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Lactic acid bacteria (LAB) are commonly used as silage inoculants. Manganese sulphate (MnSO4) has been proposed to protect certain LAB during oxygen exposure and improve silage aerobic stability (ASTA). The aim of the present study was to assess the efficacy of inoculants in preservation of different forages. A short‐term screening trial investigated the effect of 24 additive treatments, compared to a negative control, on ensiling perennial grass in mini‐silos (2.75 L) for 7 d. The additive treatments comprised different ratios of Lactiplantibacillus plantarum [IMI 507026, IMI 507027, and IMI 507028] and Pediococcus pentacaceus [IMI 507024 and IMI 507025], with or without MnSO4. Target parameters, such as low levels of fresh matter loss, pH, acetic acid, ammonia‐nitrogen fraction (NH3–N/Total N), and high levels of lactic acid and ASTA, were considered for treatment selection. Eight treatments were selected based on a principal component analysis and hierarchical clustering of the target parameters. These selected treatments subsequently underwent a 100 d long‐term trial using lucerne, perennial grass, and perennial grass‐white clover forages. All silages treated with the eight additives exhibited an improved homolactic fermentation and a lower (p <.001) pH, acetic acid, and ethanol content than the control. Although DM losses and ASTA markedly improved in the treatments containing MnSO4 in the short‐term trial, these effects were not observed in the long‐term trial. These outcomes suggest that the selected additives can improve silage fermentation quality across a broad range of forages, but further studies are required to assess the impact of MnSO4 on ASTA. [ABSTRACT FROM AUTHOR]

Urine patches from grazing ruminants contain high concentrations of nitrogen (N) and are the main source of N leaching from grazed pastoral farming systems. While there have been various options identified to substantially reduce N leaching, in general these practices increase the cost of production or reduce production per hectare. In New Zealand, multi‐species pastures were evaluated as a cheaper option that would potentially retain productivity. Early research showed these pastures had lower urinary N excretion from grazing animals and increased plant N uptake, compared with standard New Zealand perennial ryegrass/white clover (PR‐WC) pastures. Further research highlighted the beneficial attributes of the pasture herb narrow‐leaved plantain (Plantago lanceolata; PL), specifically: reduced urine N concentration, reduced urine N excretion, and reduced rate of soil nitrification. Significant reductions (14%–89%) in N leaching were found from cow urine applied to lysimeters with pastures including PL, compared with PR‐WC pasture. Paddock‐scale measurements confirmed the effects of PL, with 20%–60% lower N leaching when PL comprised 30%–40% of the dry matter (DM) of PL‐PR‐WC grazed pastures. There were no negative effects on milk production and composition when feeding PL to dairy cows, but small positive effects on fatty acid profiles. However, weed and pest management, palatability and persistence remain challenging in pastures containing PL on commercial farms. Management options need to be clarified to ensure successful establishment and maintenance of PL. Additionally, the cultivar differences in secondary compounds and their impact on nitrification rate and N leaching need to be better understood. [ABSTRACT FROM AUTHOR]

The local abiotic and environmental conditions of a grass‐based farming system may influence the agricultural benefits of mixtures in comparison to pure stands. We investigated the effects of species identities and interactions between grass, legume, and herb species on dry matter yield and sward digestibility and explored how contrasting environments may affect these relationships. We established experimental plots across 11 mixtures and 4 monocultures of perennial ryegrass (Lolium perenne L.), chicory (Cichorium intybus L.), white clover (Trifolium repens L.), and red clover (Trifolium pratense L.) established at two seeding densities in two sites Brody and Szelejewo (Poland) and managed them over a 3‐year period. The two sites were close geographically and had similar climates, but differed in soil types (Luvisols and Cambisols, respectively). We confirmed that the annual DM yields were generally higher on Cambisols soil as compared to Luvisols soil; both individual species effects and species interaction strengths differed across the two contrasting environments. The predicted annual DM yield for the 4‐species mixtures in general gave comparable or higher yields compared to monocultures across the 3 years, with the mixtures giving around 10%–30% higher yields than the weighted average of the monocultures of the constituent species. Analysing the transgressive overyielding it turned out that there was no significant difference between the 4‐species mixtures and best performing monoculture. The benefits of species diversity in our study was greater on less productive site because we found larger overyielding of the 4‐species sward on the Luvisols soil than on the Cambisols soil. Additionally, the effect of mixtures composed by 4‐species increased the yield stability compared to monocultures in the 3‐year period of our study, particularly on Cambisols soil. Sward digestibility applied to average values did not differ much between sites with mixtures performing similarly to monocultures. The reason for that could have been the dynamics of sward botanical composition during study years shifted towards increased perennial ryegrass and decreased proportions of chicory in the sward as well as the observed phenomenon that the species in mixed swards progressed to successive growth stages more slowly than in pure sowing. [ABSTRACT FROM AUTHOR]

