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.     

Effectiveness of chopped lucerne hay as a moisture absorbent for low dry‐matter maize silage: Effluent reduction,fermentation quality and intake by sheep

This study determined effects of addition of lucerne hay (LH) as moisture absorbent on effluent reduction, fermentation and subsequent intake of maize (corn) silage by sheep. Treatments included maize forage ensiled without LH (LH0), with 50 g/kg LH (LH5) and with 100 g/kg LH (LH10) on a fresh weight basis. Silages were made in 150‐kg bags in triplicate. Upon opening, representative samples from each bag were taken twice weekly during a feeding trial and used for laboratory analyses in a completely randomized design. Silages were fed ad libitum to six ewes in a duplicated 3 × 3 Latin square design with 21‐day periods for intake and digestibility determination. Lucerne hay incorporation linearly increased DM, ash, water‐soluble carbohydrates, buffering capacity and pH of silages, while it linearly decreased ammonia nitrogen, acetic acid and ethanol concentrations (p < .05). Effluent volume linearly decreased from 33 ml/kg in LH0 to 0.8 ml/kg in LH10. Addition of LH resulted in a linear increase in intakes of organic matter and fibre in ewes, while digestibilities of these nutrients linearly decreased (p < .05). Lucerne hay addition improved fermentation parameters and resulted in increased intake of maize silage without having negative impact on aerobic stability.     

Chemical composition and nutrient digestibility of pearl millet (Pennisetum glaucum) fed to growing pigs

Pearl millet grown at two different locations in the U.S.A., pearl millet A (PMA) and pearl millet B (PMB), were analyzed for chemical composition and nutrient content and compared to corn. The two samples of pearl millet and corn were incorporated into diets and fed to 24 growing pigs in a metabolism trial to determine nitrogen and mineral balance and digestibilities of energy, fat and amino acids. Pearl millet (PMA and PMB) was found to be richer in crude protein, gross energy, ether extract, acid detergent fiber, amino acid profile and mineral content than corn. However, digestibilities of dry matter (corn, 86·8%; PMA, 80·5%; PMB, 82·0%) and energy (corn, 85·3%; PMA, 78·8%; PMB, 80·5%) were higher (P<0·05) for corn than either of the pearl millet samples. Fat digestibility was much higher in pearl millet than corn. Although nitrogen intake and absorption were higher (P<0·05) for pearl millet, the digestibility of nitrogen was similar for pearl millet and corn. Net protein utilization was lower (P<0·05) in pearl millet when compared to corn (corn, 44·8%; PMA, 34·6%; PMB, 39·9%). Digestibilities of the essential amino acids, arginine, threonine, valine, isoleucine and lysine were higher in pearl millet than corn. Phosphorus retention, expressed as a percentage of intake and absorption, was higher in corn than pearl millet. Calcium intake and absorption were similar for pearl millet and corn. Intake and absorption of magnesium and managanese were also similar in pearl millet and corn. Zinc and copper retention, when expressed as a percentage of intake, were higher in corn, but absorption for both minerals was similar in corn and pearl millet. Pearl millet was found to supersede corn in nutrient content and amino acid digestibility.     

Proteolysis and in situ ruminal degradation of lucerne ensiled with Cistus ladanifer tannins

The effects of ensiling lucerne with graded inclusion of Cistus ladanifer condensed tannins (CT) on in silo fermentative parameters, in vitro organic matter digestibility (IVOMD) and on in situ rumen degradability of dry matter (DM) and crude protein (CP) were studied. Lucerne forage ( Medicago sativa subsp. sativa ) was sprayed with different solutions of C. ladanifer CT extract in 60 ml of water in order for dose 0 (control), 40 (L40), 80 (L80) and 120 (L120) g of CT per kg of lucerne DM and was ensiled in lab‐scale silos. After 35 days, the silages were analysed for chemical composition, and the in situ ruminal degradability was determined in rams. The inclusion of CT in the silages caused an important dose‐dependent reduction in soluble‐N, NH₃‐N and a large increase in true protein content and N bound with neutral detergent fibre (NDF‐N), which indicates an effective proteolysis reduction during ensiling. Also, the rumen undegradable protein (RUP) increased linearly (P < 0.01) with CT inclusion. However, a linear decrease (P < 0.02) of 5%, 13% and 22% of IVOMD was observed for the silages L40, L80 and L120 respectively. The results obtained suggest that C. ladanifer CT can be used as silage additives to reduce proteolysis of high‐protein forages during ensiling. A level of CT of 40 g/kg DM seems to be the best compromise between the gains achieved by the protection of CP degradation in silo and in the rumen and the losses associated with the depression of the digestion and absorption.     

