Changes in the distribution of nitrogen and plant enzymatic activity during ensilage of lucerne treated with different additives

Effects of formic acid, formaldehyde and two levels of tannic acid on changes in the distribution of nitrogen (N) and plant enzymatic activity during ensilage of lucerne (Medicago sativa) were studied. Lucerne [300 g dry matter (DM) kg^?1 forage] silages were prepared untreated (control) and with formic acid (4 g kg^?1 DM), formaldehyde (1 g kg^?1 DM) and two levels of tannic acid (20 and 50 g kg^?1 DM) as additives. Inhibition of proteolysis by formic acid was more effective than the other additives during the first 7 d of ensiling. Tannic acid was as effective at inhibiting production of non‐protein‐N, ammonia‐N and free amino acid‐N as formic acid and formaldehyde. However, increased concentrations of non‐protein‐N and free amino acid‐N in silage from day 1 to 35 of ensiling were less with the higher level of tannic acid than that in the control and other additive‐treated silages. Carboxypeptidase lost its activity slowly with increasing time of ensiling. At day 2, it still had 0·79 of the original activity in the control silage. After 21 d of ensiling, high levels of carboxypeptidase activity, proportionately 0·41, 0·49, 0·10, 0·35 and 0·30 of the original activity, remained in the control silage, and silages made with formic acid, formaldehyde, and low and high levels of tannic acid respectively. There were higher levels of activity of acid proteinase in formic acid‐treated silage than in the control silage until day 2 of ensilage indicating that the reduction of proteolysis by formic acid was probably due to acidifying the forage below the pH optima of plant protease. Aminopeptidase activity in all silages declined rapidly after ensiling.     

Alpha‐tocopherol and β‐carotene in legume–grass mixtures as influenced by wilting,ensiling and type of silage additive

Effects of wilting, ensiling and type of additive on α‐tocopherol and β‐carotene contents in legume–grass mixtures were examined. Swards of birdsfoot trefoil + timothy (Bft + Ti), red clover + timothy (Rc + Ti) and red clover + meadow fescue (Rc + Mf) were harvested as a first regrowth in August 2005. Forage was wilted to a dry‐matter (DM) content of 273 g kg^?1 and ensiled without additive or with an inoculant or acid. Wilting decreased α‐tocopherol concentration by 30% in the Bft + Ti mixture (P = 0·015). Untreated Bft + Ti silage had higher α‐tocopherol content than red clover silages (56·9 vs. 34·2 mg kg^?1 DM; P = 0·015). The α‐tocopherol concentration of Bft + Ti forages increased during ensiling from 41·1 mg kg^?1 DM in wilted herbage to 56·9, 65·2 and 56·8 mg kg^?1 DM in untreated, inoculated and acid‐treated silage respectively (P = 0·015). The inoculant increased α‐tocopherol content in the red clover silages (50·1 vs. 34·2 mg kg^?1 DM; P = 0·015) compared with untreated red clover silages. Red clover mixtures had lower β‐carotene content than Bft + Ti (32·3 vs. 46·2 mg kg^?1 DM; P = 0·016), averaged over treatments. In conclusion, wilting had small effects but the use of bacterial inoculant as an additive and a Bft + Ti mixture increased α‐tocopherol concentration in the silage.     

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.     

Effluent production from grass silages treated with additives and made in large-scale bunker silos

Data from twenty experiments, conducted at ADAS Research Centres in England and Wales during 1986–92, were used to determine effluent production from additive-treated grass silages made in large-scale bunker silos. The additives compared were formic acid at 4·0 l t^–1, rolled barley at 44·0 kg t^–1, dried molassed sugar beet feed at 40·0 kg t^–1 and liquid inoculants at 2·2 l t^–1 together with a non-additive-treated control. The silages were made from herbage with an average dry-matter (DM) content of 177 (s.e. 3·8) g kg^–1 and water-soluble carbohydrate content of 140 g kg^–1 DM. Average silage toluene DM content was 213 (s.e. 3·8) g kg^–1. The formic acid and sugar beet feed silages were both well fermented, whereas the other silages were less well fermented. Effluent produced was determined as either effluent production (l t^–1 grass ensiled) during the 52-d period in which it was measured or peak flow (l h^–1) during the first 2 d of ensilage. Compared with non-additive-treated silage, dried molassed sugar beet feed significantly reduced both effluent production (27%) and peak flow (36%). Formic acid significantly increased peak flow (51%), but had little effect upon effluent production, and significantly reduced effluent N and lactic acid content. Barley and inoculant treatment had no significant effect upon effluent production. In general, poor relationships were found between DM content and effluent production. Nevertheless for silages, except those treated with absorbents or formic acid, a significant (P < 0·001) negative relationship between silage effluent production (l t^–1 grass ensiled) and the DM (g kg^–1) content of the ensiled grass was found.     