Natural soil inundation caused by frequent and intense precipitation affects carbon allocation in grassland biomass, ultimately leading to changes in soil carbon storage. Increasing forage diversity could provide resiliency to inundation of grassland. The objective was to evaluate forage and root biomass and C and N stocks in the soil particulate organic matter (POM) from pastures under recurring short‐term inundation. Three forage species combinations were evaluated in an inundated (typically lasting for a few days after heavy rain events) and a non‐inundated pasture: (1) predominantly tall‐fescue (Festuca arundinacea Schreb.); (2) mixture of cool‐season perennials composed of tall‐fescue, orchardgrass (Dactylis glomerata L.), bluegrass (Poa pratensis L.) and white (Trifolium repens L.) and red clover (Trifolium pratense L.); (3) and cool‐season mixture of perennials overseeded with oats (Avena strigosa Schreb.) and rye (Secale cereale L.). Roots and forage biomass were sampled during the growing seasons of 2021 and 2022. Soil POM was evaluated 2.5 years after establishment. Inundation reduced forage and root biomass mainly during periods of higher inundation frequency, leading to lower C‐POM stocks (p <.05). Inundation caused a shift in the forage botanical composition, that is, higher occurrence of weeds and less productive grass species with shallow roots. The perennial cool‐season mixture did not increase forage yield compared with tall fescue only but did increase root mass. This occurred mainly at deeper layers and, consequently, increased C‐POM stocks (p <.05). Overseeding of winter annuals reduced overall forage production, despite increasing spring biomass when inundated in the first year, but reduced C and N‐POM stocks (p <.05). Perennial cool‐season forage mixtures can increase the resilience of pastures to inundation events and contribute to increased carbon sequestration in grasslands where inundation is prevalent. [ABSTRACT FROM AUTHOR]

Multispecies swards, comprised of different plant functional groups have comparable production potential to high N input L. perenne swards at reduced N when legumes are included. However, information on the appropriate management of multispecies swards is limited. The effect of differing management practices on the herbage dry‐matter (DM) production and botanical composition of different sward types was investigated using a 3 × 2 × 2 factorial design plot experiment. The experiment consisted of three sward types: L. perenne‐only receiving (LP; 250 kg N ha−1 a−1); L. perenne‐Trifolium repens (LP‐TR); multispecies sward containing L. perenne, Phleum pratense, Trifolium repens, Trifolium pratense, Plantago lanceolata and Cichorium intybus (MSS). LP‐TR and MSS received 90 kg N ha−1 a−1. Harvesting of plot herbage took place every 21 or 28 days to a defoliation height of 4 or 6 cm, over two growing seasons (March to November 2020 and 2021 inclusive). Annual herbage produced by both LP and LP‐TR was not significantly affected by defoliation frequency. However, MSS produced 1923 kg DM ha−1 a−1 more herbage when harvested less frequently. Unsown species contributed significantly less to the herbage DM of MSS compared to LP and LP‐TR and remained similar in 2020 and 2021, whereas the contribution of unsown species to herbage DM increased in LP and LP‐TR from 2020 to 2021, with noxious species more associated with LP and LP‐TR than MSS. Results demonstrate the role of multispecies swards in improving the sustainability of grass‐based agricultural systems in an environment of reduced fertilizer inputs. [ABSTRACT FROM AUTHOR]

The expanded usage of white clover has increased the importance of understanding white clover dynamics in pastures. It is assumed that clover plants have a higher tolerance for moisture and nutrient deficiencies when the taproot is still present. Therefore, the survival of the seminal taproot can influence the dynamics of clover. Past breeding efforts in countries like New Zealand have focussed on increasing the taproot longevity through hybridisation with a close relative of white clover. However, there is no direct evidence whether increased survival of the taproot results in increased performance of white clover. In this study, we aimed to (i) assess the relationship between taproot volume and taproot survival, and (ii) whether the timing of death of the seminal taproot influences the population dynamics of white clover varieties. In a two‐year field experiment with 18 white clover varieties grown in monoculture and in mixture with Lolium perenne L, the taproot characteristics and population dynamics were studied. It was shown that taproot volume was positively correlated to both leaf size and taproot presence during autumn 2017, 1 year after sowing. The combination of the timing of death of the seminal tap root and the development of stolons seems to play a more important role in increasing the persistence of white clover than the absolute survival of the seminal taproot. Future research should focus on understanding the transition from a taprooted white clover to a stolonous white clover plant in relation to specific weather events such as winter frost conditions. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (PRG, Lolium perenne L.) breeding effort in New Zealand (NZ) has increased since c. 1990, resulting in greater functional trait diversity (e.g. heading date, ploidy, and associated Epichloë endophyte strain) in commercial products. This study quantified the variation, associations and interactions in dry matter (DM) yield, nutritive value and persistence‐related traits among commercial cultivar‐endophyte combinations released between 1973 and 2012, as a basis for assessing gains in value being delivered to the pasture‐based livestock industries. Twenty‐four or 28 combinations were compared over 3 years in two trials in each of two regions: Waikato in northern NZ (dryland), and Canterbury in central eastern South Island (irrigated). Cultivar‐endophyte combinations were sown in mixtures with white clover, and pastures were intensively grazed 8–11 times per year by dairy cows. Principal Component Analysis identified 4 distinct clusters for the DM yield variables and for metabolisable energy (ME) content in each of the four trials. A broadly‐adapted group of three late‐season flowering, AR37‐infected diploids with NZ and Spanish breeding backgrounds dominated the highest‐yielding clusters. Tetraploids dominated the high ME content clusters. Interactions with region were observed throughout the data set: the strongest of these was driven by endophyte strain effects in Waikato. High‐yielding cultivar‐endophyte combinations in these trials were also generally high‐yielding in the standard cultivar merit testing system operated in New Zealand, as interpreted via the DairyNZ Forage Value Index. However, alignment was poorer for medium‐ and lower‐yielding cultivar‐endophyte combinations. Several implications for forage evaluation methods and end‐user industries are identified. [ABSTRACT FROM AUTHOR]

