Silage Dry Matter Research Articles

Establishment of Switchgrass and Big Bluestem in Corn with Atrazine

AbstractSwitchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) provide abundant forage for livestock and wildlife during hot summer months when cool‐season grass species may decline in production. Little biomass production for grazing may result during warm‐season grass establishment because of weed competition. Chemical methods of weed control are now limited, because application of atrazine [6‐chloro‐N‐ethyI‐N'‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] to switchgrass and big bluestem is no longer allowed according to the label. Using corn (Zea mays L.) as a companion crop could provide potential for high biomass production during warm‐season grass establishment, and allow the use of atrazine for weed control. This study investigated the ability of switchgrass and big bluestem to establish in a corn companion crop. The effects of corn hybrid (short‐ vs. long‐season), population density, row spacing, and harvest date on switchgrass and big bluestem stands and on corn production were quantified. Establishment of switchgrass and big bluestem in corn was successful. Switchgrass mean stands were 26.3 plants m−2 in 1995 and 46.4 plants m−2 in 1996. Big bluestem stands were similar to switchgrass in 1995 (31.7 plants m−2), but were much lower in 1996 (5.2 plants m−2). Long‐season corn hybrids and higherdensity corn populations increased corn silage and grain yield without reducing warm‐season grass stands. Within a season, no difference existed between corn grain yields when grown with either switchgrass (6.7 Mg ha−1 in 1995, 5.3 Mg ha−1 in 1996) or big bluestem (6.9 Mg ha−1 in 1995, 5.7 Mg ha−1 in 1996). Silage dry matter yield was not different between corn grown with switchgrass (12.6 Mg ha−1 in 1995, 16.1 Mg ha−1 in 1996) and corn grown with big bluestem (13.1 ha−1 in 1995, and 16.6 Mg ha−1 in 1996) for a given year. Switchgrass and big bluestem grown in corn with atrazine reduced land production losses during the establishment year, yet allowed adequate establishment of these grasses for future forage production.

Starch Supplementation of Grass Harvested at Two Stages of Maturity Prior to Ensiling: Intake, Digestion, and Degradability by Dairy Cows

The effects of the maturity of grass prior to ensiling and the supplementation of starch to grass silage on apparent digestibility, degradability, rumen content, and feed intake by dairy cows were investigated using a Latin square design. Treatments were silages from early or late cut grass with or without 4kg of supplemental flaked corn starch. The silage from early cut grass contained more N and sugars than did the silage from late cut grass but was lower in neutral detergent fiber (NDF). Degradation characteristics were not different between the two silages. Apparent digestibilities of dry matter (DM), organic matter (OM), and N in the silage from late cut grass were lower than those in the silage from early cut grass, but NDF digestibility was not affected. Starch supplementation increased the lag phase for DM and OM in both silages, but the rate of degradation was decreased for NDF. Starch supplementation did not influence digestibilities of DM and OM in silage from early cut grass but decreased the digestibilities of DM and OM in silage from late cut grass. Crude protein and NDF digestibilities were decreased for silages from early and late cut grass. Starch supplementation increased NDF in the rumen of cows fed the silage from early cut grass, but NDF was not affected by starch supplementation for cows fed the silage from late cut grass. Rumen-degradable starch negatively influences degradability and apparent OM digestibility; the extent of the decrease is related to the maturity of the NDF.

Effects of bacterial inoculation of unwilted and wilted grass silages. 1. Rumen microbial activity, silage nutrient degradability and digestibility

