Search

SUMMARYPerennial ryegrass evaluation schemes categorize varieties into three maturity (early, intermediate and late) and two ploidy (diploid and tetraploid) groups, and compare the relative yield, persistence and nutritive quality of varieties within these groups. The present study compared these groups for herbage yield, dry matter (DM) concentration and, using near infrared reflectance spectroscopy (NIRS), four quality characteristics (in vitrocontent of digestible dry matter (CDDM), water-soluble carbohydrate (WSC) and crude protein (CP) concentrations, and buffering capacity). A total of 1208 plots were sown across 5 years in Irish Recommended List trials and then harvested 6–7 times in each of 2 harvest years. This also allowed an assessment of the effect of sward age. Maturity group had no significant effect on annual herbage yield, quality or DM concentration except forin vitroCDDM (Pin vitroCDDM (PP<0·01) and buffering capacity (P<0·05) at the first silage harvest. Tetraploid swards had greater annual herbage yields (P<0·001),in vitroCDDM values (P<0·001) and WSC concentrations (P<0·01), but lower CP and DM concentrations (P<0·001) than diploids. Swards in their first full year produced an additional 5·17 t/ha DM (P<0·001) and had a higher (P<0·01) WSC concentration at the second silage harvest than in their second year, but did not differ significantly forin vitroCDDM and WSC, CP or DM concentrations. The present study showed that differences exist in yield, nutritive quality and ensilability indices between maturity and ploidy groups. These observations justify their assessment in variety comparative trials and facilitates particular groups being selected for individual farming systems to increase efficiency.

The selection and feeding of perennial ryegrass (Lolium perenne L.) varieties (PRV) or perennial grass species (PGS) may affect enteric methane (CH4) output because of changes in the fermentation dynamics in the rumen as a result of differences in herbage chemical composition. The objective of this study was to determine the effects of PRV and PGS harvested throughout the growing season on herbage chemical composition, and in vitro rumen fermentation variables and CH4 output per unit of feed using a batch culture technique. Seven PRV (Experiment 1: Alto, Arrow, Bealey, Dunluce, Greengold, Malone, Tyrella) and six perennial grasses [Experiment 2: perennial ryegrass (Navan), perennial ryegrass (Portstewart), cocksfoot, meadow fescue, tall fescue, timothy; defined as PGS], managed under a simulated grazing regime, were incubated for 24 h with buffered rumen fluid in two separate experiments. The CH4 output per unit of feed dry-matter (DM) incubated was not affected (P >0 AE05) by PRV (range of mean values across PRV of 23AE9–25AE3 (SEM 0AE41) mL g )1 DM) or by PGS (25AE6–26AE6 (SEM 0AE37) mL g )1 DM). The CH4 output per unit feed DM disappearing during the in vitro rumen incubation was not affected by PRV (33AE9–35AE1 (SEM 0AE70) mL g )1 DM), and although there was an overall PGS effect (P

Increasing the residual water-soluble carbohydrate (WSC) concentration in silage may improve the nutritional value but impair aerobic stability. Our aim was to determine whether the residual WSC concentration and aerobic stability of low dry-matter (

The Grange Feed Costing Model was modified to simulate the economic implications of grassland management strategies for a grass-based suckler beef calf-to-weanling system at the whole-farm level. The modified model enabled costing of annual grass consumed as grazed grass and silage when the farm grazing and conservation areas are integrated. Grass growth data from sites in the south, east and north of Ireland were used. Sixty-three scenarios were simulated, enabling analysis of site, stocking rate and silage strategy effects on total annual feed cost for the grass forage production system. Total annual feed cost (of grazed grass and grass silage) ranged from €96 to €111 per 1000 UFL (Unite Fourragere Lait) and €411 to €456 per beef cow unit (CU). The silage strategy with respect to the number of harvests and whether the silage area was grazed in the spring had negligible impact on annual total feed cost per CU. However, a tendency towards reduced annual feed cost under a two harvest, relative to a one harvest, silage strategy was observed. The lowest cost stocking rate was 2 CU ha−1. Site-specific differences such as seasonal growth distribution and nitrogen fertilizer response rate had the greatest influence on the annual cost of the grass-based feeding system.

SUMMARYAn agro-economic simulation model was developed to facilitate comparison of the impact of management, market and biological factors on the cost of providing ruminant livestock with feed grown on the farm (home produced feed). Unpredictable year-to-year variation in crop yields and input prices were identified as quantifiable measures of risk affecting feed cost. Stochastic analysis was used to study the impact of yield and input price risk on the variability of feed cost for eight feeds grown in Ireland over a 10-year period. Intensively grazed perennial ryegrass was found to be the lowest cost feed in the current analysis (mean cost €74/1000 Unité Fourragère Viande (UFV)). Yield risk was identified as the greatest single factor affecting feed cost variability. At mean prices and yields, purchased rolled barley was found to be 3% less costly than home-produced spring-sown barley. However, home-produced spring barley was marginally less risky than purchased barley (coefficient of variation (CV) 0·063 v. 0·064). Feed crops incurring the greatest proportion of fixed costs and area-dependent variable costs, including bunker grass silage, were the most sensitive to yield fluctuations. The most energy input-intensive feed crops, such as grass silage, both baled and bunker ensiled, were deemed most susceptible to input price fluctuations. Maize silage was the most risky feed crop (CV 0·195), with potential to be both the cheapest and the most expensive conserved feed.

The potential variance in feedstock costs can have significant implications for the cost of a biofuel and the financial viability of a biofuel facility. This paper employs the Grange Feed Costing Model to assess the cost of on-farm biomethane production using grass silages produced under a range of management scenarios. These costs were compared with the cost of wheat grain and sugarbeet roots for ethanol production at an industrial scale. Of the three feedstocks examined, grass silage represents the cheapest feedstock per GJ of biofuel produced. At a production cost of €27/tonne (t) feedstock (or €150/t volatile solids (VS)), the feedstock production cost of grass silage per gigajoule (GJ) of biofuel (€12.27) is lower than that of sugarbeet (€16.82) and wheat grain (€18.61). Grass biomethane is also the cheapest biofuel when grass silage is costed at the bottom quartile purchase price of silage of €19/t (€93/t VS). However, when considering the production costs (full-costing) of the three feedstocks, the total cost of grass biomethane (€32.37/GJ of biofuel; intensive 2-cut system) from a small on-farm facility ranks between that of sugarbeet (€29.62) and wheat grain ethanol (€34.31) produced in large industrial facilities. The feedstock costs for the above three biofuels represent 0.38, 0.57, and 0.54 of the total biofuel cost. The importance of feedstock cost on biofuel cost is further highlighted by the 0.43 increase in the cost of biomethane when grass silage is priced at the top quartile (€46/t or €232/t VS) compared to the bottom quartile purchase price. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd

a b s t r a c t This study evaluated concentrations of archaeol, a lipid biomarker for Archaea and, presum- ably, methanogens in cattle faeces. Twelve continental cross-bred steers were allocated at random to receive either a concentrate based diet or a grass silage based diet. Lipids were extracted from dried faeces, separated into specific compound classes and analysed by gas chromatography/mass spectrometry, and CH4 production was estimated using the sulphur hexafluoride (SF6) technique. Steers fed the grass silage based diet consumed less feed (9.15 versus 11.43 kg dry matter (DM)/d; SED = 0.824; P