Effect of type of underlay film on fermentation profile,nutritional quality and estimated loss of organic matter in the outer layer of whole‐plant maize ensiled in large bunker silos

Losses of organic matter in the outer layers of bunker silos covered with conventional polyethylene (PE) plastic can be substantial due to oxygen transmission through the plastic top‐covering film during the post‐ensiling storage period. The effect of two silo covering materials, oxygen barrier (OB) film (45 μm thickness) and clear PE film (50 μm thickness), as underlays to a white‐on‐black PE plastic top cover (120 μm thickness), was assessed in the outer layer of whole‐plant maize silage stored in three large bunker silos in the People's Republic of China. Samples of the crop at harvest and of silage from the upper 45 cm layer at 5 months post‐ensiling, prior to removal of silage for feed‐out, were analysed for DM, fermentation profile and chemical composition. Loss of OM was estimated from concentrations of ash in the crop at harvest and in the silage. Differences between underlay films in silage fermentation profile were small. Silage protected with OB underlay film had higher mean concentration of starch (p < .008) and higher mean NDF digestibility (p < .003) than silage under PE underlay film. Concentrations of ash were lower (p < .001) for silage covered with OB film than for PE film in all three trials. Mean estimated losses of OM were 170 g/kg for OB underlay film and 232 g/kg for PE underlay film (p < .001), and whole‐silo estimated net economic benefits to OB underlay film ranged from 0.17 to 0.74 US $ per tonne fresh crop ensiled.     

Effects of including bioactive legumes in grass silage on digestion parameters,nitrogen balance and methane emissions in sheep

The aim of this work was to investigate the effects of feeding sheep with silage mixtures containing bioactive legumes on intake and digestive parameters. The bioactive legumes used were sainfoin (SF, Onobrychis viciifolia) and red clover (RC, Trifolium pratense), which contain condensed tannins (CT) and polyphenol oxidase respectively. Five treatments were assigned to two groups of sheep according to a replicated 5 × 5 Latin square design. The five types of silages tested were, on a dry matter (DM) basis: pure timothy grass silage (Phleum pratense, control, T), three binary mixtures of T‐SF, T‐RC and RC‐SF (500 g/kg each) and a ternary mixture of T‐RC‐SF (500, 250 and 250 g/kg respectively). The daily voluntary DM intake of silage mixtures containing both SF and RC was greater than for pure T silage, while the presence of SF resulted in lower organic matter digestibility compared to pure T. The rumen disappearance rate measured in situ increased linearly with the presence of SF and RC in silage. The nitrogen (N) digestibility was greater for pure T and T‐RC than for T‐SF, and the amount of N retained daily by the animals was greater for RC‐containing silages than for T and T‐SF. The methane (CH₄) yield was greater for pure T than for the silage mixtures containing SF. We conclude that the presence of RC in silage could boost performances through intake and N retention, while SF‐based mixtures appear to have reduced negative environmental impacts through the reduction of CH₄ emissions.     

A meta‐analysis examining lactic acid bacteria inoculants for maize silage: Effects on fermentation,aerobic stability,nutritive value and livestock production