A set of four silages, comprising unwilted and wilted silages, both with and without bacterial inoculation, was prepared from perennial ryegrass swards on each of eight harvesting occasions during the 1994 growing season. The four silages, within a single harvest, were offered as the total diet at the maintenance level of feeding to 16 wether sheep in an 8-period change-over study with experimental periods of 3 weeks duration, in order to determine whole tract digestibility and urinary excretion of purine derivatives (PD). Silage dry matter (DM) and nitrogen (N) degradabilities were also examined in the rumen of four rumen-fistulated steers offered a medium quality silage and a concentrate supplement at a ratio of 60[ratio ]40 (silage[ratio ]concentrate) on a DM basis. The data presented are the mean results obtained across the eight harvests.There were no significant effects of inoculation on silage pH and ammonia-N/total-N across the unwilted and wilted materials. Inoculation of either the unwilted or wilted silages had no significant effect on microbial activity in the rumen of sheep, as indicated from excretion of urinary PD, or on silage DM or N degradability assessed with rumen-fistulated steers. However, inoculation significantly increased the digestibility of organic matter (1·7%, P<0·01), N (4·6%, P<0·001), energy (2·3%, P<0·01), neutral detergent fibre (1·5%, P<0·05) and acid detergent fibre (2·8%, P<0·001) in the silage. These increases in digestibility following inoculation, in general derived equally from both the unwilted and wilted silages. The results indicate that the increase in silage nutrient digestibility following inoculation probably reflects a more extensive digestion in the abomasum and intestine, rather than in the rumen.Wilting of grass prior to ensiling resulted in silages with significantly lower pH (5·4%, P<0·05) and ammonia-N/total-N (42·7%, P<0·001) across the untreated and inoculant-treated materials. Wilting also significantly increased (P<0·05) urinary PD-N output of sheep by 6·9% and silage DM degradability by steers by 1·6–2·4% across the untreated and inoculant-treated silages. However, there were no significant effects of wilting on silage N degradability and silage nutrient digestibility.

The effect of dietary fat and metabolizable energy supply on milk protein concentration of dairy cows

AbstractTo investigate the effect of dietary fat and metabolizable energy (ME) on milk protein concentration, an experiment was carried out using 12 multiparous early-lactation Holstein-Friesian dairy cows. Three diets were offered in a complete Latin-square change-over design, based on ad libitum access to grass silage. One of three concentrates was offered at a rate of 12 kg/day, each formulated to supply one of two levels of ME (12·1 and 13·6 MJ/kg dry matter (DM)) and one of two levels of fat (31 and a mean of 88 g acid hydrolysis ether extract per kg DM): low energy, high fat (LEHF); low energy, low fat (LELF); and high energy, high fat (HEHF). The concentration of milk protein was significantly higher from animals offered the LELF concentrate (32·5 v. a mean of 31·2 (s.e.d. 0·45) g/kg, P < 0·05), because of lower milk yields (31·0 v. a mean of 33·4 (s.e.d. 0·63) kg/day, P < 0·05). Animals offered the HEHF concentrate produced the highest yields of milk protein but their milk had the lowest concentrations of fat (32·5,34·4 and 31·9 g/kg for LEHF, LELF and HEHF respectively; s.e.d 1·07; P < 0·05 for difference between LELF and HEHF). Silage DM intake was significantly increased by animals offered the LEHF concentrate (9·1, 8·6 and 8·7 (s.e.d. 0·19) kg/day, P < 0·05 for differences between LEHF and the other two concentrates). Urinary purine derivative excretion, used as an index ofmicrobial protein supply, was highest from animals offered the LELF and HEHF concentrates, which both supplied similar amounts of fermentable ME. It is hypothesized that increased de novo synthesis offatty acids on the low fat diet reduced the availability of glucose for lactose synthesis, leading to reduced milk yields and hence increased milk protein concentrations.

Biogenic Amines in Silage, Apparent Postruminal Passage, and the Relationship Between Biogenic Amines and Digestive Function and Intake by Steers

