The effects of stage of growth and additives with or without cellulase on fermentation and in vitro degradation characteristics of Leymus chinensis silage

This study evaluated the effects of different combinations of added lactic acid bacteria and cellulase applied at two growth stages on chemical composition and in vitro rumen digestibility of Leymus chinensis silage. Fresh grass was harvested at early heading stage (S1) and late heading stage (S2), respectively, and ensiled with five additives: 200 U cellulase (C) kg^?1 fresh matter (FM), 1 × 10⁵ colony‐forming units (cfu) Lactobacillus plantarum (LP) g^?1 FM, 1 × 10⁵ cfu Lb. casei (LC) g^?1 FM, LP+C, LC+C and a control (CK). Four replicates of each treatment were weighed into 5‐L plastic buckets, and the mini silos were stored at ambient temperature (~30°C) for 60 d. Leymus chinensis harvested at S2 showed relatively higher neutral detergent fibre content, coliform bacteria count and lower crude protein content than S1. All additives decreased the pH and ammonia nitrogen (NH₃‐N) content of L. chinensis silage (P < 0·001) except C. LP+C and LC+C decreased fibre content and increased water‐soluble carbohydrate content (P < 0·001). The silages were further anaerobically incubated in vitro at 39°C for 48 h with buffered rumen fluids of lactating cows. Leymus chinensis harvested at S2 showed lower in vitro dry‐matter disappearance, NH₃‐N, total volatile fatty acid (VFA) content and higher average gas production rate (P < 0·05) than S1. In conclusion, Leymus chinensis should not be harvested too late. Compared with other treatments, a combination of Lb. casei (LC) with cellulase resulted in better fermented silage, but further testing is needed to confirm its efficacy.     

Effects of potassium sorbate and sodium benzoate at two application rates on fermentation and aerobic stability of maize silage

This study evaluated two potassium sorbate (PS) and sodium benzoate (SB) application rates in improving the aerobic stability of maize silage. Treatments included no additive, the addition of PS at 1 and 2 g kg^?1 fresh matter (FM) and the addition of SB at 1 and 2 g kg^?1 FM. Four replicates of each treatment were ensiled in 15‐L plastic jars. The silages were analysed for their fermentative characteristics and were subjected to an aerobic stability test with pH and yeast and mould count measurements. Considering fermentation quality and aerobic stability, both additives were effective. The PS was more active against yeasts during aerobic exposure. When the additives were applied at 2 g kg^?1, the silages were more stable (256 h, on average) than those with 1 g kg^?1 (119 h, on average) and control (61 h). Aerobic deterioration was more pronounced in the controls than in the treated silages. Silages treated at 2 g kg^?1 had consistent effects on pH values and yeast counts over 288 h of aerobiosis. Overall, PS and SB applied at 2 g kg^?1 were more effective in improving aerobic stability.     

Effects of additives on the fermentation and aerobic stability of grass silages and total mixed rations

Mown herbage of timothy–meadow fescue (dry matter 218 (LDM) or 539 (HDM) g kg^?1) was ensiled in laboratory silos to evaluate silage additives. For LDM silage, additives including formic acid (a blend of formic acid, sodium formate, propionic acid, benzoic acid, glycerol and another blend of formic acid and ammonium formate, both applied at 5 L t^?1) were able to restrict fermentation and thereby improve intake potential of the silage. Aerobic stability (AS) of total mixed ration (TMR) was also improved. LDM grass treated with homofermentative lactic acid bacteria (_hoLAB) resulted in silage containing lactic acid at 132 g kg^?1 DM, ammonium‐N <40 g kg^?1 total N, and pH < 3·8, and the AS was poor (<36 h). The treatment including heterofermentative strain (Lactobacillus brevis) produced more acetic acid and better AS than _hoLAB. Salt treatment (sodium benzoate, potassium sorbate, sodium nitrite) reduced pH compared to the Control treatment (3·89 vs. 4·24) and improved AS of TMR. The LDM Control silage had good AS, but the TMR based on it had poor AS. All additives were able to lower pH on HDM silages also, but other benefits of using additives were minimal. The treatment including L. brevis on HDM was able to improve AS of TMR.     