A database containing 140 articles published in journals (731 treatment means evaluated) was used to examine the effect of different lactic acid bacteria (LAB) on fermentation, chemical composition and aerobic stability of maize (corn) silage. Compared with the control, dry matter (DM) loss increased by 8% and 50% (p < .01) due to inoculation of maize silage with either homolactic LAB (^hoLAB) or heterolactic LAB (^heLAB). In vitro DM digestibility of maize silage increased only with ^hoLAB inoculation (+2.22%; p < .01). The ^heLAB inoculation increased (p < .01) the aerobic stability of maize silage by 71.3 hr. To investigate the effect of silage inoculation on livestock production, a second database comprising 35 articles [99 treatment means evaluated based on results from 648 cattle (429 beef cattle and 219 dairy cows) and 298 sheep] was used. Inoculation of maize silage with either ^hoLAB or ^heLAB did not affect milk yield (p > .05), but their combination (^mixLAB) depressed milk yield (–2.5 kg/day; p < .01). Inoculation with ^hoLAB increased DM intake in sheep (+0.15 kg/day; p = .02), but decreased it in beef cattle (–0.26 kg/day; p = .01) without affecting average daily gain for both sheep and beef cattle (p ≥ .06). In conclusion, fermentative loss increased regardless of the bacterial inoculant used, while aerobic stability increased mainly by using ^heLAB. Benefits from ^hoLAB inoculation on animal performance were noted only for feed intake in sheep, while productive performances of dairy cows and beef cattle were not improved.     

Effect of compaction,delayed sealing and aerobic exposure on forage choice and short‐term intake of maize silage by goats

Forage choice and intake by ruminants depend on various factors. This study aimed to determine the effects of compaction, delayed sealing and aerobic exposure on forage choice and short‐term dry‐matter intake (DMI) of maize silage by goats. Whole‐crop maize (277 g/kg dry matter [DM]) in 120‐L silos was compacted at either low (194 kg DM/m³) or high (234 kg DM/m³) density, and sealed immediately at day 0 or with a delay at day 2 or day 4 post‐filling, making a total of six treatments. After ensiling for at least 175 days, silages were exposed to air for 6 days. In 2‐day intervals, silages were sampled for chemical analyses and were vacuum‐stored for use in preference trials. During the experimental phase, each possible two‐way combination of the aerobically exposed silages (days 0, 2, 4 and 6 post‐opening) of the treatments and lucerne hay was offered as free choice to goats (n = 5) for 3 hr. Exposing silages to air for >4 days post‐opening caused strong avoidance and lowest intakes. Under the conditions of the study, aerobic exposure after ensiling had a more pronounced effect on silage preference and short‐time DMI than compaction and delayed sealing. Increasing fibre fractions, a deteriorating microbial status and poor silage sensory properties, probably caused by a combination of different fermentation products, can be considered for decrease in preference.     

Grass silage as a basic feed for store lambs. 1. Effect of wilting, chop length and stage of maturity of grass silage on intake and performance of store lambs

Two experiments were carried out with grass silages cut at a leafy (Experiment 1) and a more mature (Experiment 2) stage of growth to evaluate the effect of wilting and chop length on silage intake and performance of store lambs. In each experiment, the herbage was cut with a rotary mower and was either ensiled within 24 h as unwilled silage (U) or wilted for 1–3 d (W). Each silage type was harvested with either a double-chop harvester (D) or a precision-chop harvester (P). All silages were treated with formic acid at 3 1 t^?1 and were well preserved. The silages were fed ad libitum to Suffolk crossbred store lambs (twenty-four lambs per treatment) without any supplement over a period of 8 or 9 weeks. Wilting of the silages had little effect on silage intake (797 vs. 809g dry matter (DM) d^?1) or on lamb performance in Experiment 1. In Experiment 2, wilting of the D silage increased silage DM intake (589 vs. 534 g DM d^?1; +10%) and reduced the extent of liveweight losses. Wilting of the P silage reduced silage intake (770 vs. 791g DM d^?1; -3%) and reduced liveweight gains. In Experiment 1 intakes of the D silages were 650–667g DM d^?1 and just maintained lamb live weights. Intakes of the P silages were 39–49% higher than the D silages (927–968 g DM d^?1) and increased liveweight gains. In Experiment 2 intakes of the D silages were 534–589 g DM d^?1 and resulted in a loss in lamb live weight. Precision-chopping increased silage intakes by 31–48% (770–791 DM d^?1)in Experiment 2 and improved lamb liveweight gains. Lamb performance was higher on the UP silage than on the WP silage. The rumen retention lime (RRT), estimated from the rumen contents of the lambs at slaughter and their silage intake before slaughter, was much shorter for the lambs fed on the P silages (12.6–20.6 h) than those fed on the D silages (21.4–29.3 h) in each experiment. Silage intake and liveweight gain were positively related to silage in vivo DM digestibility (DMD), whereas RRT was negatively related to DMD. However, there were distinct differences between the P and D silages in the elevation and, to a lesser extent, in the slope of the regression lines, indicating that intake of D silage was limited by factors other than the digestibility of the silage The results of this study show that the chop length of grass silage had a far greater effect on intake and on lamb performance than silage digestibility, whereas wilting had little or no effect.     