A 4 × 4 Latin square experiment was conducted to examine abomasal passage of biogenic amines in steers fed silage and their related effects on intake, digestibility, and digestive function. Thirty percent of the dry matter (DM) in the diets consisted of alfalfa forage, which was fed as either hay or silage. The DM from alfalfa silage DM was substituted at 0, 33, 67, and 100% for DM from alfalfa hay and was fed to four ruminally and abomasally cannulated steers. The roughage component of the diet constituted 50% of the DM and consisted of 60% alfalfa silage or hay and 40% tropical corn silage. The concentrate was composed mainly of ground corn. The concentrations of putrescine and cadaverine in abomasal digesta increased as alfalfa silage in the diet increased. Abomasal recovery of biogenic amines, a product of their concentration in abomasal digesta and the passage of DM through the abomasum, was negatively correlated with intake. Abomasal recovery of most amines was 5 to 20% of intake. Abomasal recovery of cadaverine was correlated with depressed intake. Total DM intake was reduced 8.3 to 25.8% as the proportion of alfalfa silage in the diet increased. Frequency of reticular contractions, intake, ruminal DM digestibility, ruminal outflow, volatile fatty acids, and total tract DM digestibility decreased in steers fed diets that contained more alfalfa silage. Ruminal fluid pH and NH3 concentration increased in steers fed more alfalfa silage; however, mass and the DM percentage of ruminal contents decreased linearly. Postprandial insulin concentrations were quadratically related to the proportion of alfalfa hay or silage in the diet. Intraruminal metabolism of biogenic amines is extensive based on the relatively low quantities recovered in abomasal digesta; however, the amounts recovered in abomasal digesta were related to intake depression and associated physiological effects.

Effects of N application on agronomic and environmental parameters in silage maize production on sandy soils

The current nitrogen (N) use in silage maize production can lead to considerable N losses to the environment. Maize growers fear that a reduction of N inputs needed to minimize N losses might depress yields. The objective of this study was therefore to quantify: (1) the response of silage maize dry matter (DM) yields to N, (2) the economically optimal N reserve, and (3) the trade-off between silage maize DM yield and N losses. The indicators of N losses used in this study were the difference between N input and N uptake and the post-harvest residual soil mineral N. Regression models were used to fit DM yields and N uptakes of silage maize measured in 25 experiments on sandy soils in the Netherlands to the sum (SUMN) of the soil mineral N reserve (SMN early) in March–April, plus mineral N in fertilizer, plus ammonium N in spring-applied slurry. The values obtained for the economically optimal SUMN in the upper 30 and 60 cm of soil were, respectively, 173 and 195 kg N ha −1, when we assumed that the value of 1 kg fertilizer N equals the value of 5 kg silage DM. The economically optimal SUMN was not significantly related to the attainable DM yield. The apparent N recovery (ANR) of maize averaged 53% at the economically optimal SUMN. The ANR rose considerably, however, when N was applied at lower rates, indicating that N losses may be considerably smaller in less intensive maize cropping. When maize was fertilized at 100 kg N ha −1 below the economic optimum, the ANR was 73%, the difference between the mineral N input and the N crop uptake decreased by 57 kg N ha −1 and the soil mineral N residue at the end of the growing season (0–60 cm) decreased by 24 kg N ha −1. The associated reduction in DM yield averaged 16%. Fertilizer prices would have to be as much as four times higher to make maize growers spontaneously reduce the application rates by a 100 kg N ha −1, however. It is concluded that adjusting the N input to a level below the economically optimal rate can reduce the risks for N losses to the environment associated with conventional maize production, with a limited effect on silage yields.

Factors affecting water intakes of lactating dairy cows offered grass silages differing in fermentation and intake characteristics

AbstractThe objective of this study was to investigate the effects of silage characteristics on water intake of lactating dairy cows and to examine the prediction of water intake. Sixteen grass silages, differing in fermentation and intake characteristics, were offered ad libitum to dairy cows in early lactation supplemented with 7 kg/day of concentrate (13·3 MJ metabolizable energy per kg dry matter (DM) and 216 g crude protein per kg DM). Four silages were offered in each of four incomplete change-over design experiments, consisting of three 3-week periods. Water intakes were recorded through individual Kent water meters and press water bowls over the final week of each period. Tree (drinking) water intake ranged from 20·1 to 89·9 (mean = 45·2; s.d. = 12·96) I/day whilst total water intake (also including food water) ranged from 48·4 to 123·8 (mean = 87·3; s.d. = 14·12) I/day. Water intake increased with increasing silage DM concentration, however free water replaced silage water at a rate less than 1. Milk yield and silage D value (digestible organic matter, g/kg DM) were strongly positively correlated with free water intake (r = 0·751 and 0·595 respectively), though fermentation indices were not good single predictors of water intake. Further analysis revealed problems owing to collinearity within the predictors of water intake: DM intake, silage D value and milk yields being significantly correlated, as were pH and volatile fatty acids as a proportion of total fermentation acids. The ridge regression technique was used to reduce collinearity problems and produce stable equations. The best prediction equations for water intake involved a combination of both animal and analytical information: diet DM concentration, milk yield and silage pH. The use of fermentation information, whether from titration or high-performance liquid chromatography did not describe real variation in water intake beyond that described by silage pH. Free water intake was higher with higher diet DM concentrations, higher milk yields and higher silage pH.

