grass for 1 day prior to ensilage and one quarter of them made unwilted silage. Silage making was usually completed within 6 days of starting to cut and was generally made with a precision-chop machine. Silage additives applied were (kg t^?1) formic acid (4·7), formic acid 4-formalin (5·5), sulphuric acid-+ formalin (5·0) sugars (14) and inoculants (0·65). Formic acid significantly reduced pH, and formic acid with or without formalin significantly reduced ammonia nitrogen (N) content of silages compared with other treatments. Protein contents of acid/formalin treated silages were significantly higher and MADF of acid with or without formalin treated silages were significantly lower than other treatments. Pre-wilting grass prior to ensilage did not significantly increase subsequent silage DM content and significantly increased the pH of non-additive treated silages. Unwilted silages treated with formic acid with or without formalin had a significantly lower ammonia-N content and higher residual WSC than other treatments. It is suggested that only formic acid application either alone or in conjunction with formalin to unwilted silage was successful in producing well preserved silages and that a grass WSC content of 17 g kg^?1 would be necessary to achieve this.     

Silage and milk production: a comparison between additives for silage of high digestibility

Three grass silages made in early June from S23 perennial ryegrass were compared in a 16-week feeding experiment with twelve Ayrshire cows. The silages were made from uniform herbage which received either formic acid (‘Add-F’) at the rate of 201 t^?1, or a formalin-sulphuric acid mixture (‘Syiade’) at rates of 2.0 and 4.4 1 t^?1. The silages were offered ad libitum either alone or supplemented with a cube containing 38% CP in the DM at the rate of 1.4 kg per 10 kg milk. The daily intakes of silage DM were not significantly different on the three silage treatments, and averaged 10.7, 11.0 and 11.0 kg per cow on the formic acid and the 2.0 and 44 1 t^?1 formalin-acid treatments respectively. The mean daily yields of milk were 15.1, 13.3 and 13.7 kg per cow in the unsupplemented treatments, and 18.2, 18.1 and 18.0 kg per cow in the supplemented treatments on the formic acid and the 2.0 and 44 1 t^?1 formalin-acid treatments respectively. On the basis of total animal production expressed in terms of metabolizable energy requirements, it was concluded that the differences between the three silages were small.     

The effect of dry feed additives on the nutritive value of silage

Silages were prepared in late September from a mixed crop of perennial ryegrass and white clover with low dry matter and high nitrogen content. Six different treatments were used during ensiling; addition of either molassed sugar beet pulp or rolled barley, at 50 kg and 25 kg (t fresh grass)^?1, formic acid at 51 t^?1 and no additive (control). All silages were well fermented with low levels of ammonia and pH. The addition of rolled barley or sugar beet pulp increased the dry matter content of the silages incrementally and appeared to assist the retention of nitrogen in the silage. Dry matter intakes of silages with 50 kg of barley or sugar beet pulp tonne^?1 were similar to the control silage when fed to wether sheep but at 25 kg t^?1, dry matter intake increased by 0·15 with barley and 0·04 with sugar beet pulp compared to the control. The digestibility of dry matter (DM) and organic matter (OM) were significantly higher than the control for silages treated with formic acid or high levels of barley and sugar beet pulp whereas neutral-detergent fibre (NDF) digestibility did not appear to be significantly affected. All treated silages had a significantly higher metabolizable energy (ME) content than the control, and additions of barley or sugar beet increased the ME content. The ME intakes of all treated silages were also significantly greater than those of the control, and the formic acid-treated and low barley silages were the highest. This appeared to be associated with significantly higher energy digestibility and DM intake. Addition of rolled barley during ensilage resulted in greater nitrogen intake, availability and retention compared to additions of sugar beet pulp. The higher retention with barley silages was associated with a significantly lower proportional loss of absorbed nitrogen in urine, which indicated a more efficient utilization of nitrogen. These differences require further study to determine the mechanisms involved in the interactions between the energy source and herbage protein, both during fermentation and in the rumen.     