Effects of shredding on silage density and fermentation quality

The effects of shredding forages on the density and fermentation quality of the resulting silages were studied. Lucerne (Medicago sativa L.), red clover (Trifolium pratense L.), perennial ryegrass (Lolium perenne L.) and a grass–clover mixture were harvested and wilted indoors for 1–2 days. The dry‐matter content of the forages after wilting was 192 g/kg, 192 g/kg, 237 g/kg and 214 g/kg respectively. The forages were then either unprocessed or shredded once (1×) or four (4×) times using a novel laboratory shredder and were ensiled in laboratory‐scale silos. Fermentation was terminated after either 50 or 113 days of ensiling. Density and the fermentation weight losses of the silages were recorded. Initial density of the silages was considerably increased with increased intensity of shredding (p < 0.01). The initial density (DM basis) of the 4× shredded silages ranged from 177 to 236 kg DM/m³ whereas it was 124–163 kg DM/m³ in non‐shredded silages. The 4× shredded silages had the greatest fermentation weight loss at day 1 of ensiling (p < 0.01). Overall fermentation weight loss after 113 days of ensiling was reduced in the 4× shredded silages (p < 0.01). Shredding increased L‐lactate concentration and reduced pH of the silages (p < 0.01). The NH₃ concentrations were reduced by 25%–46% in 4× shredded silages and butyrate concentrations were reduced by 76%–97% in shredded silages in comparison to non‐shredded silages (p < 0.01). Shredding improved initial density and fermentation quality of silages while reducing overall fermentation weight losses.     

Effect of sward height on the fermentability coefficient and chemical composition of Guinea grass silage

There is a high correlation between sward height and pasture sward structure. Therefore, in tropical grasslands, taking sward height into account has been a much better strategy in rotational stocking management than considering pre‐defined days of growth. Similarly, sward height could be used to determine the moment when tropical grasses present the best ensilability parameters. This study aimed to identify the sward height at which Panicum maximum cv. Mombaça (Guinea grass) provides the highest fermentability coefficient (FC) and to define the combination of additives that best improves the chemical composition of silage. Two trials were carried out in Selvíria, MS, Brazil, from 2015 to 2016. The first year was used to identify the highest FC, and the second year was used to identify the best combination of eight additives (citrus pulp [CIP], homofermentative and heterofermentative LAB, their combinations and control). Statistical analyses were performed using SAS (p < .05), and one contrast was defined as silage with CIP vs. silage without CIP. The height of 130 cm resulted in the highest FC (31.01). Silages inoculated with CIP had better quality than silages without CIP, due to the high crude protein (8.3 vs. 7.3% DM), DM recovery (98.6 vs. 93.3% DM), low pH (3.92 vs. 4.91) and NH₃‐N values (2.49 vs. 14.73% total N). Sward height is a consistent parameter for determining the time of ensiling Guinea grass, and the inclusion of CIP is necessary to raise the silage quality.     

Effects of Lactobacillus buchneri as a silage inoculant and as a probiotic on feed intake,apparent digestibility and ruminal fermentation and microbiology in wethers fed low‐dry‐matter whole‐crop maize silage