Development and validation of methods for the trace determination of PCBs in biological matrices

A method was developed to determine trace concentrations of a range of individual PCB congeners in biological samples (grass, silage, cattle faeces and milk-fat) which were taken from rural or ‘background’ areas of the UK, in order to prepare a mass balance of PCBs in grazing, lactating cows. A simple milk-fat extraction method was compared to Soxhlet extraction and to whole milk extraction. Results indicated that simply boiling milk-fat in hexane with sodium sulphate present gave a comparable extraction of PCBs to other methods. A clean-up method was devised using acid treated silica gel followed by basic alumina chromatography. Grinding frozen grass or silage with sodium sulphate followed by Soxhlet extraction was found to be the most effective method for these matrices, whilst avoiding the potential contamination/loss of PCBs which can be incurred by air, oven or freeze drying. Soxhlet extraction of cattle faeces, after grinding with sodium sulphate, was found to be effective. A rigorous clean-up was devised which involved passing the extracts through silica gel and acid treated silica gel, followed by size exclusion chromatography (gel permeation chromatography, SEC). 13C 12 labelled PCBs were used as recovery standards, quantification was performed using GC-MS. A quality control regime and method validation results are presented. The milk analysis method gave within batch mean recoveries of 69 – 96%, and within batch standard deviations between 1 and 10%. The vegetation analysis method gave within batch mean recoveries of 91 – 116%, and within batch standard deviations between 1 and 11%. The batch to batch mean recovery for milk analysis was 90%, with an RSD of 2% for high spikes and 5% for low spikes; for vegetation analysis the batch to batch average recovery was 106%, with an RSD of 14% for high spikes and 11% for low spikes. ΣPCB concentrations (53 congeners) of 3900 ± 790 pg g −1 milk-fat, 1300 ± 420 pg g −1 dry matter (DM) cattle faeces, 630 ± 140 pg g −1 DM silage and 1350 ± 580 pg g −1 DM grass were found during the study.

Effect of duration of fasting period on short-term intake rates of lactating dairy cows

AbstractThe effects of duration of fasting on the short-term feeding behaviour of 12 grazing and 12 silage-fed lactating Holstein-Friesian dairy cows were examined. Four groups of three cows were rotated around fasting treatments of 1, 3, 6 or 13 h following a balanced Latin-square design. Herbage intakes for each treatment group were assessed over al-h period.As intended there were no significant differences in sward characteristics between the experimental plots grazed by cows from different treatment groups. However, total dry-matter (DM) intake, biting rate and DM intake per bite, measured over the 1-h grazing period, increased significantly when the duration offasting was extended from 1 to 6 or 13 h (P < 0·05). There were only minor differences in grazing behaviour following fasting durations ofl and 3, or 6 and 13 h.In a parallel study, undertaken to assess the influence offasting duration on appetite independently of grazing, four groups of three cows were housed indoors and offered 30 kg of a high quality grass silage. Silage DM intakes, measured over a 1-h period, increased significantly with extended fasting periods (P < 0·01), though silage DM intake was considerably lower than that of grazing cows for each fasting treatment.These results suggest that dairy cows grazing on good quality swards may be able to compensate for increased degree of hunger by increasing both biting rate and DM intake per bite to increase DM intake rate. Although the DM intakes of silage and grazed grass followed similar patterns of increasing intake with extended fasting duration, DM intake rates were considerably higher in grazing cows for each fasting treatment.