This study determined in vitro rumen CH4 production of perennial ryegrass grown within a well managed Irish dairy production system. Four strategies, consisting of two pre-grazing herbage mass (HM; high ∼2400 and low ∼1600 kg dry matter (DM)/ha) and two sward allowance (SA; high ∼20 and low ∼15 kg DM/cow/d) treatments, were compared throughout the grazing season using an in vitro rumen gas production technique. Samples were collected during five 22 d sampling periods (SP 1–5) throughout the growing season and analysed for in vitro rumen CH4 output, and total gas and volatile fatty acid production following 24 h of incubation with rumen fluid and artificial saliva. High HM was associated with lower organic matter digestibility and crude protein concentration compared with low HM, whereas SA had no effect on herbage composition. Methane output as ml/g DM incubated or digested was higher (P This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

In many in vitro studies feeds are dried in heated ovens with forced air ventilation and milled through a screen with 1 mm apertures to obtain a physically representative small sample. Drying methods involving heat have been shown to change the chemical composition of feeds, and it is possible that changes in the chemical composition during thermal drying could affect in vitro rumen CH 4 output measured on the samples. Hence, samples are often dried by freeze drying. The objective of this study was to compare effects of freeze drying at −55 °C for 72 h versus thermal drying at 40 °C for 48 h on the chemical composition and CH 4 output of perennial ryegrass samples collected at 5 stages of primary growth ( i.e. , 12 May, 26 May, 9 June, 23 June, 7 July) using an in vitro rumen gas production technique. The magnitude of the changes in chemical composition due to drying method was small and not biologically important, and drying method had no effect on CH 4 output. With advancing maturity at harvest, digestibility of the herbage declined. Methane output/g dry matter (DM) incubated decreased linearly while CH 4 output/g DM digested increased linearly with advancing grass maturity. Thermal drying on a range of grass samples had a similar effect to freeze drying on in vitro rumen CH 4 output, reflecting the small degree of change in chemical composition. This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

The effectiveness of the polyethylene stretch-film barrier to air infiltration is the major factor affecting the preservation of silage in bales. Three separate experiments investigated the effects of the number of layers of stretch-film cover, film colour, stretch extent, film type and frequency of bale handling on gas composition, surface mould growth and conservation characteristics of baled grass silages. Monitoring gas composition in bales during ensiling proved useful for assessing the success with which wrapped bales were stored anaerobically. Under good storage conditions the early stages of ensiling were characterized by the rapid reduction of O2 concentration in the bale and the creation of a CO2-rich environment. However, wrapping bales in only two layers of stretch-film failed to create the anaerobic conditions required for a successful fermentation and the inhibition of visible fungal growth. In contrast, a minimum of four layers of stretch-film were required to achieve suitably anaerobic conditions, but the additional benefits of applying more layers were relatively small. Under temperate climatic conditions with moderate solar radiation, film colour had little effect on the gas composition in baled silage. Likewise, the extent of stretching applied to the film at wrapping and film type had no influence on gas composition, baled silage quality or mould development. However, frequent mechanical handling of bales after wrapping had a negative effect on gas composition and surface mould growth, and thus should be kept to a minimum.

This study aimed to quantify the methane emissions and feed intake, performance, car- cass traits, digestibility, and rumen fermentation char- acteristics of finishing beef cattle offered diets based on whole-crop wheat (WCW) silages differing in grain content and to rank these relative to diets based on grass silage (GS) and ad libitum concentrates (ALC). In Exp. 1, a total of 90 continental crossbred steers (538 ± 27.6 kg of BW (mean ± SD)) were blocked by BW and assigned in a randomized complete block design to 1 of 6 treatments based on 4 WCW silages (grain-to- straw plus chaff ratios of 11:89 (WCW I), 21:79 (WCW II), 31:69 (WCW III), and 47:53 (WCW IV)), GS, and ALC. Increasing grain content in WCW silage resulted in a quadratic (P = 0.01) response in DMI, with a linear (P < 0.001) increase in carcass gain (CG; 577 (WCW I), 650 (WCW II), 765 (WCW III), and 757 g/d (WCW IV)). The G:F also increased linearly (P < 0.001) in response to increasing the grain content of WCW si- lage. A quadratic (P < 0.01) response in daily methane output (295 (WCW I), 315 (WCW II), 322 (WCW III), and 273 g/d (WCW IV)), measured using the sulfur hexafluoride tracer technique, was observed in response to increasing the grain content of WCW; however, lin- ear decreases were observed when expressed relative to DMI (P = 0.01) and CG (P < 0.001). Cattle offered GS exhibited carcass gains similar to those offered WCW silage diets and had greater methane emissions than cattle in any other treatment when expressed relative to DMI. Cattle offered ALC exhibited greater (P < 0.01) carcass gains and decreased (P < 0.001) methane emissions, irrespective of the unit of expression, com- pared with cattle in any of the silage-based treatments. In Exp. 2, rumen fermentation parameters were deter- mined using 4 ruminally cannulated Rotbunde-Holstein steers (413 ± 30.1 kg of BW) randomly allocated among WCW I, the average of WCW II and III (WCW II/III), WCW IV, and GS in a 4 × 4 Latin square design. Ru- minal pH and total VFA concentration did not differ across dietary treatments. Molar proportion of acetic acid decreased (P = 0.01), with propionic acid tend- ing to increase (P = 0.06) with increasing grain con- tent. It was concluded that increasing the grain content of WCW silage reduced methane emissions relative to DMI and CG and improved animal performance. How- ever, the relativity of GS to WCW in terms of meth- ane emissions was dependent on the unit of expression used. Cattle offered ALC exhibited decreased methane emissions and greater performance than those offered any of the silage-based treatments.