Possibilities of increasing the residual water‐soluble carbohydrate concentration and aerobic stability of low dry‐matter perennial ryegrass silage through additive and cultivar use

Increasing the residual water‐soluble carbohydrate (WSC) concentration in silage may improve the nutritional value but impair aerobic stability. Our aim was to determine whether the residual WSC concentration and aerobic stability of low dry‐matter (<135 g kg^?1) perennial ryegrass silage could be manipulated through the judicious use of additive and cultivar. Seven additive treatments, including three innovative treatments, were compared across four consecutive harvests of the cultivars AberDart (bred to accumulate high concentrations of herbage WSC) and Fennema (control). The standard of fermentation of silage ensiled without additive (untreated) ranged from very bad to excellent. Application of ammonium tetraformate, at 3 and 6 L t^?1, or homofermentative lactic acid bacteria (LAB) alone had an inconsistent effect on the fermentation and aerobic stability, and negligible effect on residual WSC concentration. A mixture of Lactobacillus buchneri and homofermentative LAB was not an effective silage additive, producing generally poorly fermented silage. An antimicrobial mixture of sodium benzoate, sodium propionate, sodium nitrite and hexamethylenetetramine, applied at 2·5 and 5 L t^?1, frequently improved the standard of fermentation, but the effects were subject to the application rate. The high application rate was the most effective additive evaluated at improving the fermentation and increasing residual WSC concentration and consistently produced silage of excellent standard of fermentation. However, the antimicrobial mixture was not effective at protecting against aerobic instability. The effects of additive treatment were largely inconsistent across cultivars. Overall, AberDart had a negligible effect on the silage fermentation, residual WSC concentration and aerobic stability compared with Fennema.     

The effect of sugar beet pulp-based silage additives on effluent production, fermentation, in-silo losses, silage intake and animal performance

First-harvest direct-cut, double-chopped grass (190 and 164g DMkg^?1 in Experiments 1 and 2 resptectively) was ensiled without an additive or, in Experiment 1, with 30 kg t^?1 grass of an absorbent additive based on sugar beet pulp (Sweet ‘n’ Dry) or with 3·441 t^?1 grass of formic acid and, in Experiment 2, with 30, 50 and 70 kg t^?1 grass of Sweet ‘n’ Dry or with 50kg t^?1 grass of unmolassed sugar beet pulp. The preservation and nutritive value of the silage, in-silo losses (including silage effluent production), silage intake and animal performance of adult and growing cattle were examined. In Experiment 1 all three silages were well preserved, although the formic acid-treated silage displayed significantly lower pH, ammonia nitrogen (NH₃N) [g kg^?1 total nitrogen (TN)] and volatile fatty acids (VFAs) than the other two silages. In Experiment 2 absorbent-treated silages displayed significantly lower pH, buffer capacity (Bc), NH₃N (gkg^?1 TN), CP, modified acid detergent fibre (MADF) and VFAs than untreated silage. Treatment of grass with the absorbent additives at ensiling resulted in reduced effluent production. In Experiment 1 each kilogram of Sweet ‘n’ Dry retained approximately 11 effluent, and in Experiment 2 silages made with Sweet ‘n’ Dry applied at 70kgt^?1 and sugar beet pulp applied at 50 kg t^?1 produced similar volumes of effluent and each kilogram of absorbent retained 1·0 and 1·31 of effluent respectively. In Experiment 1 sixty beef cattle [mean initial live weight (LW) 460 kg] were grouped according to LW and allocated to treatment at random. For untreated silage (unsupplemented or with 1 or 2 kg supplement head^?1 day^?1), absorbent-treated silage (unsupplemented or with 1 or 2 kg supplement head^?1 day^?1) and formic acid-treated silage (1 kg supplement head^?1 day^?1) the daily silage DM intakes were 6·12, 6·21, 6·40, 7·65, 7·45, 7·11 and 7·85 (s.e. 0·280) kg respectively, the daily liveweight gains were 0·22, 0·56, 0·81, 0·59, 0·74, 0·81 and 0·75 (s.e. 0·071) kg respectively and daily carcass gains were 0·31, 0·47, 0·67, 0·47, 0·61, 0·70 and 0·57 (s.e. 0·043) kg respectively throughout a 75-day feeding period. In Experiment 2, fifty-six growing cattle (mean initial weight 312 kg) were grouped according to LW and allocated to treatment at random. For untreated silage (unsupplemented or with 1·5 kg Sweet ‘n’ Dry or 1·5 kg commercial concentrates head^?1 day^?1), silage treated with Sweet ‘n’ Dry at 30, 50 and 70 kg t^?1 grass and silage treated with 50kg sugar beet pulp t^?1 grass the daily silage DM intakes were 5·46, 5·28, 5·33, 6·21, 6·27, 6·60 and 6·62 (s.e. 0·154) kg respectively and daily liveweight gains were 0·39, 0·75, 0·81, 0·63, 0·76, 0·94 and 1·75 (s.e. 0·052) kg respectively throughout a 122-day feeding period. In this experiment 360g kg^?1 more absorbent was required when it was included at ensiling rather than offered as a supplement to untreated silage to achieve the same individual animal performance.     