Lactic acid bacteria strains for enhancing the fermentation quality and aerobic stability of Leymus chinensis silage

Leymus chinensis is an important grass in China and Russia. Six lactic acid bacteria (LAB) strains (LB, LPL1, LPL2, LPL3, LCL and WH) from L. chinensis silage were screened and identified and their effects on fermentation quality were investigated. All six strains were grown at 6·5% NaCl and pH 4·00. Strains LPL1, LPL2 and LPL3 were identified as Lactobacillus plantarum, and LB, WH and LCL were classified as Lactobacillus brevis, Weissella hellenica and Lactobacillus casei respectively. The six isolated strains and a commercial inoculant (Lactobacillus buchneri) were added to L. chinensis for ensiling at densities of 500 and 600 kg m^?3. The control was sprayed with the same volume of distilled water. The effects of the strains on fermentation quality after 45 d ensiling and aerobic stability during 8 d of exposure to air were evaluated. The 600 kg m^?3 silage had lower pH, butyric acid, ammonia nitrogen content and coliform bacteria counts than the 500 kg m^?3 density silage (P < 0·05). The six isolated strains decreased pH, butyric acid content and increased lactic acid content, and all inoculants increased L. chinensis silage aerobic stability except LCL (P < 0·05). The fermentation quality of L. chinensis silage increased with higher ensiling density. The LAB strains improved the fermentation quality, and high‐quality silage could be obtained at low ensiling density with the addition of the LAB strains. The strains improved the aerobic stability; Lb. buchneri and Lb. brevis showed the best performance.     

Silage quality and preservation of Urtica cannabina ensiled alone and with additive treatment

Urtica cannabina (U. cannabina), a member of the Urticaceae family, is widely distributed throughout the temperate regions of the world and can be used as a nutritious feed for animals through the winter period. To provide high‐quality forage all year‐round, we treated freshly harvested U. cannabina without additives (control), but with corn flour (CF) (5:1 w/w), molasses (2, 4, and 8% fresh weight), or LalsiL Dry (LD) inoculant (5, 10 and 20 mg kg^?1 of fresh weight). We then assessed the chemical composition, in vitro digestibility and fermentative parameters of the products after 0, 3, 5, 15, 20 and 60 d of ensiling. The results showed that: (i) U. cannabina had large quantities of protein and some essential minerals, including calcium, potassium, sodium, zinc, copper and manganese, and was particularly rich in magnesium and iron. (ii) U. cannabina can be preserved as a highly nutritious silage. No additive treatment or the LD inoculant treatments produced badly preserved silages. The 2% molasses treatment produced badly preserved silage, but 4–8% molasses produced well‐preserved silages. The CF treatment also produced well‐preserved silage. We recommend the application rates of molasses at 4–8% of fresh weight or 5:1 CF to improve U. cannabina silage.     

Methylotrophic yeast,lactic acid bacteria and glycerine as additives for sugarcane silage

The ensiling of sugarcane results in high dry‐matter (DM) loss, but the addition of glycerine may compensate for the loss during ensiling. Methanol is the most undesirable contaminant of crude glycerine destined for animal feeding. The aim of this study was to evaluate the ability of the yeast strain Pichia methanolica NCYC 1381 to reduce the methanol concentration in sugarcane silage inoculated with Lactobacillus hilgardii CCMA 0170 + glycerine. A randomized design consisted of four dose rates of glycerine (0, 4, 8 and 12% of fresh forage), three periods of silage fermentation (11, 34 and 68 d) and three combinations of microbial additives [L. hilgardii (LH), L. hilgardii plus P. methanolica (LH + PM) and without microbial additive (WI)]. The DM of the fresh sugarcane was 275 g kg^?1. The linear reduction in neutral detergent fibre caused by glycerine inclusion was probably due to a dilution effect. The LH treatment increased the concentrations of the succinic, acetic and propionic acids, and 1,2‐propanediol, and reduced the yeast population. The LH + PM treatment increased DM loss of sugarcane silage with 12% glycerine and L. hilgardii CCMA 0170 (6·1 log cfu g^?1 of FM) reduced the DM loss when compared to the silage without additives. Under the conditions of the experiment, the P. methanolica treatment did not reduce the methanol concentration in silage.     