Aims: Grass silage is an important ruminant feedstuff on farms during winter. The ensilage of grass involves a natural lactic acid bacterial fermentation under anaerobic conditions, and numerous factors can influence the outcome of preservation. The aim of this study was to investigate the effect of dry matter concentration, ensiling system, compaction and air infiltration on silage bacterial community composition. Methods and Results: The impact of these factors was examined using conventional methods of microbial analysis and culture-independent Terminal Restriction Fragment Length Polymorphism (T-RFLP). Silage fermentation was restricted in herbage with a high dry matter concentration, and this was reflected in a shift in the bacterial population present. In contrast, ensiling system had little effect on bacterial community composition. Air infiltration, in the absence of compaction, altered silage bacterial community composition and silage pH. Conclusions: Dry matter concentration and the absence of compaction were the main factors affecting silage microbial community composition, and this was reflected in both the conventional culture-based and T-RFLP data. Significance and Impact of the Study: T-RFLP proved a useful tool to study the factors affecting ensilage. Apart from monitoring the presence or absence of members of the population, shifts in the relative presence of members could be monitored.

This experiment aimed to quantify the methane emissions and intake, digestibility, performance, and carcass characteristics of finishing beef cattle offered maize (Zea mays) silages harvested at 1 of 4 sequential stages of maturity and to relate these values to those obtained from animals offered an ad libitum concentrate-based diet. Sixty continental crossbred steers with a mean initial BW of 531 kg (SD 23.8) were blocked (n = 12 blocks) according to BW and allocated from within block to 1 of 5 dietary treatments in a randomized complete block design: maize silage harvested on September 13 (DM = 277 g/kg), maize silage harvested on September 28 (DM = 315 g/kg), maize silage harvested on October 9 (DM = 339 g/kg), maize silage harvested on October 23 (DM = 333 g/kg), and ad libitum concentrates (ALC). Diets based on maize silage were supplemented with 2.57 kg of concentrate DM daily, and ALC diets were supplemented with 1.27 kg of grass silage DM daily. Silage and total DMI were greater (P = 0.004) with maize silage harvested on September 28 than with any other treatment, which in turn did not differ. Advancing maize maturity at harvest did not affect BW or carcass gain, with the ALC diet exhibiting greater (P = 0.036) rates of carcass gain than any of the maize silage-based treatments. Apparent in vivo digestibility, determined using the AIA indigestible marker technique, was not affected by harvest maturity, with no linear or quadratic trends being identified. Digestibility of DM from the ALC diet was greater (P < 0.001) than with any of the maize silage treatments. Starch digestibility did not differ across maize silage maturities; however, a linear (P = 0.009) decrease in NDF digestibility was observed. Methane emissions, (g/d) measured using the sulfur hexafluoride tracer technique, were not affected by maize silage maturity. Methane emissions relative to DMI tended (P = 0.05) to decline with advancing maize silage maturity, with a similar decline observed when methane was expressed per kilogram of carcass gain. Advancing maize maturity did not result in significant linear or quadratic responses in methane output proportional to GE intake. The ALC diet resulted in less methane output than the maize silage treatments irrespective of the unit of expression. In conclusion, advancing maize harvest maturity did not affect beef cattle performance but reduced methane output relative to DMI and carcass gain. Cattle offered ALC exhibited greater rates of BW gain and less emission of methane compared with cattle offered any of the maize silage treatments.

The effects of 7 additive treatments on the fermentation and aerobic stability characteristics of wilted grass silage were studied under laboratory conditions. Treatments included no additive applied (untreated control), ammonium tetraformate at 3 and 6 L/t, homofermentative lactic acid bacteria alone ( ho LAB), a mixture of Lactobacillus buchneri plus homofermentative lactic acid bacteria ( he+ho LAB), and an antimicrobial mixture of sodium benzoate, sodium propionate, sodium nitrite, and hexamethylenetetramine at 2.5 and 5 L/t. Additives were compared across 3 consecutive harvests of 2 perennial ryegrass cultivars (AberDart and Fennema) following a 24-h wilt. Silos were opened after at least 100 d of ensilage and aerobic stability was assessed. Season of harvest had a large effect on grass composition at ensiling, producing herbages of relatively low (approximately 145g/kg), medium (approximately 250g/kg), and high (approximately 365g/kg) dry matter (DM) concentrations. Within harvests there were lesser differences between cultivars. The untreated control and ho LAB additive produced badly fermented silage from the low-DM herbages and well-fermented silage from the medium- and high-DM herbages. The ammonium tetraformate treatments produced both well-fermented and badly fermented silage from the low-DM herbages depending on cultivar, and consistently well-fermented silage from the medium- and high-DM herbages. The he+ho LAB silages had similar or slightly lower standard of fermentation than the untreated and ho LAB silages. The antimicrobial mixture produced more silages of lower standard of fermentation than the untreated control and ammonium tetraformate and ho LAB additives. All additive treatments, including the untreated control, failed to consistently increase residual water-soluble carbohydrate concentrations at silo opening. Ammonium tetraformate at 6 L/t was the most successful and he+ho LAB the least successful additive at increasing residual WSC concentrations. The ho LAB silages were generally the least aerobically stable. Silages treated with ammonium tetraformate at 6 L/t were relatively stable under aerobic conditions. The he+ho LAB additive and antimicrobial mixture had an inconsistent effect on aerobic stability. Overall, ammonium tetraformate at 6 L/t was the most effective additive evaluated in this study, producing generally well-fermented silage with the highest concentrations of residual WSC and an intermediate to long duration of aerobic stability.

The objectives of this study were to determine the relative effect of feeding corn silage (CS), fermented whole-crop wheat (FWCW), and urea-treated processed whole-crop wheat (UPWCW) compared with grass silage (GS), each supplemented with concentrates, on forage intake, ruminal fermentation, microbial protein synthesis, some plasma metabolites, and ruminal and total tract digestibility in cattle. Four ruminally fistulated steers with a mean BW of 509 kg (SD 6.3) were used in a 4 x 4 Latin square-designed experiment with each period lasting 21 d. The omasal sampling technique in combination with a triple marker method was used to measure nutrient flows to the omasum with Co-EDTA, Yb acetate, and indigestible NDF as liquid, small particle, and large particle phase markers, respectively. Microbial N flow was assessed from purine base concentrations. Steers fed CS, FWCW, and UPWCW consumed 2.7, 2.4, and 2.6 kg/d more (P or = 0.06). Total tract NDF digestibility was less (P < 0.05) for UPWCW than the other forages, with GS being greatest and CS and FWCW being intermediate. Starch intake was less (P < 0.001) for GS than the other forages, but there was no effect of forage on omasal starch flow (P = 0.23) or ruminal digestibility (P = 0.88). Flow of non-NH(3)-N and microbial N was greater (P < 0.05) for CS, FWCW, and UPWCW than GS. Efficiency of microbial N synthesis was greater (P < 0.05) for FWCW than GS and CS, with UPWCW being intermediate. Plasma beta-hydroxybutyrate concentrations were greatest with CS and least for GS (P < 0.001), whereas concentrations of plasma urea were least for CS and greatest for UPWCW (P < 0.001). In conclusion, feeding alternative forages to GS can significantly increase feed DMI and alter rumen fermentation and site of nutrient digestion when offered to cattle supplemented with 3 kg of concentrate daily.