The effect of stage of perennial ryegrass maturity at harvesting, fermentation characteristics and concentrate supplementation, on the quality and intake of grass silage by beef cattle

Abstract Two experiments were carried out in consecutive years to examine the influence of cutting date and restricting fermentation by carboxylic acid treatment on the nutrient intake from grass silage by beef cattle. In year 1, four cutting dates during July and August after a primary growth harvest and, in year 2, five cutting dates of primary growth between mid‐May and early July were examined. Herbage was ensiled either untreated or treated with high levels of acid additive (‘Maxgrass’, mean 8·6 l t^?1). Ninety‐six (year 1) or forty‐eight (year 2) continental cross steers were used in partially balanced changeover design experiments with each silage type either unsupplemented or supplemented with 4·5 (year 1) or 5·5 (year 2) kg concentrates head^?1 d^?1. Silage digestibility declined significantly between initial and final harvest dates (P < 0·001), whereas silage dry‐matter (DM) and digestible energy (DE) intakes were significantly higher in the initial compared with final harvest dates in both years of the study (P < 0·01). Similarly, silage DM and DE intakes, and total DM intakes, of acid‐treated and unsupplemented silages were greater than those of untreated and concentrate supplemented silages, respectively (P < 0·001). The results indicate that earlier cutting dates, and addition of acid to herbage before ensiling, can increase silage DM intake by beef cattle.     

Apparent digestibility and nitrogen utilization of diets based on maize silage harvested at three stages of maturity and fed to steers

Advancing maize crop maturity is associated with changes in ear‐to‐stover ratio which may have consequences for the digestibility of the ensiled crop. The apparent digestibility and nitrogen retention of three diets (Early, Mid and Late) containing maize silages made from maize of advancing harvest date [dry matter (DM) contents of the maize silages were 273, 314 and 367 g kg^?1 for the silages in the Early, Mid and Late diets respectively], together with a protein supplement offered in sufficient quantities to make the diets isonitrogenous, were measured in six Holstein–Friesian steers in an incomplete Latin square design with four periods. Dry‐matter intake of maize silage tended to be least for the Early diet and greatest for the Medium diet (P = 0·182). Apparent digestibility of DM and organic matter did not differ between diets. Apparent digestibility of energy was lowest in the Late diet (P = 0·057) and the metabolizable energy concentrations of the three silages were calculated as 11·0, 11·1 and 10·6 MJ kg^?1 DM for the Early, Medium and Late diets respectively (P = 0·068). No differences were detected between diets in starch digestibility but the number of undamaged grains present in the faeces of animals fed the Late diet was significantly higher than with the Early and Mid diets (P = 0·006). The apparent digestibility of neutral‐detergent fibre of the diets reduced significantly as silage DM content increased (P = 0·012) with a similar trend for the apparent digestibility of acid‐detergent fibre (P = 0·078). Apparent digestibility of nitrogen (N) was similar for the Early and Mid diets, both being greater than the Late diet (P = 0·035). Nitrogen retention did not differ between diets. It was concluded that delaying harvest until the DM content is above 300 g kg^?1 can negatively affect the nutritive value of maize silage in the UK.     