The Effect of Formic Acid with Formalin on Grass Silage Fermentation and the Performance of Dairy Cows

In the first experiment, perennial ryegrass with dry matter (DM) 260 g/kg and water-soluble carbohydrate (WSC) 140 g/kg DM was harvested as first-cut material on 25 May 1982. It was pre-wilted for 24 h prior to ensilage and treated with either a formic acid with formalin additive (WFF) at 4l/t or no additive (W) and ensiled in two adjoining covered 150 t bunker silos. Subsequently, both silages were satisfactorily fermented. Nevertheless, the pH, ammonia–N g/kg N and lactic-acid content were significantly lower and the residual WSC content significantly higher for WFF than W. Each silage was subsequently individually fed to ten Friesian and ten Holstein dairy cows, together with 10 kg/d of a compound feed containing 160 g/kg crude protein in a 70 d feeding trial. Additive treatment had no significant effect upon silage DM intake, milk output or composition. However, the daily liveweight losses of cows given WFF-treated silage were significantly higher than those given W. In the second experiment, perennial ryegrass (DM 180 g/kg and WSC 170–200 g/kg DM) harvested as first-cut material on 2 June 1983, was either cut and picked up within 20 min of cutting and treated with either the formic acid with formalin additive at 4l/t (NWFF) or no additive (NW); or wilted for a maximum of 24 h and treated with either the formic acid with formalin additive at 4l/t (WFF) or no additive (W). Wilting significantly increased subsequent silage DM. The pH of NW was significantly less than W, whilst the ammonia–N g/kg N of NWFF was significantly less than NW and W and that of W significantly higher than the other treatments. Additive treatment significantly increased the residual WSC content. Each silage was subsequently individually feed to 12 Friesian and 12 Holstein dairy cows together with 10 kg/d of a compound feed to 12 Friesian and 12 Holstein dairy cows together with 10 kg/d of a compound feed containing 160 g/kg protein in a 180 d feeding trial. The silage DM intake of WFF was significantly higher than NW. Silage treatment had no significant effect upon milk output or composition. The daily liveweight loss of cows given WFF-treated silage was significantly less than the other treatments, and the cows on NW had a significantly longer calving index than the other treatments. It is concluded that compared with non-additive-treated silage, formic acid with formalin applied at ensilage produced better fermented silage which, when subsequently given to lactating dairy cows, produced no significant increase in daily silage DM intake, milk output or composition, but had small significant effects upon liveweight change.

The Effect of Formic Acid, Formic Acid Salt and Formic Acid with Formalin on Silage Fermentation, Digestibility and Intake, and on Liveweight Change of Young Cattle

Abstract Data from four experiments conducted at ADAS Liscombe Research Centre during 1977–1982 were used to compare unwilted silage treated with either formic acid (FA), a complex formic salt (FS) and formic acid with formalin (FF) with non-additive-treated silage (C), made from herbage with dry matter (DM) 166 g/kg and water-soluble carbohydrate (WSC) 21 g/kg. Following ensilage, the DM content of C was significantly less than that of the other treated silages. Compared with C, the additive treatments significantly decreased pH, acetic acid, butyric acid, total short-chain fatty acids and total acid content and increased the WSC content. Compared with FA and FS, FF significantly increased the WSC content. DM losses from FA and FF treatment were significantly less than C but not FS. Additive treatment significantly increased silage DM intake and liveweight gain compared with C. It is suggested that additive treatment irrespective of the nature of the formic acid applied produced well-fermented silage, which when fed to growing cattle significantly increased both silage DM intake and liveweight gain compared with non-additive-treated silage.

The Effect of Formic Acid with Formalin Addition and Wilting on Silage Fermentation and Intake, and on Liveweight Change of Young Cattle

Abstract Data from seven experiments conducted at ADAS Liscombe Centre during 1980–1983 were used to compare formic acid with formalin-treated unwilted (FF) and wilted silage (WFF) with wilted non-additive-treated (W) silage made from herbage [dry matter (DM) of 172 g/kg and water-soluble carbohydrate (WSC) 114 g/kg DM]. Following ensilage, the DM content of FF was significantly less than W and WFF. Compared with W, WFF treatment significantly decreased silage pH, ammonia–N and butyric-acid content and significantly increased the residual WSC, whereas FF significantly reduced pH, ammonia–N, butyric acid, protein and ash content and significantly increased lactic acid, acetic acid and lactic acid expressed as a proportion of total acid content. DM losses were significantly higher for FF than from W or WFF treatments. W and WFF significantly increased subsequent silage DM intake compared to FF. Daily liveweight gains were, however, significantly higher on FF compared with W but not WFF treatment. It is suggested that FF treatment of unwilted silage produced well-fermented silage, which when fed to growing cattle had a lower DM intake, but higher liveweight gain than wilted silage, and that when compared with wilted silage (W) formic acid with formalin treatment (WFF) improved fermentation, but provided no significant benefit in terms of either silage DM intake or liveweight gain.