A range of LDPE/LLDPE films were manufactured by blown and cast extrusion, which were then uni-axially stretched at regular intervals. The films were analysed to determine the change of diffusion, solubility and permeation coefficient, and the correlation between crystallinity and molecular orientation. It was found that films exhibited a decrease in permeation coefficient with increased uni-axial stretch as a result in change in crystal type and higher molecular orientation, resulting in a decrease of diffusion and solubility coefficient. This paper shows how double yield phenomena present in the uni-axial stretching of the LDPE/LLDPE films affect the permeation properties. Copyright © 2008 John Wiley & Sons, Ltd.

The effects of varying the grain (G) to straw (S) ratio (G:S) of whole-crop wheat and barley silages on intake and digestibility and whole-crop barley silage on rumen fermentation characteristics were examined in two parallel studies. For the intake and digestibility study, eight Aberdeen Angus cross-bred steers (mean bodyweight 407 kg (S.D. 24.2)) were used in two (barley and wheat) 4 × 4 Latin Square designed experiments. The dietary treatments were four G:S ratios: 0:100, 30:70, 60:40 and 90:10. Intake of grain linearly increased ( P P P >0.05) was observed in total dry matter (DM) intake (DMI) or in DMI per kg liveweight. There was a positive linear ( P P P P P P P P P P P iso - and n -butyric acid, iso - ( P n - ( P P P P P >0.05) was found on the fractional clearance rates of DM, OM, aNDFom or starch or on liquid passage rate. It is concluded that increasing the G:S ratio in whole-crop wheat or barley silage linearly increased the intake of digestible nutrients for both wheat and barley and increasing the G:S ratio for whole-crop barley increased the concentration of fermentation products (total VFA, ammonia and the molar proportions of the VFAs, except acetic acid) in the rumen.

The composition of baled silage frequently differs from that of comparable conventional silage. A factorial experiment was conducted with three wilting treatments (0, 24 or 48 h) × three ensiling systems [unchopped grass in bales, unchopped grass in laboratory silos (LS), precision-chopped grass in LS] × six stages of ensiling to (i) confirm that the fermentation of unchopped grass in LS could be used as an adequate model for baled silage fermentation, (ii) quantify the differences between baled silage and silage made from precision-chopped herbage across a range of dry-matter contents and (c) quantify the fermentation dynamics within the various treatments. The onset of fermentation as evidenced by the accumulation of fermentation products and the decline in pH were slower (P

Aims: Grass silage is the product formed by a natural lactic acid bacterial fermentation when grass is stored under anaerobic conditions, and represents an important ruminant feedstuff on farms during winter. Of the two commonly employed methods of ensiling forage, baled silage composition frequently differs from that of comparable precision-chop silage reflecting a different ensiling environment. The aim of this study was to investigate the dynamics of the silage fermentation in wilted grass and between ensiling systems. Methods and Results: Fermentation dynamics were examined using traditional methods of silage analyses, including microbial enumeration and analysis of fermentation products, and culture-independent terminal restriction fragment length polymorphism (T-RFLP). A successful fermentation was achieved in both systems, with the fermentation (increase in lactic acid bacteria and lactic acid concentration, decrease in pH) proceeding rapidly once the herbage was ensiled. Conclusions: Under controlled conditions, little difference in silage quality and microbial composition were observed between ensiling systems and this was further reflected in the T-RFLP community analysis. Significance and Impact of the Study: T-RFLP proved a potentially useful tool to study the ensilage process and could provide valid support to traditional methods, or a viable alternative to these methods, for investigating the dynamics of the bacterial community over the course of the fermentation.

Seventy beef steers, mean initial live-weight 424 (S.D. 33.0) kg, were blocked by live-weight and breed and allocated to one of 5 dietary treatments in a randomised complete block design. Treatments, including supplementation with 3 kg concentrates/head/day, were grass silage (GS), maize silage (MS), fermented whole-crop wheat (FWCW), urea-treated, processed whole-crop wheat (UPWCW), and ad libitum concentrates supplemented with 5 kg grass silage/head/day (ALC). The grain in urea-treated, processed whole-crop wheat (WCW) was cracked and the crop ensiled with a urea plus urease-based additive. The mean dry matter (DM) of the grass silage, maize silage, fermented WCW and urea-treated, processed WCW was 174, 315, 404 and 716 g/kg, respectively. Total DM intake and carcass growth were lowest for GS (P

This experiment aimed to quantify the relative intake, digestibility, rumen fermentation, performance and carcass characteristics of beef cattle fed diets based on good quality whole-crop wheat and barley silages, each harvested at two cutting heights, and to rank these relative to good quality maize silage and an ad libitum concentrates-based diet. Ninety beef steers, initial live-weight 438 ± 31.0 kg, were allocated to one of the following dietary treatments in a randomised complete block design: maize silage (MS), whole-crop wheat harvested at a normal cutting height (WCW) (stubble height 0.12 m) or an elevated cutting height (HCW) (stubble height 0.29 m), whole-crop barley harvested at a normal cutting height (WCB) (stubble height 0.13 m) or an elevated cutting height (HCB) (stubble height 0.30 m), each being supplemented with 3 kg concentrates/head/day, and ad libitum concentrates (ALC) supplemented with 5 kg grass silage/head/day for the duration of the 160-day study. Mean dry matter (DM) of the maize silage, whole-crop wheat, head-cut wheat, whole-crop barley and head-cut barley was 301, 488, 520, 491 and 499 g/kg, respectively. There were no differences in total DM intake among treatments, or in rumen fermentation characteristics (except ammonia), or in DM digestibility among the forage-based treatments. Neutral detergent fibre digestibility was lower (P

The objective was to determine the relative effects of a specific increase in grass silage sucrose concentration, or a specific supplement of a starch-based concentrate, on rumen fermentation and nutrient supply to the omasum in beef cattle. Four ruminally cannulated Holstein–Friesian steers were fed grass silage only (G), G plus 3 kg concentrates/day (GC), G plus 90 g sucrose/kg dry matter (DM) (GS) and G plus 90 g sucrose/kg DM plus 3 kg concentrates/day (GCS) in a 4 × 4 Latin Square design experiment. Omasal flow was estimated using Co-EDTA, Yb-acetate and indigestible neutral detergent fibre (INDF) as digesta flow markers and purine bases as microbial markers. Concentrate supplementation reduced (P