A new sterilization and inoculation method in silage research

The study aimed at evaluating an effective sterilization–inoculation technique to facilitate silage research on the effect of forage microflora on fermentation variables. The sterilization effect of heating at 60°C for 3 h + 103°C for 15 h was tested on samples of grass, grass–clover, white clover and maize, pre‐dried at 60°C to a dry‐matter (DM) content >900 g kg^?1. The ensilability of treated samples, reconstituted to original DM concentration (250–390 g kg^?1), was assessed by inoculation with microfloras extracted from the original samples. Microfloral inoculants were obtained by a combination of centrifugation (15 500  g for 40 min) and filtration (0·45 and 0·22 μm pore sizes) of the supernatant. The sterilization treatment effectively sterilized the forage samples but decreased water soluble carbohydrates by 49% and N buffer solubility by 22% and increased the acid detergent insoluble N proportion of total N by 53% (P < 0·05). The reconstituted silages had 18% less lactic acid, 20% less ethanol and 37% less ammonia‐N (P < 0·05), but volatile fatty acids and 2,3‐butanediol did not differ from the untreated silages (P > 0·05). Counts of lactic acid bacteria, enterobacteria, clostridia, yeasts and moulds in the two silage treatments were also similar (P > 0·05). It is concluded that, despite causing chemical and physical alterations, the sterilization–inoculation technique evaluated could be a useful tool for future studies on the effects of microflora on ensiling results.     

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.     

Influence of maceration at cutting on lactic acid bacteria populations, silage fermentation and voluntary intake and digestibility of precision-chopped lucerne silage

Laboratory experiments with lucerne (Medicago sativa) have shown that maceration at cutting improves silage fermentation. Samples taken during wilting and after various ensiling periods were analysed for lactic acid bacteria (LAB) numbers and indices of silage fermentation. In Experiment 1, in which maceration was tested in unwilted and wilted lucerne, there was an additive effect of maceration and wilting on LAB numbers at ensiling, thus LAB numbers were approximately 108 colony-forming units (cfu) g^?1 fresh crop for wilted, macerated forage compared with 103 cfu g^?1 fresh crop for unwilted, unmacerated forage at ensiling. Initially, maceration reduced pH (P < 0·001) and increased lactic acid (unwilted comparison only; P < 0·001) and insoluble N (wilted comparison only; P < 0·001) concentrations. After 70 d ensiling, beneficial effects of maceration were associated only with the wilted silage. In Experiment 2, macerated lucerne was compared with unmacerated material, which was either ensiled after a wilting period of similar length or after wilting had proceeded to the same DM concentration as in the macerated forage. During wilting, LAB numbers were significantly higher in macerated than unmacerated forage (P < 0·05). This was also the case during the first 16 h of ensiling (P < 0·01). A decline in pH was observed earlier in macerated silage. Two days after ensiling, lactic acid concentration was higher in macerated silage (P < 0·05), but insoluble N concentration was not different. In a third experiment, unconditioned forage was compared with forages ensiled after regular conditioning or maceration. Although drying rate over 30 h was not influenced by degree of conditioning, LAB numbers during wilting increased with the degree of conditioning. In silages made from these treatments after 6 h wilting, there were no major effects on fermentation characteristics. In a fourth experiment, digestibility and voluntary intake of precision-chopped silage were measured in sheep and found not to be increased by maceration. It was concluded that maceration per se resulted in marginal improvements in fermentation; however, when maceration also increased DM concentration, fermentation was markedly improved. In these precision-chopped silages, maceration had no effect on intake or digestibility.     

The effect of cell wall degrading enzymes or formic acid on fermentation quality and on digestion of grass silage by cattle

A first cut of timothy, treated with water (untreated), formic acid (FA), cellulase + lactic acid bacteria (CB), cellulase + hemicellulase (CH) or cellulase + hemicellulase + a lignin-modifying enzyme (CHL), was ensiled in pilot-scale silos. Silages, except CB, were fed to four male cattle, each equipped with a rumen and duodenal cannula, in a digestibility trial designed as a 4 × 4 Latin square. The animals were fed a diet of 400 g of concentrate and 600 g of silage at a level of 70 g DM kg^?1 live weight (LW^0·75). All enzyme-treated silages were well-preserved with a more extensive fermentation than in FA silage. The quality of untreated silage was poorer as indicated by higher pH and ammonia-N content. The amount of effluent from enzyme-treated silages ranged from 116 to 127 g kg^?1; for FA and untreated silages values were 101 g kg^?1 and 80 g kg^?1, respectively. Total DM losses from enzyme-treated silages were higher than from FA silage (P < 0·05). No significant differences were noticed between silages in the apparent digestibility of organic matter (OM), neutral-detergent fibre (NDF), acid-detergent fibre (ADF) or nitrogen (N). The apparent digestibility of cellulose was higher with enzyme-treated silages than with FA silage (P < 0·05). The values for microbial N flow at the duodenum were 80·0, 91·9, 80·7 and 70·5g N d^?1, and for the efficiency of rumen microbial N synthesis 38·6, 47·6, 36·9 and 32·5 g N kg^?1 OM apparently digested in the rumen for untreated, FA, CH and CHL silages, respectively. In the rumen the molar proportion of propionate was higher (P < 0·01) and that of butyrate lower (P < 0·01) with enzyme-treated silages when compared with FA silage. The proportion of butyrate was also lower with untreated than with other silages (P < 0·01). The rumen residence time of NDF and ADF was longer (P < 0·05) with enzyme-treated silages than with FA silage.     