The effects of concentrate energy source on silage intake and animal performance with lactating dairy cows offered a range of grass silages

AbstractA partially balanced change-over design experiment was made to examine the effects of concentrate energy source on the voluntary food intake and animal performance of 50 lactating dairy cows offered a diverse range of grass silages. The silages were also offered as the sole diet to 10 dairy cows in a partially balanced change-over design experiment. A total of five silages were prepared. Silages A, B and D and silages C and E were harvested from primary regrowths and secondary regrowths respectively of predominantly perennial ryegrass swards. Herbage was ensiled either pre-wilted or unwilted and either untreated or treated with a bacterial inoculant or formic acid based additives. For silages A, B, C, D and E, dry matter (DM) concentrations were 473, 334, 170, 170 and 256 (s.e. 4·0) g/kg, pH values 4·42, 4·01, 4·88, 4·46 and 3·91 (s.e. 0·059), ammonia-nitrogen (N) concentrations 86, 88, 289, 182 and 135 (s.e. 10·6) glkg total N and in vitro DM apparent digestibilities 0·76, 0·76, 0·75, 0·73 and 0·75 (s.e. 0·009) respectively. When offered as the sole diet DM intakes were 14·1,14·7,10·5,10·1 and 11·5 (s.e. 0·50) kg/day. Five concentrates were formulated to contain similar concentrations of crude protein, effective rumen degradable protein (ERDP), metabolizable energy (ME) and fermentable ME (FME) but using different carbohydrate sources to achieve a wide range of starch concentrations. For the low and high starch concentrates, starch concentrations were 50 and 384 g/kg DM, and acid-detergent fibre concentrations were 128 and 75 g/kg DM respectively. The silages were offeredad libitumsupplemented with 10 kg concentrate per head per day. For silages A, B, C, D and E silage DM intakes were 10·6, 10·5, 8·5, 8·6 and 9·0 (s.e. 0·37) kg/day and milk yields 23·9, 28·1, 26·2, 26·1 and 25·0 (s.e. 0·76) kg/day respectively. Concentrate energy source did not influence (P > 0·05) silage DM intake, diet apparent digestibility or the yields of milk or fat plus protein. For concentrates containing 50, 131, 209, 310 and 384 g starch per kg DM, milk protein concentrations were 32·0, 32·2, 32·5, 33·0 and 33·6 (s.e. 0·13) glkg, milk fat concentrations were 44·5, 43·9, 43·8, 43·3 and 43·1 (s.e. 0·35) glkg and urinary allantoin concentrations 15·2,15·4, 17·0, 1.7·6 and 18·0 mmolll respectively. Increasing starch intake resulted in positive and negative linear relationships for milk protein (P< 0·01, R2 = 0·96) and fat (P< 0·01, R2 = 0·96) concentrations respectively. There were no significant concentrate energy source × silage type interactions on silage intake or yields of milk or fat plus protein (P > 0·05). However there was a concentrate energy source × silage type interaction on milk fat yield (P > 0·05). It is concluded that, with silages of varying fermentation and intake characteristics but similar apparent digestibility, there were no concentrate energy source × silage type interactions on food intake, milk composition or milk yield. Also concentrate energy source had no effect on silage DM intake or milk yield. However increasing starch intake linearly increased milk protein concentration, probably due to increased microbial protein synthesis and decreased milk fat concentration.