Effects of inoculant treatment on ryegrass silage fermentation, digestibility, rumen fementation, intake and performance of lactating dairy cattle

A randomized block experiment involving thirty-six lactating dairy cattle was carried out to evaluate a bacterial inoculant (Grazyme Grobac, Agritech), containing bacteria, enzymes and a rumen enhancer, as a silage additive. Herbage from the primary regrowth of predominantly perennial ryegrass swards was ensiled unwilted and precision-chopped after a 51-d growth interval on 4 and 5 August. Alternate loads of herbage were ensiled either untreated (C) or treated with formic acid at a rate of 2.65 1 (t herbage)^?1 (F) or the inoculant at a rate of 0.64 kg (t grass)^?1 (I). The treatments were harvested using the same harvester in the rotation of I, F and C treatments. Mean dry-matter (DM), water-soluble carbohydrate and nitrate nitrogen (N) concentrations and buffering capacity of the C herbages at ensiling were 198 g kg^?1, 18 2 g kg^?1, 290 mg (1 juice)^?1 and 379 mequiv. (kg DM)^?1 respectively. For silages C, F and I pH values were 3.7, 3.8 and 3.8 and ammonia N concentrations 61, 43 and 58 g (kg total N)^?1 respectively. Inoculant treatment did not alter aerobic stability of the silages, whereas formic acid treatment increased it. The silages were offered ad libitum and supplemented with 5 kg of concentrates per head daily. For treatments C, F and I silage DM intakes were 10.8, 11.2 and 10.8 (s.e. 0–33) kg d^?1, milk yields 21.3, 20.9 and 20.7 (s.e. 0.52) kg d^?1, fat concentrations 38.3, 40.3 and 37.2 (s.e. 0.83) g kg^?1 and protein concentrations 30.8, 32.6 and 32.6 (s.e. 0.49) g kg^?1 respectively. Inoculant treatment did not alter (P0.05) the digestibility coefficients of the total diets, whereas formic acid treatment decreased DM (P0.05), organic matter (P0.05), neutral detergent fibre (P0.01) and hemicellulose (P0.01) digestibilities. Formic acid treatment altered rumen fermentation patterns, whereas inoculant treatment had no effect. It is concluded that, relative to a well-preserved untreated silage, additive treatment did not alter DM intake, milk yield or fat plus protein yield. However, both additive treatments increased milk protein concentrations and formic acid treatment increased milk fat concentration relative to the well-preserved, untreated silage.     