Validation of the Rostock fermentation test as an in vitro method to estimate ensilability of forages using glass jar model silages as a basis for comparison

This study compared the predictive power of an in vitro fermentation test [Rostock fermentation test (RFT)] with common glass jar silages (GLASS) using maize, fresh and wilted perennial ryegrass and fresh and wilted lucerne. Treatments were made in quadruplicate and included a control variant without additives, sucrose (20 g kg^?1), a homolactic inoculant (Lactobacillus plantarum, 3 × 10⁵ cfu g^?1), a heterolactic inoculant (Lactobacillus buchneri, 1 × 10⁵ cfu g^?1) and combinations of each inoculant with sucrose. The pH was measured in GLASS at days 1·5, 3, 10 and 90, and in RFT at 14, 18, 22, 26, 38 and 46 h, whereas fermentation products were determined at days 3 and 90 in GLASS, and at 46 h in RFT. Linear regressions revealed the closest relation for pH between 10‐d silages of GLASS and 38‐h measurement of RFT (adjusted R² = 0·808) and coefficients of determination for fermentation products were always higher when 3‐d instead of 90‐d silages were compared with 46‐h measurement of RFT. A pH increase in GLASS as indicator of insufficient anaerobic stability was not reproduced by RFT, suggesting that the in vitro test reflects the initial phase of fermentation, which was also indicated by the absence of 1,2‐propanediol in RFT.     

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

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

Effect of grazing management on herbage protein concentration,milk production and nitrogen excretion of dairy cows in mid‐lactation

The objective of this experiment was to use diurnal and temporal changes in herbage composition to create two pasture diets with contrasting ratios of water‐soluble carbohydrate (WSC) and crude protein (CP) and compare milk production and nitrogen‐use efficiency (NUE) of dairy cows. A grazing experiment using thirty‐six mid‐lactation Friesian x Jersey cows was conducted in late spring in Canterbury, New Zealand. Cows were offered mixed perennial ryegrass and white clover pastures either in the morning after a short 19‐day regrowth interval (SR AM) or in the afternoon after a long 35‐day regrowth interval (LR PM). Pasture treatments resulted in lower pasture mass and greater herbage CP concentration (187 vs. 171 g kg^?1 DM) in the SR AM compared with the LR PM but did not affect WSC (169 g kg^?1 DM) or the ratio of WSC/CP (1·0 g g^?1). Cows had similar apparent DM (17·5 kg DM cow^?1 d^?1) and N (501 g N cow^?1 d^?1) intake for both treatments. Compared with SR AM cows, LR PM cows had lower milk (18·5 vs. 21·2 kg cow^?1 d^?1), milk protein (0·69 vs. 0·81 kg cow^?1 d^?1) and milk solids (1·72 and 1·89 kg cow^?1 d^?1) yield. Urinary N concentration was increased in SR AM, but estimated N excretion and NUE for milk were similar for both treatments. Further studies are required to determine the effect of feeding times on diurnal variation in urine volume and N concentration under grazing to predict urination events with highest leaching risk.     