Effect of Additives on Grass Silage Fermentation and Effluent Production, and on Intake and Liveweight Change of Young Cattle

Abstract Data from 11 experiments, conducted mainly at ADAS Liscombe Research Centre during 1989–1992, were used to compare silages made with additives which included formic acid, an acid–salt-type additive, sulphuric acid, liquid inoculant and a cultured inoculant with a non-additive-treated control. The silages were made from herbage with dry matter (DM) 170 g/kg and water-soluble carbohydrate (WSC) 21 g/kg. Compared with the non-additive-treated silage, formic-acid treatment significantly reduced silage pH, ammonia–N, acetic acid, butyric acid, total short-chain fatty acid and total acid content and significantly increased the proportion of lactic acid expressed as a proportion of the total acids. The acid–salt-type additive significantly decreased pH, lactic acid, acetic acid, total short-chain fatty acids and total acid content and significantly increased WSC. Sulphuric acid significantly reduced pH and ammonia-N. The liquid inoculant had no significant effect upon any silage fermentation parameters, and the cultured inoculant significantly reduced pH and acetic acid and significantly increased the proportion of lactic acid expressed as a proportion of total acids. Effluent production was higher with acid treament, but the effect was not significant. The effluent from the acid–salt-type additive-treated silage had a significantly higher DM and WSC than the other treatments. The silage DM intakes of the formic acid (5·36 kg/d), sulphuric acid (5·29 kg/d) and the acid–salt-type additive (5·20 kg/d) were significantly higher than those of the untreated silage (4·76 kg/d), and the daily live-weight gains given by the acid–salt-type additive (0·71 kg/d) and formic acid (0·68 kg/d) treated silages were significantly higher than those of the untreated silage (0·58 kg/d). It is suggested that the improvements in silage preservation obtained from additive use at ensilage were closely reflected in terms of animal performance. The acid– salt-type additive and formic-acid treatments were most effective, the liquid inoculant and sulphuric acid inter mediate between the acid–salt-type additive or formic acid and untreated silage, whilst the cultured inoculant was similar to untreated silage.

Effects of tannins, formaldehyde and formic acid on total tract disappearance of DM, nitrogen and amino acids in grass silage

A major problem with grass is that during ensilage the proteins are degraded and nitrogen lost as non protein nitrogen. In the animal a disadvantage of grass silage is that the proteinaceous nitrogen is readily degraded in the rumen to ammonia. There is considerable evidence in the literature indicating that ruminal undegradable protein is a desirable component of some feeds (AFRC, 1993). This is valuable since proteins that by-pass the rumen may be digested in the intestine and the resultant amino acids absorbed. Tannins have been identified by other workers as suitable for the protection of protein in the rumen. However, there is some dubiety regarding the subsequent efficient release of protein in the intestine (McNabb et al., 1993). The effect of quebracho or mimosa tannins or formaldehyde or a combination of tannin/formate or formaldehyde/formate on silage total tract disappearance of dry matter (DM), nitrogen and total amino acids (TAA) was examined in this study.

Barley fibre and wet distillers’ solubles in the diet of growing cattle

Twenty-eight bulls were used in a 3 x 2 factorial design to study the effects of two by-products from the integrated starch-ethanol process, barley fibre and distillers’ solubles, as supplements for grass silage. The animals were divided into five blocks and slaughtered when the average live weight (LW) of each block reached 500 kg. The three energy supplements were barley (B), a mixture (1:1 on a dry matter (DM) basis) of barley and barley fibre (BF), and barley fibre (F), fed without (DS-) or with (DS+) wet distillers’ solubles (200 g kg-1 concentrate on DM basis). Concentrates were given at the rate of 95 g DM kg-1 LW0.6. Including barley fibre in the diet did not affect feed intake, but distillers’ solubles tended to increase both silage and total DM intakes as well as amino acids absorbed in the intestine and energy intake. The protein balance in the rumen increased with the inclusion of barley fibre (P

The effect of wilting grass prior to ensiling on silage intake of beef steers

Wilting of grass prior to ensiling has been widely adopted as a means of improving the fermentation quality of silage. However, the effects on intake have been variable. For example, with growing cattle, Rohr and Thomas (1984) reported that wilting increased silage dry matter (DM) intake by 0.09, while Steen (1984) reported an increase of 0.18. Similarly with lactating cattle, Rohr and Thomas (1984) reported and increase in intake in response to wilting of 0.04, while Patterson, Yan, Gordon and Kilpatrick (1997) observed an increase of 0.20. However, a range of additives were used in these studies and it is suggested that this may have caused variation in the fermentation quality of the unwilted silages which in turn may have affected the response to wilting. Consequently an experiment was designed to determine if the variability in the intake responses to wilting could be explained by differences in the fermentation characteristics of the unwilted silage.