Re‐ensiling and inoculant application with Lactobacillus plantarum and Propionibacterium acidipropionici on sorghum silages

Re‐ensiling of previously ensiled forage has been a common practice in Brazil, and the use of inoculants may provide a means of reducing dry‐matter (DM) loss. This study aimed to determine the effect of re‐ensiling and the use of microbial inoculants on the quality of sorghum silage. Treatments were presence/absence of an inoculant (Lactobacillus plantarum and Propionibacterium acidipropionici) in the silage, and the re‐ensiling, or not, of the material after 24 h of exposure to air, and these were tested in a factorial 2 × 2 design. Losses due to gas, effluent and total DM were assessed, as were the fermentation characteristics, chemical composition, aerobic stability, and aerobic counts of microorganisms. Effluent loss was higher in re‐ensiled silage, and these silages had lower lactic acid content and higher levels of acetic and propionic acids. The in vitro DM digestibility was lower in the re‐ensiled sorghum silages. The re‐ensiled silage had higher aerobic stability. The inoculant only increased the acetic acid content of the silage. The re‐ensiling of sorghum silage increased effluent loss by 71·2%, and reduced DM digestibility by 5·35%. The use of inoculant did not influence the quality of sorghum silage.     

Effect of two additives on the fermentation,in vitro digestibility and aerobic security of Sorghum–sudangrass hybrid silages

Two additives (Silo Guard (SG) and propionic acid (PA)) were tested for their effects on the quality and aerobic security of sorghum–sudangrass hybrid silages (JC‐1 and WC‐2). Two sorghum–sudangrass hybrid varieties were harvested for ensiling without additives (CK) or after the following treatments: SG at 0·5% of fresh forage or PA at 0·5% of fresh forage, with three replicates per treatment. The addition of SG and PA both affected the fermentation quality and chemical composition of the silages by lowering pH and NH₃‐N/TN and increasing lactic acid, the LA/TA ratio, WSC and CP concentrations compared with the untreated silages. In vitro DM digestibility (IVDMD), in vitro NDF digestibility (IVNDFD) and in vitro CP digestibility (IVCPD) were increased by SG in the JC‐1 silages and WC‐2 silages. Both additives improved the aerobic stability of sorghum–sudangrass hybrid silages. Furthermore, the additives reduced the mould counts and the aflatoxin and zearalenone levels compared with the untreated silages following aerobic exposure. Therefore, ensiling two sorghum–sudangrass hybrid varieties resulted in high‐quality silages. The addition of SG and PA improved silage quality, in vitro digestibility and aerobic security.     

Nitrogen fertilizer application and developmental stage affect silage quality of timothy (Phleum pratense L.)

Crop composition at harvest affects the ensiling process and the resulting silage quality. The objectives of this study were to determine: (i) the effect of annual N‐fertilizer application (0, 60, 120 and 180 kg N ha^?1) and developmental stage (stem elongation, early heading, late heading and early flowering) on the ensiling properties and silage quality of the spring regrowth of timothy (Phleum pratense L.) at two sites for 1 or 2 years, and (ii) the relationship between ensiling properties of the forage and the quality of the resulting silage. Laboratory silos with wilted forage at approximately 350 g dry matter (DM) kg^?1 of fresh matter were prepared at each harvest and opened 150 d later for silage analysis. Higher rates of N‐fertilizer application decreased the concentration of water‐soluble carbohydrates (WSC), increased the buffering capacity (BC) and nitrate concentration, and decreased the ratio of WSC:BC, primarily in the early stages of development. The ensiling properties of timothy were, therefore, less favourable when high rates of N fertilizer were applied. Silage pH generally increased with increasing rates of N‐fertilizer application; this increase was particularly evident at the first three developmental stages at one site in 1 year. Non‐protein N (NPN) and soluble N concentrations of the silages increased with increased rates of N‐fertilizer application at the first three developmental stages but decreased at early flowering. Ammonia‐N concentration in the silages increased by 0·85, 0·56 and 0·67 when rates of N‐fertilizer application were 60, 120 and 180 kg ha^?1, respectively, compared with that when no N fertilizer was applied. Significant correlations between the composition of the forage ensiled and silage quality variables were found at sites in individual years but, when all data were combined, WSC concentration and BC, and their ratio in the forages, were not correlated with pH, and soluble‐N and ammonia‐N concentrations of the silages, and were weakly correlated with NPN and free amino acid‐N concentrations of the silages. Silage quality was reduced by increased N‐fertilizer application, primarily at the early developmental stages, and this can be attributed to a reduction in WSC concentration and an increase in BC of the forage. Water‐soluble carbohydrate concentration, BC, and their ratio, however, were poor predictors of silage quality.     