Animal and forage responses on Maximus,a tetraploid cultivar vs Marshall,a diploid cultivar of annual ryegrass

This 2‐year grazing study carried out at Raymond, Mississippi, USA, evaluated animal performance and forage characteristics of a tetraploid (“Maximus”) vs a diploid cultivar (“Marshall”) of annual ryegrass at three stocking rates (SR; 3.5, 5.0 or 7.5 animals per ha). Angus cross‐bred heifers (Bos taurus; initial body weight [BW] = 240 kg) were continuously stocked on pastures at set stocking rates for the duration of the study. Stocking rates and cultivars were arranged in a 3 × 2 factorial design that was completely randomized with two replications. There was no cultivar effect (p = .449) on average annual herbage mass (HM). However, HM decreased linearly with increasing SR (p = .001) from 3.8 to 2.5 t ha^?1 during Year 1 and 4.4 to 3.8 t ha^?1 during Year 2 (p = .028). In Year 2, there was a difference in water‐soluble carbohydrates (WSC) between cultivars (p = .012; Marshall, 117.0 vs Maximus, 139.0 g/kg). There was no cultivar effect (p > .10) on average daily gain (ADG) in either year of the study. In both years, ADG decreased linearly with increasing SR (p = .001) from 1.22 to 0.98 kg/d during Year 1 and 1.31 to 1.08 kg/d during Year 2. Across years, gain ha^?1 increased linearly (p < .001) with increasing SR. Our results showed no difference in animal performance and HM between the two cultivars. Producers’ choice of annual ryegrass cultivar should be based on seeding cost and agronomic traits that allow for better adaptation of the forage.     

Effects of replacing timothy silage by alsike clover silage on performance,carcass traits and meat quality of finishing Aberdeen Angus and Nordic Red bulls

The objective of the study was to determine the effects of silage plant species and cattle breed on performance and meat quality of finishing bulls. A feeding experiment was conducted using thirty Aberdeen Angus (AA) and thirty Nordic Red (NR) bulls. Both breeds were randomly allotted to three experimental diets. The composition (g kg^?1 dry matter) of the diets was as follows: (i) timothy silage (TS) (650) and barley (350); (ii) TS (325), alsike clover silage (AS) (325) and barley (350); and (iii) AS (650) and barley (350). The bulls were fed a total mixed ration ad libitum. Replacing TS by AS did not affect dry‐matter intake, growth, carcass conformation or meat quality traits of the bulls, but carcass fat score tended to decrease when replacing TS by AS (P = 0·07). The AA bulls grew faster and had better feed conversion and superior carcass conformation compared with the NR bulls (P < 0·001). The loin of the AA bulls had lower shear force value and was given higher scores in sensory analyses compared with the NR bulls (P < 0·01). The experiment demonstrated that replacing TS by AS in the diet of finishing bulls had minor effects on performance or meat quality.     

Potential of Cistus ladanifer L. (rockrose) in small ruminant diets – effect of season and plant age on chemical composition,in vitro digestibility and antioxidant activity

Shrubs can provide an important contribution to the fodder resources for small ruminants in Mediterranean areas, but there is limited information on their feed value, including secondary metabolites and their seasonal differences. This study evaluated the effect of seasonal variation in chemical composition, in vitro digestibility and antioxidant activity of the aerial parts of plants of Cistus ladanifer of two age groups [young plants vs. older ones (2–6 years old)]. Aerial parts of C. ladanifer plants of both age groups were characterized by moderate cell‐wall content [321–410 g NDF kg^?1 dry matter (DM)], high levels of phenolic compounds (55·1–106 g gallic acid equivalents per kg DM) and condensed tannins (CT) (32·1–161 g kg^?1 DM), low protein content (55–100 g kg^?1 DM) and low digestibility (249–315 g of digestible organic matter per kg DM). During autumn and winter, C. ladanifer showed higher protein levels and lower cell‐wall content than in the other seasons. The highest values of phenolic compounds, CT and antioxidant activity were achieved during summer. Young plants showed higher levels of phenolic compounds during spring, summer and winter, and higher CT contents in summer (more than 54 g kg^?1 DM) compared to old plants. Aerial parts of C. ladanifer of both age groups may be used as a component of ruminant nutrition, but only as a supplement and associated with other feeding resources to complement its nutritional imbalances.     