The effects of incorporating sugar-beet pulp with herbage at ensiling on silage fermentation, effluent output and in-silo losses

Three studies were undertaken with the aim of examining in-silo losses associated with ensiling mixtures of beet pulp and herbage. In Experiment 1, first-regrowth perennial ryegrass was ensiled untreated or mixed with either 40 or 120 kg unmolassed beet pulp t^?1 fresh grass prior to ensiling. In each of Experiments 2 and 3, second-regrowth ryegrass was ensiled untreated or mixed with either 40, 80 or 120 kg unmolassed beet pulp t^?1 fresh grass prior to ensiling. Dry-matter concentrations of herbage ensiled in Experiments 1, 2 and 3 were 141, 157 and 139 g kg^?1 respectively. Time-course studies indicated a more rapid fermentation with the untreated silages. Ensiling beet pulp with herbage resulted in significant improvements in silage fermentation, reflected in reductions in silage pH and ammonia nitrogen concentrations, with these effects being pronounced at beet pulp inclusion in excess of 80kg t^?1. Beet pulp inclusion increased the dry-matter concentrations of the resulting silages while reducing crude protein, modified acid detergent fibre and gross energy concentrations. In Experiment 1 beet pulp retained 1·62 and 1·641 effluent kg^?1 at the 40 and 120kg t^?1 application rates respectively. In Experiments 2 and 3, effluent retentions were 1·40, 1·29 and 0·93 1 kg^?1 and 2·87, 2·19 and 1·781 kg^?1 at the 40, 80 and 120kg t^?1 beet pulp inclusion rates respectively. In each of Experiments 1 and 3, in-silo losses were reduced with increasing level of beet pulp inclusion, while in Experiment 2 in-silo losses were relatively unaffected by treatment. Nutrient losses in effluent were reduced by the inclusion of beet pulp in all three experiments, while nutrient losses in surface waste and invisible nutrient losses tended to increase with higher levels of beet pulp inclusion. It is concluded that the inclusion of beet pulp with herbage at ensiling can result in an improved silage fermentation and a reduction in in-silo losses, while at the same time retaining considerable quantities of effluent within the silo. However, with herbage dry-matter concentrations below 160gkg^?1, beet pulp inclusion in excess of 120 kg t^?1 herbage would be required to eliminate effluent production totally.     

The effect of additives on the ensilage of forage of differing perennial ryegrass and white clover content

Pure perennial ryegrass or perennial ryegrass/white clover mixtures (70:30 and 40:60 on a fresh-matter basis) were ensiled in laboratory silos either untreated or alter treatment with freshly cultured Lactobacillus (Lb.) plantarun or freshly cultured Lb. plantarum plus Lactococcus (Lc.) lactis. freeze-dried Lb. plantarum or freeze-dried Lb. Plantarum plus sodium formate, sodium formate or formic acid. The effect of these additives on silage fermentation characteristics and quality of the resultant silages was examined. There were significant interactions between treatments and herbages for all silage quality parameters measured, except for acetic acid concentration. The influence of additives on the final pH of all silages was small but statistically significant. Lactic acid concentration was not directly related to herbage mixture, overall mean values ranging from 118 to 120 ± 1.5 g kg^?1 dry matter (DM), but wider variation was seen between treatments for individual herbage mixtures. Acetic acid concentrations were significantly (P<0·001) affected by herbage mixture ensiled, increasing linearly as clover content increased from zero to 60%. Untreated control and formic acid-treated silages contained significantly (p<0·001) higher acetic acid concentrations than those treated with other additives. Silage ammonia N concentrations were significantly (p<0 001) influenced by herbage mixture. Lowest ammonia N concentrations (< 50 g kg^?1 DM) were observed in silages that had been treated with formic acid, freshly cultured Lb. plantarum or Lb. plantarum plus Lc. lactis. The fraction 1 leaf protein (FILP) contents of silages were significantly (P <0·001) affected by both treatment and herbage mixture, with consistently and significantly higher values found in freshly cultured inoculant-treated silages. A poor correlation (r²= 0·12) existed between ammonia N and FILP in all silages. The inclusion of up to 60% white clover in the ensiled herbage did not adversely affect final silage quality. However, additive treatment markedly influenced the residual FILP content of silages, those treated with freshly cultured inoculants having the highest values.     