The extent of visible fungal growth and the identity of the predominant fungi causing spoilage of baled grass silage were recorded on 180 farms in Ireland. Fungal growth was evident on bales on 174 of the 180 farms visited and on 331 of the 360 bales examined. The mean proportion of surface area of bale, that was affected, was 0·06. Silage-making method, storage characteristics and geographical location were significantly associated with the level of fungal contamination on bales. Fungal contamination was higher (P

Perennial ryegrass (Lolium perenne L.) is by far the most widely sown grass species in Ireland. Genotype · environment (G · E) interactions are a frequent occurrence in herbage yield evaluations. The objectives were to determine (i) the nature and relative magnitudes of the pertinent G · E interaction variance components for dry matter yield of perennial ryegrass sward plots in Ireland and (ii) the optimal allocation of replicates, locations and years in a testing programme. Sixteen perennial ryegrass cultivars were sown at six locations throughout Ireland between 2000 and 2004. Plots from each sowing were harvested for 2 consecutive years under a simulated mixed grazing and conservation management programme. The largest component of the G · E variance was generally genotype · location · year emphasizing the need for evaluation of genotypes across locations and years to adequately characterize genotypes for differences in yield. Relative differences among genotypes from year to year and location to location were due mainly to changes in genotype rankings. Weather was estimated to have a greater effect on annual variation in herbage yield than age of stand. The optimum allocation of resources for a testing programme was estimated at four replicates per location, and either two locations and 3 sowing years or three locations and 2 sowing years with 2 harvest years for each sowing year. The most appropriate option depends on the relative importance of time vs. financial resources.

Forage dry matter yield (DMY) is a high-priority trait in breeding perennial ryegrass (Lolium perenne L.). However, determining dry matter concentration is highly labor intensive. For a similar level of resources, indirect selection based on fresh matter yield (FMY) would allow a greater number of replicates, genotypes, or both to be evaluated. Our objective was to estimate the effi ciency of indirect selection for DMY based on FMY of pure perennial ryegrass sward plots. Over a 14-yr period, replicated trials, containing perennial ryegrass genotypes of similar ploidy and maturity category, were sown in Ireland and assessed for DMY and FMY at each harvest over two consecutive years. Forage was generally surface dry when harvested. The estimated effi ciency of indirect selection based on two replicates and comparable selection intensity was high (≥0.80). Simulation models indicated that resources would be used more effi ciently by evaluating more genotypes than by increasing the number of replicates. For example, doubling the number of plots to increase the number of replicates from two to four indicated an increase in the effi ciency of indirect selection from a mean 0.88 to 0.94. However, doubling the number of plots and including more genotypes, facilitating greater selection intensity, indicated an increase in the effi ciency of indirect selection from a mean 0.88 to 1.04. This study indicates that FMY can be used successfully as an indirect selection method of increasing DMY in perennial ryegrass swards.

The extent of visible fungal growth and the identity of fungi causing spoilage of baled grass silage were recorded regularly through a winter feeding period in Ireland. The study was conducted from November 2003 to March 2004 on 50 farms differing in farming systems and geographical locations in the Irish Midlands and two bales were examined in detail on each farm ( n =100 bales). Visible fungal growth was present on 90 of the 100 bales examined. There were more fungal colonies visible on bales in March (mean, 8) than in November (mean, 4) (P 0.05). Fungal contamination was higher (P Penicillium roqueforti which represented 0.43 of all fungal colonies observed and was present on 0.78 of bales. The proportion of bale surface areas visibly colonised by P. roqueforti increased (P Schizophyllum commune , mucoraceous moulds and Pichia fermentans . Redundancy analysis showed that the distribution of fungi on bales was best explained by the concentrations of ethanol and lactic acid, dry matter content, bale tying, month of bale feed-out, age of bales, polythene film damage, ryegrass dominance, bale storage location and volatile fatty acid concentrations. Forward selection of these silage characteristics showed that butyric acid concentration and age of bales contributed significantly (P P. roqueforti occurrence was positively correlated to higher concentrations of propionic and butyric acids, to month of bale feed-out and to bale age. S. commune was more commonly isolated from bales made from ryegrass dominant swards, that had visibly damaged polythene film, that were stored in farmyards and from silage with a lower lactic acid concentration. Overall, a high incidence of visible fungal growth was recorded on bales throughout the winter season and the extent of colonisation and fungal species occurring were not random. To prevent fungal spoilage of baled silage, the focus of best farm practice should be to provide low oxygen conditions in well wrapped and carefully managed bales.

Summary The chemical composition of baled silage frequently differs from that of comparable conventional silage. The extents of wilting, chopping, compaction and air infiltration potentially contribute to these differences in conservation characteristics. An experiment was organized in a 3 (0, 24 or 48-h wilting to influence herbage dry-matter content) × 2 (unchopped or chopped) × 2 (with or without compaction) × 2 (with or without air infiltration) factorial arrangement of treatments, to elucidate the relative effects of these factors on the conservation characteristics of ensiled grass. Dry-matter content of herbage and infiltration of air had a greater effect on silage conservation characteristics than chopping and compaction. The main interactions were between wilting and air infiltration, wilting and compaction, and compaction and air infiltration. Air infiltration stimulated a secondary fermentation in the unwilted herbage, reflected in a large increase (P

This experiment quantified the effects of: (i) heading date of perennial ryegrass, (ii) grazing frequency in spring and (iii) date of silage harvest, on the ensilability of herbages harvested for silage, and on the conservation and estimated nutritive value of the resultant silages. Replicated field plots with two perennial ryegrass mixtures (intermediate- and late-heading cultivars) were subjected to three spring-grazing regimes (no grazing, grazing in late March and grazing in both late March and late April) and were harvested on four first-cut harvest dates between 20 May and 21 June. Herbage from each of the four replicates of these 24 treatments was precision-chopped and ensiled unwilted and with no additive in laboratory silos. Herbage from the sward with the intermediate-heading cultivar had a higher (P