Herbage dry‐matter production and forage quality of three legumes and four non‐leguminous forbs grown in single‐species stands

Agronomic data on most broad‐leaved species of grasslands are scarce. The aim of this study was to obtain novel information on herbage DM yield and forage quality for several forb species, and on species differences and seasonal patterns across harvests and in successive years. Four non‐leguminous forbs [salad burnet (Sanguisorba minor), caraway (Carum carvi), chicory (Cichorium intybus) and ribwort plantain (Plantago lanceolata)] and three leguminous forbs [yellow sweet clover (Melilotus officinalis), lucerne (Medicago sativa) and birdsfoot trefoil (Lotus corniculatus)] and a perennial ryegrass–white clover mixture were investigated in a small‐plot cutting trial in Denmark during 2009 and 2010. Plots were harvested four times per year. On average, annual herbage yield was highest for lucerne (15·4 t DM) and grass–white clover (12·5 t DM ha^?1), and lowest for salad burnet (4·6 t DM ha^?1) and yellow sweet clover (3·9 t DM ha^?1). Ribwort plantain and lucerne had the highest concentrations of acid detergent fibre (339 and 321 g kg^?1 DM respectively) and lignin (78 and 67 g kg^?1 DM respectively); contents in other species were similar to grass–white clover (275 and 49 g kg^?1 DM respectively). No common feature was found within the functional groups of non‐leguminous forbs and leguminous forbs, other than higher crude protein contents (198–206 g kg^?1 DM) in the legumes. DM yield and fibre content were lowest in October. Digestibility declined with higher temperature and increasing fibre content. Results are discussed in terms of the potential of forbs to contribute to forage resources in farming practice.     

Volatile fatty acid proportions and microbial protein synthesis in the rumen of cattle receiving grass silage ensiled with different rates of formic acid

Timothy–meadow fescue herbage was ensiled with formic acid (FA) (expressed as 100% solution) at the rates of 0, 2, 4 or 6 L t^?1. The silages were fed along with concentrates to bulls fitted with cannulae in the rumen and duodenum. The ration comprised grass silage (700 g kg^?1), barley (240 g kg^?1) and rapeseed meal (60 g kg^?1). The application rate of FA had no effect on the site or extent of the digestion of dietary organic matter (OM) and neutral‐detergent fibre. The flow of total N at the duodenum increased linearly (P < 0·05) with application rate of FA, reflecting mainly an increased (P < 0·01) flow of microbial N. The apparent efficiency of net microbial protein synthesis in the rumen increased (P < 0·05), the proportion of propionate in the volatile fatty acids (VFA) in the rumen was not affected (P > 0·05) but that of butyrate increased (linear and quadratic effects, P < 0·01) with increasing rate of FA. It is concluded that an increase in the rate of FA at ensiling leads to a higher utilization of energy and/or protein‐yielding substrates for rumen microbes and to a modified rumen VFA pattern with an increased proportion of butyrate.     

Nitrogen metabolism and milk production in dairy cows fed semi‐restricted amounts of ryegrass–legume silage with birdsfoot trefoil (Lotus corniculatus L.) or white clover (Trifolium repens L.)