Supply of nutrients and productive responses in dairy cows given diets based on restrictively fermented silage

The objective of this paper is to review research which has evaluated the feeding of dairy cows with diets containing large proportions of grass silage. In Finland, milk production systems evolved are based on the use of restrictively fermented silages. Higher potential yields, smaller production risks than with cereal grains, short grazing period and high digestibility of grasses grown in northern latitudes have facilitated this development. Factors affecting nutrient supply from these diets are discussed. Digestibility is determined mainly by the stage of maturity at harvesting and it is not markedly affected by the level of energy and protein supplementation. Intake of grass silage is influenced both by digestibility and fermentation characteristics. Efficiency of microbial synthesis is high in animals given diets based on restrictively fermented silage but rumen fermentation pattern is characterised by low molar proportions of propionate. Production responses to additional concentrate are relatively small, especially when the amount of concentrate exceeds 10 kg day-1. High substitution of silage dry matter (DM), negative associative effects on digestion and partitioning of energy towards body tissues account for small production responses. Protein supplementation has consistently increased milk protein yield but responses do not appear to be related to the level of milk production, silage crude protein content, amount of concentrate or stage of lactation. The new protein evaluation system provides an accurate prediction of protein yield with the typical Finnish dairy cow diets. The high slopes (ca. 0.5) between protein supply and milk protein yield within experiments suggest that protein supply is suboptimal and protein supplements are used with a high efficiency.

The effect of wilting grass prior to ensiling on silage intake of beef steers

Wilting of grass prior to ensiling has been widely adopted as a means of improving the fermentation quality of silage. However, the effects on intake have been variable. For example, with growing cattle, Rohr and Thomas (1984) reported that wilting increased silage dry matter (DM) intake by 0.09, while Steen (1984) reported an increase of 0.18. Similarly with lactating cattle, Rohr and Thomas (1984) reported and increase in intake in response to wilting of 0.04, while Patterson, Yan, Gordon and Kilpatrick (1997) observed an increase of 0.20. However, a range of additives were used in these studies and it is suggested that this may have caused variation in the fermentation quality of the unwilted silages which in turn may have affected the response to wilting. Consequently an experiment was designed to determine if the variability in the intake responses to wilting could be explained by differences in the fermentation characteristics of the unwilted silage.

Effects of and interactions between the extent of silage fermentation and protein supplementation in lactating dairy cows

Twelve Ayrshire cows were used to study the effects of and interactions between extent of silage fermentation and level of protein supplementation on silage intake and milk production. Experimental design was a cyclic change-over with six dietary treatments, with two replicate blocks of six cows and four 3-week periods. Dietary treatments in a 2 x 3 factorial arrangement consisted of two wilted silages treated with either a formic acid-based (FA) 5 l/t or a bacterial inoculant additive (I) and three levels of protein supplementation obtained by fish meal (FM) inclusion (0, 60 and 120 g/kg concentrate). Grass silage was given ad libitum and concentrates were offered at a rate of 10 kg/d. Both silages were well-preserved but I-silage was more extensively fermented than FA-silage. Feeding FA-silage decreased diet organic matter digestibility, particularly that of neutral detergent fibre, compared with I-silage. Inclusion of FM increased the digestibility of all dietary constituents. Dry matter (DM) intake of I-silage was lower than that of FA-silage but milk yield was not significantly affected. Restricting silage fermentation increased milk fat content, fat yield and energy corrected milk yield. FM inclusion increased silage DM intake, milk yield, milk protein content and yield. FM120 inclusion increased milk fat yield more with FA-silage than with I-silage, whereas the response in milk protein yield was greater with I-silage. Plasma glucose, plasma urea and milk urea concentrations were lower and blood β-hydroxybutyrate higher in cows given FA-diets than those given I-diets.