The objective was to determine the feeding value of high moisture grain as an alternative to dry grain for finishing beef cattle. Winter wheat grain was harvested sequentially for rolling, acid treatment and ensilage (ER; 705 g dry matter (DM)/kg), urea whole grain treatment and anaerobic storage (UN; 746 g DM/kg) and whole grain propionic acid treatment and aerobic storage (rolled before feeding; PR; 849 g DM/kg). Friesian steers ( n = 120; mean starting live-weight 518 kg) were allocated on a live-weight basis to 12 replicate blocks and then randomly assigned from within blocks to ten treatments. Treatments were grass silage offered ad libitum together with (i) no wheat, (ii–iv) PR at 3 or 6 kg/head daily, or ad libitum , (v–vii) UN at equivalent DM allowances to (ii) and (iii) above, or ad libitum , (viii–x) ER at equivalent DM allowances to (ii) and (iii) above, or ad libitum . Mean daily live-weight gains were 852 (ER), 726 (UN) and 855 g (PR) (s.e. = 65.5; P P P ad libitum was 7.8, 8.3 and 8.2 kg (s.e. = 0.10; P P

Challenges currently faced by beef producers in Ireland include reducing their adverse environmental impact and maintaining farm economic margins. Fertilizers are essential for productive farming but they can be harmful to the environment when inappropriately or excessively applied to crop and pasture land. A linear programming model was used to identify financially optimal strategies for calf-to-stocker and calf-to-finish beef cattle production in high- and low-price market scenarios. The high-price scenario resulted in an increase in gross margin of $1,700 and $13,000 on a 40-ha farm for the stocker and finisher options, respectively. The impacts of these systems on environmental indicators were investigated through farm simulation. In general, the high-price scenarios were more intensive and had greater environmental impacts when compared to the low-price scenarios. Nitrogen leaching losses were quantitatively the most important environmental indicator on well-drained soils with a maximum annual loss of 72 kg N/ha. Volatilization and denitrification losses of nitrogen (N) were also relatively high where more intensive production was practiced with annual losses of 48 and 23 kg N/ha, respectively, in the most intensive scenario identified. Predicted phosphorus losses were small although annual accumulations in the soil of up to 7.5 kg P/ha may lead to greater losses in the future. On poorly drained soils, volatilization losses were greatest with leaching losses in this case the lowest of the loss pathways investigated. Further reduction in inorganic nitrogen application has the potential to reduce N losses, but predicted concomitant reductions in farm gross margins were also considerable.

The viable fungal spora of baled grass silage was quantified and identified. One group of bales (Experiment 1, n = 15) was wrapped in 6 layers of polythene, and was handled and stored for 6 weeks under well-managed conditions. This silage was free of visible fungal contamination after 6 weeks and the film surrounding these bales was visibly undamaged. Moulds were cultured from 9/15 bales, while yeasts were cultured from all bales. A second group of bales (Experiment 2, n = 18) from 9 farms, were wrapped in 4 layers of film, handled and stored for 8 months using normal on-farm procedures. Visible fungal contamination was observed on the surface of most of these bales (15/18) and the film surrounding some bales (8/18) was damaged. In silage sampled from parts of bales that were visually non-mouldy, yeasts were cultured from all bales and moulds from 15/18 bales. Bales in the well-managed group (Experiment 1) had numerically lower numbers of yeasts (mean: 9.7 × 10 3 colony-forming units per gram of silage, cfu/g) and lower numbers of moulds ( 1 cfu/g) compared to the normal on-farm produced group (2.3 × 10 5 yeast and 1.5 × 10 5 mould cfu/g; Experiment 2). The most common yeasts in each group of bales were Saccharomyces exiguus (12/15 bales; Experiment 1) and Pichia fermentans (11/18 bales; Experiment 2) and their numbers in all bales ranged from 0 to 10 5 cfu/g (mean: 8.4 × 10 3 ) and 0 to 1.5 × 10 6 cfu/g (mean: 1.2 × 10 5 ), respectively. Bales contaminated with visible mould growth on their surfaces had higher yeast and mould numbers in visually non-mouldy parts adjacent to the contaminated areas than bales that had no visible mould. Mould numbers were higher (P Penicillium roqueforti was not cultured from the well-managed bales, but it was the most common mould in bales prepared using normal on-farm procedures (13/18 bales); propagule numbers in bales ranged from 0 to 7.1 × 10 5 (mean: 1 × 10 5 cfu/g). Low numbers of mould propagules, the absence of viable P. roqueforti spores and the absence of mould growth in well-managed bales, emphasises the benefit of applying sufficient film and preventing it from becoming damaged during bale handling and storage.

An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) multi-mycotoxin analytical method was developed to simultaneously identify and quantify 20 mycotoxins in grass silages, inclusive of mycotoxins that are currently regulated in European Union feeds. Extraction of mycotoxins from dried grass silages was performed using of a modified QuEChERS extraction employing an acidified aqueous extraction (0.1 N HCl) with no further clean-up. Following chromatographic separation, analytes were detected using a fast polarity-switching MS/MS method that allowed both positive and negative ions to be analysed from a single injection, thus the reducing time and cost of analysis. The limits of detection and quantification ranged between 3 µg kg(-1) DM (aflatoxin B1, beauvericin and enniatin A and A1) and 200 µg kg(-1) DM (deoxynivalenol), and between 10 µg kg(-1) DM (aflatoxin B1, beauvericin and enniatin A1) and 500 µg kg(-1) DM (deoxynivalenol), respectively. Inter-assay accuracy and precision ranged between 90% and 107% and between 3.9% and 15.0% CV, respectively. The accuracy of the method was assessed through the application to a range of incurred samples in an inter-laboratory study.

This work examines the digestion of advanced growth stage grass silage. Two variables were investigated: particle size (greater than 3 cm and less than 1 cm) and rumen fluid addition. Batch studies indicated particle size and rumen fluid addition had little effect on specific methane yields (SMYs). In continuous digestion of 3 cm silage the SMY was 342 and 343 L CH 4 kg −1 VS, respectively, with and without rumen fluid addition. However, digester operation was significantly affected through silage floating on the liquor surface and its entanglement in the mixing system. Digestion of 1 cm silage with no rumen fluid addition struggled; volatile fatty acid concentrations rose and SMYs dropped. The best case was 1 cm silage with rumen fluid addition, offering higher SMYs of 371 L CH 4 kg −1 VS and stable operation throughout. Thus, physical and biological treatments benefited continuous digestion of high fibre grass silage.

This study demonstrates the use of a mannitol rich ensiled grass press juice (EGPJ) as a renewable carbon substrate for polyhydroxyalkanoates (PHA) production in shaking flask experiments and fed-batch stirred tank reactor cultivations. Fed-batch cultivations of Burkholderia sacchari IPT101 using EGPJ as sole carbon source produced 44.5 g/L CDW containing 33% polyhydroxybutyrate (PHB) in 36 h, while Pseudomonas chlororaphis IMD555 produced a CDW of 37 g/L containing 10% of medium chain length polyhydroxyalkanoates (mcl-PHA) in 34 h. PHB and mcl-PHA extracted from B. sacchari IPT101 and P. chlororaphis IMD555, grown on EGPJ, had a molecular weight of 548 kg/mol and 115.4 kg/mol, respectively. While mcl-PHA can be produced from EGPJ, PHB production is more interesting as there is a 4-fold higher volumetric productivity compared to mcl-PHA.