Enzymes as silage additives 2. The effect of grass dry matter content on silage quality and performance in sheep

Eight grass silages were made from two contrasting varieties of perennial ryegrass, four silages each from a late-cut early-maturing (high dry matter, HDM) variety and from an early-cut, late-maturing (low dry matter, LDM) variety. The grass was ensiled without additive (untreated), or with formic acid, or with one of two enzyme mixtures of hemicellulases and cellulases (enzyme 1 and enzyme 2) for a period of 130 d.
Formic acid-treated silage had lower levels of lactic acid at both levels of dry matter than the other silages. Enzyme treatment of grass prior to ensilage resulted in reduced levels of cellulose, acid-detergent fibre and neutral-detergent fibre in LDM silages and lower acid-detergent fibre and neutral-detergent fibre in the HDM silages compared with the corresponding untreated and formic acid-treated silages. Voluntary intakes (g DM d⁻¹) of untreated and enzyme-treated silages were significantly ( P <0·01) lower at both digestibilities compared with formic acid-treated silages (LDM: untreated, 982; formic, 1069; enzyme 1, 868; enzyme 2, 937; HDM: untreated, 931; formic, 1027; enzyme 1, 943; enzyme 2, 914). The organic matter, carbohydrate and nitrogen digestibility coefficients of LDM silages were significantly ( P <0·001) higher than those of HDM silages. There were no significant differences in any component digestibility related to silage additive.
Comparison of digestibility coefficients for constituents of the LDM silages fed to sheep or steers showed no differences between species.     

Increased concentration of water-soluble carbohydrate in perennial ryegrass (Lolium perenne L.). Evaluation in dairy cows in early lactation

Twelve multiparous Holstein–Friesian dairy cows in early lactation were used to investigate the potential of using perennial ryegrass (Lolium perenne) with a high concentration of water‐soluble carbohydrates (WSC) to increase the efficiency of milk production. Ad libitum access to one of two varieties of zero‐grazed herbage was given continuously for 3 weeks: treatment High Sugar (HS), an experimental perennial ryegrass variety (Ba11353) bred to contain a high concentration of WSC, harvested in the afternoon; or Control, a standard variety of perennial ryegrass (cv. AberElan), harvested in the morning. All dairy cows also received 4 kg d^?1 of a standard dairy concentrate. Dairy cows given the HS diet treatment consumed 2·8 kg dry matter (DM) d^?1 more than Control dairy cows (P < 0·01), and the DM digestibility of the diet on the HS treatment was significantly greater than that of the diet on the Control treatment (0·75 vs. 0·72; s.e.d. 0·010; P < 0·05). Excretion of urinary purine derivatives (PD) tended (P < 0·1) to be higher from dairy cows on the HS treatment, implying increased microbial protein flow to the duodenum, although there was no significant difference in the apparent efficiency of rumen fermentation of either dietary nitrogen (N) or DM expressed as a ratio to urinary PD. Milk yields and milk composition were not significantly affected by dietary treatment, although true protein yields of milk were higher (P < 0·05) from dairy cows given the HS treatment. The proportion of dietary N excreted in urine was significantly lower from HS cows, although the values were low for both treatments (0·20 g g^?1 vs. 0·27 g g^?1; s.e.d. 0·020; P < 0·05). It is concluded that increased DM intakes by dairy cows given the HS treatment led to increased milk protein outputs. With a proportional decrease in urinary N excretion, the use of perennial ryegrass with a high WSC concentration, in the context of the harvesting regime used in this study, may help to reduce N pollution from dairy systems into which it is incorporated.     