Lactobacillus buchneri was investigated as a silage inoculant and as a probiotic on feed intake, apparent digestibility, and ruminal fermentation and microbiology in wethers fed low‐dry‐matter (DM) whole‐crop maize silage. Maize forage (279 g/kg DM) was ensiled without inoculant (untreated) and with L. buchneri CNCM I‐4323 at 1 × 10⁵ cfu/g fresh forage (inoculated). Six cannulated wethers were arranged in a double 3 × 3 Latin square and assigned to one of three diets: (i) untreated maize silage (untreated), (ii) inoculated maize silage (inoculated), and (iii) untreated maize silage with a daily dose of L. buchneri (1 × 10⁷ cfu/g supplied silage) injected directly into the rumen (LB‐probiotic). Wethers fed the inoculated diet had a higher (p = .050) DM intake (1.30% body weight [BW]) than wethers fed untreated and LB‐probiotic diets (1.17% and 1.18% BW respectively). The relative proportion of Ruminococcus flavefaciens (proportion of total estimated rumen bacterial 16S rDNA) in the rumen of wethers fed inoculated and LB‐probiotic diets (both 0.42%) tended (p = .098) to be lower than in the untreated diet (0.83%). Lactobacillus buchneri as a silage inoculant or as a probiotic had little effect on the variables measured in wethers.     

The effects of wilting grass before ensiling on silage intake

Herbage, predominantly perennial ryegrass (Lolium perenne) grown in Northern Ireland, was harvested at four dates from June to October 1996 (H1, H2, H3 and H4). At each harvest approximately one-fifth of the grass harvested was artificially dried and pelleted (G). The remainder of the grass was either wilted for 28–52 h (W), depending on the weather conditions, or ensiled directly, i.e. unwilted (UW). Within the W and UW treatments an inoculant or formic acid additive was applied to the herbage before ensiling. After a minimum ensiling period of 10 weeks, sixty steers, mean initial live weight 432 (s.d. 37) kg, were offered the twenty forages in a four-period partially balanced changeover design experiment. Each period was of 2 weeks’ duration. Dry-matter (DM) intakes were recorded daily, with intakes in the second week of each period used in the statistical analysis of the data. The digestibility of each of the forages was also determined in vivo using four castrated male sheep per silage. Wilting increased the DM content of the silage and the pH, the largest increase in DM content occurring at the second harvest. On average, wilting proportionally increased silage DM intake by 0·21 compared with the unwilted silage (P < 0·001), but the intake of the wilted silage was not significantly different from that of the artificially dried and pelleted grass (P > 0·05). The intake of the wilted silage was higher than that of the unwilted silage at each harvest, the proportional increases being 0·22 (P < 0·001), 0·41 (P < 0·001), 0·19 (P < 0·001) and 0·05 (P > 0·05) at harvests H1, H2, H3 and H4 respectively. Treatment of the grass with formic acid before ensiling resulted in a proportional increase in silage intake of 0·08 compared with the inoculant-treated silage (P < 0·05). Compared with the inoculant-treated silage, formic acid increased silage intake by 0·08, 0·02, 0·14 and 0·10 at harvests H1 (P > 0·05), H2 (P > 0·05), H3 (P < 0·01) and H4 (P < 0·05). The results of this study indicate that the effect of wilting on silage intake varies across different harvests and additive treatments. The difference in response to wilting across different harvests is mainly a result of the prevailing weather conditions during wilting.     

Modelling feed intake and milk yield responses to different grass ley harvesting strategies

A meta‐analysis of feeding trials using grass silages was conducted to predict production responses for dairy cows fed grass silage. They were divided into two subsets: 69 diets from 11 studies were used for comparison of silages made from primary growth and regrowth grass (harvesting subset), and another 157 diets from 24 studies were used for comparison of digestibility influenced by the maturity of grass ensiled (D‐value, digestible organic matter in dry matter) (maturity subset). The minimum prerequisite for an experiment to be included in the data set was that milk production, feed intake, silage characteristics and concentrate ingredients were reported. Both subsets were analysed using the mixed model procedures of SAS. The mean response in dry‐matter intake (DMI) and silage DMI to improved silage D‐value was 0.0175 and 0.0161 kg per unit D‐value (g/kg DM) respectively. The average increase in milk and energy‐corrected milk yield was 0.30 and 0.37 kg per 10‐unit increase in silage D‐value respectively. Milk protein concentration increased, and fat concentration tended to increase with enhanced silage D‐value. Each 10‐unit increase in D‐value reduced milk yield by 0.092 kg at a given dietary metabolizable energy intake (MEI), suggesting that the ME concentration of high D‐value silages was overestimated. Cows fed regrowth silage produced 0.55 kg/day more energy‐corrected milk than those fed primary growth silage at a given dietary MEI. The prediction models can be used to improve ration formulation systems or incorporated into economic models for optimizing milk production in various farming systems.     