Recent reform of European agricultural policy has resulted in substantial changes to the criteria by which premia payments are made. Beef farmers, who have been particularly dependent on premia payments to maintain margins, must re-evaluate their systems to identify optimal systems in these new circumstances. A mathematical model, the Grange Beef Model, is presented and used to identify optimal beef production systems in Ireland. The objective function maximises farm gross margin and the model is primarily constrained by animal nutritional requirements. Model applications are illustrated through the analysis of a series of scenarios concerning variation in beef and concentrate prices; technical development through the integration of an alternative forage and the impacts of participation in an agri-environmental scheme.

Ten bales of grass silage were cored at eight pre-determined positions and the mould and yeast propagules were enumerated. Both mould and yeast numbers varied greatly between and within individual bales. Yeast colony forming units (cfu) showed greater variability between (s.e. 1.44 log 10 cfu/g) than within bales (s.e. 0.53 log 10 cfu/g). This variation between and within bales was statistically significant (P

There are potential advantages and disadvantages associated with grazing spring perennial ryegrass swards designated for first-cut silage. These may differ for intermediate-heading (0·50 ear emergence in the second half of May) and late-heading (0·50 ear emergence in the first half of June) cultivars. The interactions between cultivar type, spring-grazing frequency, silage-harvest date and year were examined in an experiment with a randomized complete block (n = 4) design with a factorial arrangement of treatments, conducted in Ireland. The factors were (i) two perennial ryegrass mixtures: intermediate- vs. late-heading cultivars, (ii) three spring-grazing regimes: no grazing, grazing in mid-March or grazing in both mid-March and mid-April, (iii) four first-cut silage-harvest dates that were at c. 10-d intervals from 19 May and (iv) 2 years (1998 and 1999). The effects of cultivar mixture on herbage mass of the swards in spring were small and not statistically significant. The late-heading cultivars provided lower amounts of herbage dry matter for harvesting for first-cut silage but herbage with higher in vitro organic digestibility values compared with intermediate-heading cultivars. To achieve the same amount of herbage for silage, the late-heading cultivars needed to be harvested 8 d later than the intermediate-heading cultivars. Even with this delay in harvest date, the late-heading cultivars had higher in vitro organic digestibility values than the intermediate-heading cultivars. The late-heading cultivars could be harvested up to 30 d later and produce a higher amount of herbage for first-cut silage with similar digestibility values compared with the intermediate-heading cultivars.

Grass silage is a key source of forage for over-wintering livestock in Ireland. In the early 1990s Schizophyllum commune emerged as a contaminant of big-bale silage. A fungus rarely observed in Irish woodlands, S. commune is now commonly found on baled silage throughout Ireland and is also recorded on silage in Britain. Characteristics of the fungus on bales are described and potential consequences of its occurrence on silage are discussed.

This study investigated the effect of substituting grass silage (C3 photosynthetic plant product) with maize silage (C4 photosynthetic plant product) on the natural abundance carbon (delta13C) and nitrogen (delta15N) stable isotope composition of bovine muscle tissue. Forty-five continental crossbred heifers were assigned to one of three diets consisting of 3 kg of a barley-based concentrate plus grass silage, maize silage or an equal mixture (dry matter basis) of grass silage and maize silage, fed ad libitum, for 167 days. Substitution resulted in less negative delta13C values (P

This study investigated the effect of trace element addition to mono-digestion of grass silage at high organic loading rates. Two continuous reactors were compared. The first mono-digested grass silage whilst the second operated in co-digestion, 80% grass silage with 20% dairy slurry (VS basis). The reactors were run for 65weeks with a further 5weeks taken for trace element supplementation for the mono-digestion of grass silage. The co-digestion reactor reported a higher biomethane efficiency (1.01) than mono-digestion (0.90) at an OLR of 4.0kgVSm(-3)d(-1) prior to addition of trace elements. Addition of cobalt, iron and nickel, led to an increase in the SMY in mono-digestion of grass silage by 12% to 404LCH4kg(-1)VS and attained a biomethane efficiency of 1.01.

Fasciolosis caused by Fasciola hepatica is generally a subclinical infection of dairy cows and can result in marked economic losses on Irish dairy farms. This study investigated the exposure to F hepatica in 237 dairy cow herds, using an in-house antibody-detection ELISA applied to bulk tank milk (BTM) samples collected in the autumn of 2012. A total of 364 BTM samples were collected from 237 different herds, with 127 farmers submitting BTM samples in two consecutive months. Analysis of the BTM samples indicated that 67 per cent (n= 159) of the dairy herds had been exposed to F hepatica. Rainfall, temperature and soil types were significantly different between the exposed and non-exposed herds (P0.05), highlighting the role of these variables to the exposure to F hepatica. Among the 127 herds that provided two monthly milk samples, 83 herds were exposed to F hepatica and 82 increased their F hepatica antibody levels at the later sampling time (P0.01).The findings of this study confirm the high prevalence of F hepatica antibodies in Irish dairy herds and show the rise in antibody levels during autumn. This study is the first step towards assessing the spatiotemporal pattern of fasciolosis in dairy herds in Ireland.

The scale of damage caused by vertebrates to the plastic wrap on baled silage was evaluated on Irish farms. A survey was conducted on 300 farms representative of farming systems and geographical locations throughout Ireland. The scale of damage was classified as farms with 0%, 1-10%, 11-50% or 51-100% of bales with holes in the plastic wrap caused by birds. The proportion of farms within these four classes with damage caused by birds during the short interval between wrapping and removal from the field to storage was 47%, 37%, 15% and 1% of the total, respectively. Correspondingly, during the subsequent storage prior to feedout, bird damage was 37%, 50%, 12%, and 1%. Similarly, the proportions for damage throughout long-term storage due to cats were 71%, 23%, 6% and 0%, while the incidence of damage caused by rats, dogs and farm livestock was comparatively small. The stored bales were fenced against livestock on 86% of farms, while netting, bale painting and other protection methods were used to discourag...