The influence of grass and maize silage quality on apparent diet digestibility, metabolizable energy concentration and intake of finishing beef cattle

The effects of offering a range of grass silages and mixtures of grass and maize silages on the intake of beef cattle were studied. Four grass silages (GS1, GS2, GS3 and GS4) were used. Grass silage 1 was ensiled from a second regrowth in mid‐late September and treated with an inoculant additive. Grass silages 2, 3 and 4 were ensiled, without additive, from a primary regrowth harvested in early July, late May and mid‐June respectively. Wilting periods were 8, 30, 36 and 36 h for GS1, GS2, GS3 and GS4 respectively. Grass silages 1, 2 and 3 were precision chopped and ensiled in bunker silos, while GS4 was ensiled in round bales. The DM content (g kg^?1) and starch concentration (g kg^?1 DM) of the three maize silages (MS1, MS2 and MS3) used were 256 and 128, 256 and 184, and 402 and 328 for MS1, MS2 and MS3 respectively. Seventy‐two Charolais and Limousin cross‐bred steers were used in a changeover design with two 4‐week periods. The study consisted of sixteen treatments incorporating the four grass silages fed alone and with the three maize silages arranged as a 4 × 4 factorial design. The grass silage and maize silage mixtures were offered in a ratio of 0·60:0·40 (DM basis) once daily using individual Calan gates. All silages were offered ad libitum with 3 kg per head per day of a concentrate supplement. Dry matter and metabolizable energy (ME) intakes were highest with diets based on grass silage GS4 compared with diets containing the other grass silages. Metabolizable energy intakes of diets containing no maize silage, and those based on MS1 and MS2, were similar (P > 0·05) but lower than that of diets containing MS3. Only limited increases were found in DM and ME intakes with the inclusion of maize silage in grass silage‐based diets while offering high‐quality grass silage (assessed in terms of DM content, and fibre and N concentrations) promoted high voluntary intakes.     

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.     

Unwilted and prewilted grass silage for finishing bulls*

Three silages were prepared from perennial ryegrass; unwilted without additive (UW), unwilted treated with 3·5 litres commercial (85%) formic acid (UWA) and prewilted without additive (WN) with dry matter (DM) concentrations of 189, 209 and 328 g kg⁻¹ respectively. The three silages were offered ad libitum in a 348-d feeding experiment to three groups of eight Belgian white-blue bulls with an initial live weight (LW) of 277 kg. The concentrate (47 g digestible crude protein (CP) kg⁻¹) supplementation was 7·5 g (kg LW)⁻¹. Acid treatment (UWA) slightly improved digestibility of all silage nutrients except CP, whereas wilting generally slightly decreased digestibility of the nutrients except DM and ether extract. The daily LW gain averaged 912 g and was not significantly different on the three different treatments. DM intake per (kg LW)^0.75 was higher with the UWA silage, 69·3 g, and with the WN silage, 71·6 g, than with the UW silage, 65·8 g. However, this difference in DM intake was not reflected in either daily LW or carcase gain. The DM of UW silage was more efficiently utilized than DM of UWA or WN silage.     