Yield,quality and ensilage characteristics of whole‐crop maize and of the cob and stover components: harvest date and hybrid effects

The objective of the study was to determine the effects of maize hybrid and harvest date on the yield, quality and subsequent conservation characteristics of whole‐crop, cob and stover silages. The experiment had a split‐plot design, with three main plots (date of harvest) and six subplots (hybrid) in each of three replicate blocks. Four maize hybrids (Tassilo, Beethoven, Andante and Nescio) were conventional hybrids used in commercial livestock production in Ireland, and two were categorized as high‐biomass hybrids (Atletico and KXA 7211). The three harvest dates – 16 September, 7 October and 28 October – represented early, normal and late harvests respectively. Averaged across hybrids, harvesting on 16 September reduced the DM yield (P < 0·05) and starch concentration (P < 0·01) of whole‐crop and cob, and decreased the neutral detergent fibre (P < 0·05) and acid detergent fibre (P < 0·01) contents of stover. Later harvesting date generally resulted in a more restricted, heterolactic fermentation that was associated with increased dry‐matter (DM) content at ensiling. Whole‐crop and stover from Atletico and KXA 7211 generally had higher DM yields (P < 0·05) and a more extensive fermentation compared to Tassilo, Andante and Nescio. Despite the high‐biomass hybrids having a higher DM yield than conventional hybrids, the high‐biomass hybrids had a lower (P < 0·05) content of cob and a corresponding higher (P < 0·05) content of stover. The changes in proportions of cob and stover in whole‐crop maize with later harvesting significantly influenced its silage digestibility and conservation characteristics.     

Effects of applying Lactobacillus plantarum and Chinese gallnut tannin on the dynamics of protein degradation and proteases activity in alfalfa silage

The effects of Lactobacillus plantarum (LP) and Chinese gallnut (Rhus chinensis Mill) tannin on the fermentation quality, nitrogen distribution, protein fractions and proteases activity of alfalfa (Medicago sativa) silage were studied. Additives added to alfalfa forage (approximately 40% DM) were LP (1 × 10⁶ cfu/g FW) plus sucrose (4 g/kg FW) (LP + S), LP (1 × 10⁶ cfu/g FW) plus commercial cellulase (0.1 g/kg FW) (LP + C) and Chinese gallnut tannin at two levels (20 and 50 g/kg DM) (TA 2% and TA 5%). The control was sprayed with the same volume of distilled water. Silage was sampled and analysed on days 1, 3, 5, 7, 14, 21, 28 and 35. The results showed that the degradation of protein to nonprotein nitrogen took place mainly during the first 3 days, while the degradation of peptides and free amino acids occurred throughout the ensiling process. All additives lowered nonprotein nitrogen and free amino acids nitrogen proportion during the ensiling. Additive TA 5% was the most effective to inhibit proteolysis among the four additives, followed by LP + S. They inhibited the activities of all three plant proteases and decreased production of nonprotein nitrogen, free amino acids and ammonia nitrogen during the ensiling process.     

Effects of applying a bacterial inoculant to silage immediately before feeding on silage intake, digestibility, degradability and rumen volatile fatty acid concentrations in growing beef cattle