The objectives of this study were (i) to examine the effects on rumen and blood variables when grass silage (GS) was replaced with whole crop fodder beet silage (FBS) in the diet of beef cattle, and (ii) an abrupt change from GS to FBS. Six rumen-fistulated Friesian steers (initial bodyweight (BW) 416 kg, SD 43) were offered GS ad libitum for four weeks. The dry matter (DM) consumed daily by each animal in that period (14.3 g/kg BW) was used as the daily allowance for that animal for three consecutive two-week periods, during which the animals were offered diets consisting of increasing proportions (420, 880 and 1000 g/kg) of FBS DM in the total DM. FBS was then offered ad libitum for 14 days. Cattle were then offered GS ad libitum for 14 days, after which GS was substituted with FBS for 14 days. The DM content (g/kg) and contents (g/kg DM) of organic matter, crude protein and total volatile fatty acids (VFA) were 220 and 174, 905 and 749, 153 and 115, and 26 and 75 for GS and FBS, respectively. Animals fed the diets of 0, 420, 880 and 1000 g FBS DM/kg DM had rumen pH, concentrations of ammonia (mg/l), l-lactic acid (mmol/l), d-lactic acid (mmol/l) and VFA (mmol/l) of 6.44, 6.18, 6.61 and 6.75 (linear p

This paper outlines the findings of a study on the influence of cement content (275–425 kg/m3) and water/cement ratio (0·45 to 0·75) on the durability of concrete exposed to silage effluent. The test facility exposed concrete specimens to a controlled flow of effluent such that the volume of effluent in each 28 day cycle of exposure simulated one year's volume and expected period of effluent flow at the front of a well-drained 200 t horizontal silo. The relative performance of the concrete mixes was assessed over 10 cycles through measurement of saturated mass loss and surface depth change. The saturated mass loss measurement gave more consistent results. Optimum performance was recorded in concretes of cement content 325 and 375 kg/m3with water/cement ratios of 0·55 and 0·50, respectively. The studies indicate that water/cement ratio is a more critical variable than cement content. Deterioration increased significantly when the water/cement ratio exceeded 0·5. Increasing the cement content beyond the minimum recommended value in current national specifications (350 kg/m3) did not lead to a reduction in mass loss rate. The benefits of high cement content concretes is questioned, therefore, not least because of the increased risk of early-thermal cracking. It is postulated that specifications should limit the maximum water/cement ratio and both maximum and minimum cement content.

A biomethane potential (BMP) assessment of grass silage yielded 107 m(3)CH4 t(-1). Long term mono-digestion of grass silage can suffer due to a deficiency in essential nutrients; this may be overcome by co-digesting with slurry. Mono-digestion of slurry achieved a low yield of 16 m(3)CH4 t(-1). BMP assessments at a range of co-digestion ratios indicated methane yields were between 4% and 11% lower than the values calculated from mono-digestion. This paper suggests that co-digestion of the majority of slurry produced from dairy cows in Ireland with grass silage quantities equivalent to 1.1% of grassland on a 50:50 volatile solids basis would generate over 10% renewable energy supply in transport (RES-T). The industry proposed would equate to 170 digesters each treating 10,000 t a(-1) of grass silage and 40,000 t a(-1) of slurry from dairy cows.

A factorial experiment was carried out to evaluate the effects of level of nitrogen (N) application to grassland and subsequent treatment of the herbage at ensiling with formic acid on the rate of silage fermentation, dry-matter (DM) recovery, aerobic stability and effluent production. Herbage from the primary regrowth of predominantly perennial ryegrass swards received either 72 (LN), 126 (MN) or 180 (HN) kg N ha−1. The herbages were harvested and yield estimated after a 50-day regrowth interval. After storage for 24 h in polythene bags, the herbages were ensiled, unwilled, in laboratory silos (6 kg capacity) either untreated (UT) or treated with formic acid (F) at 3 ml (kg herbage)−1. Three silos per treatment were opened and sampled on days 1, 3, 6, 15, 50 and 105 after ensiling. The mean herbage yields for the LN, MN and HN swards were 5.2, 6.3 and 6.2 (s.e. = 0.27) t DM ha−1 and there was no carryover effect of nitrogen treatment on the yield of a subsequent 22-day regrowth harvested on 2 September. As level of fertilizer N application increased, concentrations in the herbage at mowing of crude protein, nitrate and ash increased, DM decreased and water-soluble carbohydrate and in vitro DM digestibility remained unchanged. Increasing the rate of N fertilizer to the sward resulted in higher silage pH (P 0.05) on DM recovery. It is concluded that the rate and extent of pH decline was reduced with increasing N application, associated with increased buffering capacity and decreased DM concentrations of the herbage at ensiling. However, increasing the level of N fertilizer applied increased DM recovery and effluent output, and improved aerobic stability of the resulting silages.

Government policies relating to red meat production take account of the carbon footprint, environmental impact, and contributions to human health and nutrition, biodiversity and food security. This paper reviews the impact of grazing on these parameters and their interactions, identifying those practices that best meet governments’ strategic goals. The recent focus of research on livestock grazing and biodiversity has been on reducing grazing intensity on hill and upland areas. Although this produces rapid increases in sward height and herbage mass, changes in structural diversity and plant species are slower, with no appreciable short-term increases in biodiversity so that environmental policies that simply involve reductions in numbers of livestock may not result in increased biodiversity. Furthermore, upland areas rely heavily on nutrient inputs to pastures so that withdrawal of these inputs can threaten food security. Differences in grazing patterns among breeds increase our ability to manage biodiversity if they are matched appropriately to different conservation grazing goals. Lowland grassland systems differ from upland pastures in that additional nutrients in the form of organic and inorganic fertilisers are more frequently applied to lowland pastures. Appropriate management of these nutrient applications is required, to reduce the associated environmental impact. New slurry-spreading techniques and technologies (e.g. the trailing shoe) help reduce nutrient losses but high nitrogen losses from urine deposition remain a key issue for lowland grassland systems. Nitrification inhibitors have the greatest potential to successfully tackle this problem. Greenhouse gas (GHG) emissions are lower from indoor-based systems that use concentrates to shorten finishing periods. The challenge is to achieve the same level of performance from grass-based systems. Research has shown potential solutions through the use of forages containing condensed tannins or establishing swards with a high proportion of clover and high-sugar grasses. Relative to feeding conserved forage or concentrates, grazing fresh grass not only reduces GHG emissions but also enhances the fatty acid composition of meat in terms of consumer health. It is possible to influence biodiversity, nutrient utilisation, GHG emissions and the nutritional quality of meat in grass-based systems, but each of these parameters is intrinsically linked and should not be considered in isolation. Interactions between these parameters must be considered carefully when policies are being developed, in order to ensure that strategies designed to achieve positive gains in one category do not lead to a negative impact in another. Some win–win outcomes are identified.