In change‐over trials, mid‐lactation dairy cows were fed concentrate‐supplemented, isonitrogenous and isofibrous perennial ryegrass–legume silage diets that satisfied energy requirements but were suboptimal with respect to metabolizable protein supply. Legumes were either birdsfoot trefoil with low levels of condensed tannins (typical for hemiboreal conditions), or white clover. Averaged over two experimental years, birdsfoot trefoil–based silage resulted in lower digestibility (P < 0·001) of dry matter (50 g kg^?1), organic matter (52 g kg^?1), neutral detergent fibre (120 g kg^?1) and nitrogen (24 g kg^?1) and lower rumen total volatile fatty acid concentration (7 mm ; P = 0·009). Milk protein yield was 36 g d^?1 higher with birdsfoot trefoil silage (P = 0·002), while raw milk yield tended to be 0·8 kg d^?1 higher (P = 0·06). Rumen ammonia concentration was similar between diets, but milk urea concentration (P < 0·001), urinary urea excretion (P = 0·002) and faecal‐N proportion (P = 0·001) were higher with birdsfoot trefoil silage. The results suggest that grass–birdsfoot trefoil silage produced in hemiboreal areas exhibits a protein‐sparing effect in dairy rations, despite a low condensed tannin content that is further diluted by companion grasses and ration concentrate proportion.     

Differences in the crude protein fractions of lucerne leaves and stems under different stand structures

Protein degradability in forage legumes is of global importance because utilization efficiency of forage has economic and environmental consequences. However, there are no published studies on the effect of legume stand structure on differences in crude protein (CP) fractions. The main objective of the present research was therefore to investigate differences in CP fractions in leaves and stems of lucerne (Medicago sativa L.) during the growing season. Stand traits were measured over 2 years, and forage was sampled at the early bud and early flower stages in the first, second and third cuts. Stems had significantly higher concentrations (in g kg^?1 CP) of non‐protein (fraction A: 430 g kg^?1 CP) and indigestible nitrogen (fraction C: 92 g kg^?1 CP) than leaves and had lower relative content of true protein (fraction B: 478 g kg^?1 CP). In the total forage (stems and leaves combined), about 80% of the variation in CP fractions was explained by year, cut and maturity. Year was the most important factor, particularly for the B fractions. Cut was the second‐most important factor; its main effect was that the relative abundance of fraction A declined from 394 g kg^?1 CP in the first cut to 293 in g kg^?1 CP the third cut. Maturity increased the amounts of indigestible fraction C and protein fractions B₁ and B₃. This was associated with the leaf weight ratio, which had an inverse relationship with maximal stem length and dry matter yield. Variation partitioning showed that 75% of CP fraction variability associated with cut, maturity and year could be explained by the evaluated stand traits. This research has highlighted the need to consider plant morphological traits when legume CP fractions are evaluated.     

Effect of ensiling field bean, field pea and common vetch in different proportions with whole-crop wheat using formic acid or an inoculant on fermentation characteristics

Whole‐crop field bean (FB), field pea (FP) and common vetch (CV) [155, 213 and 238 g dry matter (DM) kg^?1] were ensiled in 1·5 L laboratory silos with whole‐crop wheat as mixtures of 0, 0·25, 0·50, 0·75 and 1·00 of fresh weight (FW). Silages were ensiled (i) without additive, and (ii) with formic acid (FA) (4 L t^?1) or (iii) an inoculant (Lactobacillus plantarum, 10⁶ colony‐forming units g^?1 FW) as additives. The concentrations of water‐soluble carbohydrates in herbage of whole‐crop FB, FP, CV and wheat were 93, 157, 67 and 114 g kg^?1 DM and the buffering capacities were 588, 710, 755 and 429 mEq kg^?1 DM respectively. Field bean and FP silages were mainly well preserved with low pH values and moderate fermentation losses, except for FB‐only silage without additive which had a high butyric acid concentration. Common vetch silages had higher pH values and were less well fermented compared to the silages of the other legumes. For all legumes, FA reduced ammonia‐N concentrations more effectively compared to other additive treatments. In conclusion, in FB and FP silages the use of FA or an inoculant, as additives, ensured good preservation up to a proportion of legume in the herbage of 0·75. With all legume silages, and with those containing CV, only FA, as an additive, adequately restricted protein breakdown.     