Characteristics of baled silage made from first and second harvests of wilted and severely wilted forages

First and second harvests of lucerne (Medicago sativa L.), perennial ryegrass (Lolium perenne L.) and a lucerne–perennial ryegrass mixture [80 or 144 g kg^?1 dry matter (DM) of ryegrass] at the first and second harvests were cut and conditioned, wilted to 500 or 700 g DM kg^?1 then baled and stretch‐wrapped for silage on the same dates. Lucerne bales were denser (411 kg m^?3) than bales of perennial ryegrass (331 kg m^?3) (P < 0·05). After an 8‐month storage period, silage made from high DM‐content forage had a higher concentration of neutral‐detergent fibre (NDF) and was less digestible than that made from low DM‐content forage. Daily DM intakes by beef steers, when the silages of the second harvest were fed ad libitum, were 31·2, 31·2 and 22·3 g kg^?1 live weight for lucerne, lucerne–perennial ryegrass mixture and perennial ryegrass silages, respectively (P < 0·01), when the herbage had been wilted to 500 g kg^?1. In vivo digestibility of NDF in the lucerne–perennial ryegrass mixture silage (0·587) was significantly lower than that of perennial ryegrass silage (0·763) but higher than lucerne silage (0·518). Higher intakes of baled lucerne silage tended to offset its lower digestibility values. Lucerne–perennial ryegrass mixture silage had a higher DM and NDF digestibility than lucerne silage, indicating perhaps the presence of associative effects.     

The effects of treating low dry-matter, low digestibility grass with a bacterial inoculant on the intake and performance of beef cattle, and studies on its mode of action

This experiment evaluated a bacterial inoculant based on a single strain of Lactobacillus plantarum as a silage additive. Three silages were harvested on 8 September 1989 from the second regrowth of a perennial ryegrass sward, which had received 167 kg N, 28 kg P₂O₅ and 45 kg K₂O ha^?1. Mean dry matter (DM) and water soluble carbohydrate concentrations of the herbages at ensiling were 148 g kg^?1 and 78 g.(kg DM)^?1 respectively. Herbages were treated with either no additive (C), formic acid (3·0 1 t^?1) (F) or the inoculant (3·0 1 t^?1) (I) and were ensiled in three 80-t capacity silos. For silages C, F and I respectively, pH values were 4·70, 3·77 and 4·47, ammonia-N concentrations were 192, 111 and 182 g (kg total N)^?1 and butyrate concentrations were 6·8, 1·8 and 7·1 g (kg DM)^?1. The silages were offered ad libitum and supplemented with 2·0 kg concentrates per head daily to thirty-six heifers (mean initial live weight 442 kg). For silages C, F and I, silage DM intakes were 12·7, 14·4 and 14·1 (s.e. 0·42) g (kg live weight)^?1, metabolizable energy intakes were 155, 166 and 172 (s.e. 5·1) kJ (kg live weight)^?1, and estimated carcass gains were 456, 519 and 518 (s.e. 28·1) g d^?1 respectively. A further 18 similar cattle were used in studies on the digestibility of the silages, and rumen degradation of each was estimated with three mature cattle. Inoculant treatment significantly increased crude fibre (P <0·01), neutral detergent fibre (P <0·01), modified acid detergent fibre (P <0·01), hemicellulose (P <0·05) and N digestibilities (P <0·05) and tended to increase N retention from the total diet. It is concluded that although treatment of herbage that was difficult to ensile with the inoculant did not improve silage fermentation, it significantly increased digestibility, especially of the fibre fractions, and silage DM intake and tended to increase animal performance to levels similar to those achieved with a well preserved formic acid-treated silage. Increases in silage DM and metabolizable energy intakes are likely to have been attributable to the effects of the inoculant on digestibility, especially of the fibre fractions.     