Separating the effects of forage source and field microbiota on silage fermentation quality and aerobic stability

This study attempted to separate the effects of forage source and field microbiota on silage fermentation quality and aerobic stability. Single samples of grass, red clover and maize were used. Field microbiota was obtained by centrifugation of microbial suspensions of the three samples. The intact forages were dried and sterilized by heating at 60°C for 3 h + 103°C for 15 h, inoculated in a 3 (forage) × 3 (inoculum) design and reconstituted to a dry‐matter level of 400 g kg^?1 before ensiling. After ensiling for 71 d, subsamples were subjected to an 8‐d aerobic stability test, which included temperature and pH measurements. Bacterial community analysis was performed on samples before and after ensiling by 16S rRNA gene amplicon sequencing. Forage source had a marked effect on the levels of lactic acid, acetic acid, ammonia‐N and 2,3‐butanediol, but microbiota source only affected the acetic acid concentration. The forage and microbiota as well as their interactions affected silage stability variables. The maize microbiota improved silage stability, whereas silages made from the maize forage had the poorest stability. Bacterial community analysis revealed higher abundance of lactic acid bacteria on the maize forage, with Lactococcus and Leuconostoc being the dominant genera. These preliminary results suggested that fermentation quality is mainly affected by forage source, whereas the aerobic stability is affected by both forage and field microbiota.     

Effects of intercropping and fertilizer application on the yield and nutritive value of maize and amaranth forages in Nigeria

Maize and amaranth forages, produced during the wet season, have the potential to bridge the gap in forage supply to ruminants during the dry season in Nigeria. In two growing seasons (2006 and 2007), effects of intercropping and fertilizer application on dry matter (DM) yield and chemical composition of forages, and land use efficiency, were studied in two experiments. The digestibility of sun‐dried or ensiled maize, amaranth or maize–amaranth mixtures was measured using West African dwarf sheep in a third experiment. Maize showed a higher response to fertilizer application than amaranth or maize–amaranth mixtures. With fertilizer application, DM yield varied significantly (P < 0·05) between species and intercropped mixtures. Dry matter yield ranged from 7·1 (amaranth) to 12·6 t ha^?1 (maize) in 2006 and 6·9 (amaranth) to 11·3 t ha^?1 (70:30 maize–amaranth population mixture) in 2007. Crude protein (CP) concentration of whole plants ranged from 99·0 (maize) to 227·0 g kg^?1 DM (amaranth). Dry matter digestibility values of sun‐dried maize, sun‐dried maize:amaranth 50:50 mixture, sun‐dried amaranth, ensiled maize, ensiled maize:amaranth 50:50 mixture and ensiled amaranth were 0·718, 0·607, 0·573, 0·737, 0·553 and 0·526 respectively. Intercropping increased forage yield and land use efficiency compared to amaranth but had no yield advantage over maize. Although DM digestibility of maize was higher than that of amaranth or the maize:amaranth mixture, digestible CP yield ha^?1 was higher with amaranth in the cropping mixture, showing that amaranth could complement maize in systems where CP is the limiting factor to livestock production.     

The effects of lactic acid bacteria on the fermentation,aerobic stability and nutritive value of maize silage

Maize was harvested at one‐third milk line (297 g kg^?1 DM) stage. All inoculants were applied at 1 × 10⁶ cfu g^?1 of fresh forage. After treatment, the chopped forages were ensiled in 1·5‐L anaerobic jars. Three jars per treatment were sampled on days 2, 4, 7, 12 and 90 after ensiling, for chemical and microbiological analysis. Homofermentative LAB‐inoculated silages had lower pH and higher lactate:acetate ratio (except for Lactobacillus plantarum/Pediococcus cerevisiae and L. plantarum/Propionibacterium acidipropionici) than the control and both heterofermentative LAB‐inoculated silages. Both L. buchneri inhibited yeast growth and CO₂ production during exposure of silage to air. The L. plantarum/P. cerevisiae, L. plantarum (Ecosyl) and L. plantarum/Enterococcus faecium‐inoculated silages had higher dry‐matter digestibility than the control and L. buchneri‐inoculated silages. Inoculants did not affect digestibility of neutral detergent fibre, except for L. buchneri (Biotal), organic matter nor ME content of silages. The LAB silage inoculants generally had a positive effect on maize silage characteristics in terms of lower pH and shifting fermentation toward lactate with homofermentative LAB or toward acetate with L. buchneri. The use of L. buchneri can improve the aerobic stability of maize silages by the inhibition of yeast activity.     

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.