In an experiment, involving twelve male cattle (initially 235 kg live weight), the effects of applying lactic acid bacteria [Lactobacillus plantarum; 10⁹ colony-forming units (g fresh silage)^?1] to grass silage, immediately prior to that silage being fed, on dry-matter (DM) intake of the silage, degradability of nitrogen (N) and fibre in the rumen, total tract digestibility and composition of rumen fluid in the animals were examined. A grass silage, which had been made from the primary growth of a predominantly perennial ryegrass sward, was offered as the sole diet. The inoculant was applied to the silage at the rate of 2 g of freeze-dried powder reconstituted in 12 ml of water (kg fresh silage)^?1 immediately prior to that silage being fed and an equivalent amount of water was applied to the silage in the control treatment. The two diets were compared in a change-over design. The silage was well preserved, having a pH and concentrations of ammonia N and butyrate of 3.72, 74 g (kg total N)^?1 and 0.11 g (kg DM)^?1 respectively. Application of the inoculant significantly increased true protein, acid-insoluble N and water-soluble carbohydrate concentrations (P < 0.001) in the diet. Silage DM intake was not significantly increased (P= 0.072) by this of inoculant treatment, which had no significant effect (P > 0.05) on rumen degradability or total tract digestibility of DM, N, neutral detergent fibre or modified acid detergent fibre. Rumen pH, ammonia concentration or the molar proportions of volatile fatty acids were not altered (P>0.05) by inoculant treatment. It is concluded that application of the inoculant to the silage prior to silage being fed did not significantly affect silage DM intake, total tract digestibility, or degradability or fermentation in the rumen of cattle offered grass silage as the sole diet. It is also concluded that the results of this experiment provide no evidence that the mode of action of L plantarum, applied as an additive to grass at ensiling in previous studies, is through ‘direct’ effects in the rumen.     

Effect of forage species and ensiling conditions on silage composition and quality and the feed choice behaviour of goats

The hypothesis was that forage species and ensiling conditions have an impact on the formation of biogenic amines and the feed choice of goats in short‐term preference trials. At ensiling, lucerne (Medicago sativa L., first cut), red clover (Trifolium pratense L., first cut) and Italian ryegrass (Lolium multiflorum Lam ., second cut) were treated differently to obtain a range of fermentation qualities. Six treatments of each forage species were prepared and included different dry‐matter concentrations, chemical and biological silage additives, and additions of soil. Silages were sampled for chemical analyses (proximate constituents, fermentation products and other volatile compounds, crude protein fractions and biogenic amines) and stored anaerobically in vacuum‐sealed plastic bags for use in preference trials (one trial for each forage species) with Saanen‐type wethers (n = 8 or 6). Each possible two‐way combination of the six silage treatments and a standard hay (n = 21 combinations) was offered for ad libitum intake for 3 hr. Data were analysed using multidimensional scaling, analysis of variance and correlation analysis between silage characteristics and dry‐matter intake (DMI). For each forage species, fermentation characteristics and crude protein fractions revealed only small differences among treatments. Although the degree of proteolysis, as measured by non‐protein nitrogen, of all silages was high, biogenic amine and butyric acid concentrations were low. The different treatments apparently had no direct influence on the formation of biogenic amines and feed choice. The preference behaviour within one forage species was strongly divergent, but DMI rankings of the three species were very similar.     

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.     

Effect of tannin extracts on protein degradation during ensiling of ryegrass or lucerne

Eleven laboratory‐scale trials were undertaken in different years where ryegrass (Lolium perenne L.) or lucerne (Medicago sativa L.) were ensiled with different concentrations of tannin extracts (quebracho, Schinopsis balansae Engl., mimosa, Acacia mearnsii DE WILD.), and the effects on protein degradation were assessed. The dry‐matter (DM) content in grass silages ranged between 186 and 469 g/kg and in lucerne silages between 187 and 503 g/kg. Tannin extract, either quebracho or mimosa, was applied at 0–30 g/kg forage DM. Commercial additives such as Lactobacillus plantarum, formic acid or hexamine + NaNO₂ were applied in two of the grass trials and in six of the lucerne trials. Eight of the trials incorporated a maximum ensiling duration of 90 or 180 days in addition to replicates which were opened and evaluated at earlier stages. All trials included silages which were assessed after at least 49 days of anaerobic storage. The crude protein (CP) fraction A (non‐protein nitrogen, NPN) as proportion of total CP, served as the main indicator for proteolysis. In ryegrass, in general, the level of proteolysis was lower than in lucerne. A correlation of DM content in silages and degree of proteolysis was only evident for ryegrass. In both forages, the degradation of true protein slowed considerably after 24 days of ensiling. True protein was conserved most with the highest level of tannin extract addition. However, in lucerne, the combination of formate with lactobacilli was equally effective up to 330 g DM/kg, and deamination was further inhibited by formic acid compared to tannin extracts.