Effect of formic acid and a bacterial inoculant on the amino acid composition of grass silage and on animal performance

An Italian ryegrass and hybrid ryegrass sward was harvested on 11 May 1994. The mean dry‐matter (DM) content of the herbage was 197 g kg^–1 fresh matter (FM), and mean nitrogen and water‐soluble carbohydrate contents were 20 and 272 g kg^–1 DM respectively. Approximately 72% of total nitrogen (TN) was in the form of protein‐nitrogen. The herbage was treated with either no additive, formic acid (3·3 l t^–1) (Add‐F, BP) or inoculant (2·3 l t^–1) (Live‐system, Genus) and ensiled in 100 t silos. Changes in effluent composition with time showed that silage fermentation and protein breakdown were delayed by treatment with formic acid. Formic acid and inoculant treatments also inhibited amino acid catabolism during ensilage. All silages were well fermented at opening with pH values < 4·0 and ammonia‐N concentrations of ≤ 50 g kg^–1 TN after 120 d ensilage. Treatment had an effect on protein breakdown as measured by free amino acid concentration, with values of 21·5, 18·2 and 13·2 mol kg^–1 N at opening (191 d) for untreated, formic acid‐treated and inoculated silages respectively. Amino acid catabolism occurred to the greatest extent in untreated silages with significant decreases in glutamic acid, lysine and arginine, and increases in gamma amino butyric acid and ornithine. The silages were offered ad libitum without concentrate supplementation to thirty‐six Charolais beef steers for a period of 69 d (mean live weight 401 kg). Silage dry‐matter intakes and liveweight gains were significantly (P < 0·05) higher on the treated silages. Silage dry‐matter intakes were 7·42, 8·41 and 8·23 kg d^–1 (s.e.d. 0·27) with liveweight gains of 0·66, 0·94 and 0·89 kg d^–1 (s.e.d. 0·058) for untreated, formic acid‐treated and inoculated silage‐fed cattle respectively. In conclusion, additives increased the intake of silage and liveweight gain by the beef steers, and it is suggested that this may be caused in part by the amino acid balance in these silages.     

Effects of treating low dry-matter grass with a bacterial inoculant on the intake and performance of beef cattle and studies on its mode of action

A randomized block design experiment involving thirty beef cattle (mean initial live weight 462 kg) was carried out to evaluate a bacterial inoculant based on a single strain of Lactobacillus plantarum as a silage additive and to provide further information in relation to its mode of action. Three herbages were harvested on 10 August 1989 using three double-chop forage harvesters from the first regrowth of a perennial ryegrass sward which had received 170 kg N, 25 kg P₂O₅, and 42 kg K₂O ha^?1. They received either no additive (silage C), formic acid at 2·91 (t grass)^?1(silage F) or the inoculant at 3·21 (t grass)^?1 (silage I). Mean dry-matter (DM), water-soluble carbohydrate and crude protein concentrations in the untreated herbages were 158g kg^?1, 88 g (kg DM)^? and 183g (kg DM)^?1 respectively. For silages C, F and I respectively, pH values were 4·01, 3·57 and 3·62; ammonia N concentrations 117, 55 and 77 g (kg total N)^?1; and butyrate concentrations 2·18, 0·50 and l·24g (kg DM)^?1. The silages were offered ad libitum and supplemented with 2·5 kg concentrates per head daily for 77 days. For treatments C, F and I, silage DM intakes were 6·59, 7·25 and 6·80 (s.e. 0·074)kg d^?1; metabolizable energy (ME) intakes 86,99 and 94 (s.e. 0·8) MJ d^?1; liveweight gains 0·90, 0·97 and 1·02(s.e.0·066) kg d^?1; carcass gains 541,656 and 680 (s.e. 34·0) g d^?1. Inoculant treatment increased DM (P < 0·01), organic matter (P < 0·01), crude fibre (P < 0·05), neutral detergent fibre (NDF) (P < 0·05) and energy (P < 0·05) digestibilities, the digestible organic matter concentration (P < 0·01) and the ME concentration (P < 0·05) of the total diets. Additive treatment altered rumen fermentation patterns but had little effect on the rumen degradability of silage DM, modified acid detergent (MAD) fibre, NDF or hemicellulose. It is concluded that treatment with the inoculant improved silage fermentation and increased digestibility, had little effect on silage DM intake but significantly increased carcass gain to a level similar to that sustained by a well-preserved formic acid-treated silage