Determining the critical plant test potassium concentration for annual and Italian ryegrass on dairy pastures in south‐western Australia

Potassium fertilization in intensive grassland systems is particularly important on sandy soils with limited K storage capacity. A 3‐year plot experiment was conducted in south‐western Australia to determine the critical K concentration in herbage dry matter (DM) of annual and Italian ryegrass required to achieve 0.95 of the maximum yield, under best‐practice grassland management. A factorial design was employed with eight fertilizer K rates (range 0–360 kg ha^?1 year^?1) and two ryegrass species replicated four times, on a sandy soil site managed over 7 years to deplete mean soil Colwell K concentration to 42 mg/kg. Herbage was defoliated six times per year at the 3‐leaf stage of regrowth. Herbage DM yield, macronutrient and micronutrient concentrations were measured at each defoliation. Dry‐matter yield increased significantly (p < .001) with increasing levels of K fertilizer in all 3 years and the effect was curvilinear, while 0.95 of the maximum herbage DM yield was achieved at an annual K fertilizer application rate of 96, 96 and 79 kg/ha respectively. At these K fertilizer application levels, the mean K concentration of herbage DM over the 3 years was derived to be 11.4, 12.7 and 11.2 g/kg respectively. Sodium, magnesium and calcium concentrations of herbage DM all declined significantly (p < .001) as the K concentration increased. Grassland producers on sandy soils should target a K concentration in herbage DM of 16 g/kg for annual ryegrass and Italian ryegrass‐dominant swards to ensure K availability is not limiting herbage production.     

The effects of defoliating grass in winter or spring on herbage yields and ensilage characteristics

Under Irish conditions, the digestibility in May of grass managed for silage production is sometimes lower than expected. In each of two successive years, replicate field plots were established to examine the effects of three defoliation heights (uncut or cut to a stubble height of 10 or 5 cm) applied in winter and/or spring on herbage yields harvested in May and again in July, and on chemical composition and conservation characteristics associated with first‐cut silage. Swards that were not defoliated in December or March had a dry‐matter (DM) yield and in vitro DM digestibility (DMD) in mid‐May of 6597 kg ha^?1 and 736 g kg^?1, respectively, in Year 1, and corresponding values of 7338 kg ha^?1 and 771 g kg^?1 in Year 2. Defoliating swards to 5 cm in December reduced (P < 0·001) May DM yields compared to swards that were not defoliated in both December and March, while herbage DMD in May increased (P < 0·001) when defoliated in December or March. There were no clear effects of defoliation height or its timing on herbage ensilability or resultant conservation efficiency characteristics. The effects of defoliation on July yield were the reverse of those observed for May, while the total yield of the December and March defoliations plus the two silage harvests increased as defoliation height was lowered in Year 2 only. It is concluded that defoliation in winter and/or spring can increase herbage digestibility but will likely reduce DM yields in May.     

A meta‐analysis comparing standard polyethylene and oxygen barrier film in terms of losses during storage and aerobic stability of silage

A meta‐analysis was undertaken of 51 comparisons of standard polyethylene film with oxygen barrier (OB) film in covering systems for bunker silos, unwalled clamp silos and bales. Mean losses of DM or OM during storage from the top 10 to 60 cm of bunker and clamp silos were 195 g kg^?1 for standard film and 114 g kg^?1 for OB film systems (41 sets of data, P < 0·001), while mean total losses of DM from baled silage were 76·8 g kg^?1 for standard film and 45·6 g kg^?1 for OB film systems (10 sets of data, P < 0·001). Top surface silage judged subjectively to be inedible was 107 and 29·6 g kg^?1 for standard film and OB film systems respectively (5 sets of data, P = 0·02). Aerobic stability was 75 h for silage stored under standard film system and 135 h for silage stored under OB film system (11 sets of data, P = 0·001). It is concluded that the OB film system reduces losses from the outer layers of silos and from bales and increases the aerobic stability of silage in the outer layers of silos.