Forage legumes such as white and red clover improve the nutritional quality of grazed pasture but can cause bloat. Their rapid fermentation in the rumen also contributes to environmental issues through higher methane emissions and urinary nitrogen losses. Condensed tannins are known to reduce urinary nitrogen and methane production from grazing animals, reduce bloat, reduce internal parasite burden, and improve animal productivity. Several forage legumes including birdsfoot trefoil and sainfoin do have good levels of condensed tannins but unfortunately these species fail to persist in intensively grazed pasture systems. Conventional breeding approaches including mutagenesis and phenotypic selection have failed to deliver condensed tannins in legumes, such as white clover, red clover or lucerne, that do persist under grazing. A recent advance using a molecular biology approach has identified a transcription factor or master switch that can 'turn on' the condensed tannin pathway present in white clover allowing biologically significant levels of condensed tannin expression in leaf tissue. In vitro tests have demonstrated that the condensed tannins produced in white clover leaves can bind protein at a pH 6.5, as found in the rumen, and then release them at pH 2.5, the pH in the abomasum, before entering the small intestine for amino acid absorption. Additional tests have demonstrated that these condensed tannins can reduce methane production by up to 15.7% in the first 6 h of incubation. The journey to this point, and the challenges ahead to deliver white clover cultivars with condensed tannin expression, is described. [ABSTRACT FROM AUTHOR]

In the rain‐fed mixed‐farming systems of southern Australia, the consistent supply of high‐value forage is limited by a range of climatic, edaphic and systems constraints. Over 2 years, we compared biomass production and nutritional value of 30 accessions of perennial legumes, and predicted intake, grazing days and growth of ewes and lambs. There was significant variation in nutritional value and biomass production between and within species. Lucerne (Medicago sativa) and sulla (Hedysarum coronarium) produced the greatest amount of biomass and energy. There was variability among accessions in digestibility (DMD), acid detergent fibre (ADF) and crude protein, and the rate of change in these traits as plants matured. Trifolium species had the highest DMD across all growth stages. Hairy canary clover (Dorycnium hirsutum), erect canary clover (Dorycnium rectum), greater birdsfoot trefoil (Lotus uliginosus), Australian trefoil (Lotus australis) and running postman (Kennedia prostrata) had energy levels that would not maintain liveweight of mature sheep. In the second year, species differed in response to harvesting treatments. Lucerne and sainfoin (Onobrychis viciifolia) were more productive under a frequent cutting regime. Accessions of white clover (Trifolium repens), red clover (Trifolium pratense), alsike clover (Trifolium hybridum), cullen (Cullen australasicum), strawberry clover (Trifolium fragiferum), sainfoin and birdsfoot trefoil (Lotus corniculatus) showed some promise, while Tedera (Bituminaria bituminosa) and milkvetch (Astragalus cicer) performed poorly under the experimental conditions. We conclude by discussing additional agronomic and nutritional factors that need consideration when developing novel perennial legumes for mixed‐farming systems in the context of a changing climate. [ABSTRACT FROM AUTHOR]

Pasture legumes that persist under challenging agroecological conditions are crucial to ensure high lamb growth rates in dryland pastures. Pasture and lamb production from binary and diverse mixtures (Mix) of tall fescue (TF) with white clover (Whc), balansa clover (Bc), subterranean clover (Sc) and birdsfoot trefoil (Bft) were compared in a summer‐dry hill site in Corvallis, Oregon over a two‐year period. In 2018, all pasture combinations provided similar lamb liveweight gains (LWG, mean 177 g/day) in the first half of spring. Lambs in TF‐Bc and TF‐Mix pastures grew 31 to 41 g/day faster than those grazing TF‐Sc, TF‐Whc and TF‐Bft in the second half of spring (p <.05). Overall, TF‐Bc and TF‐Mix had higher (p <.05) legume contents (32% and 37% respectively) compared to other pasture combinations. In spring 2019, lambs that grazed the TF‐Mix and TF‐Whc pastures had higher LWG than those on other pastures (p <.05). The superior lamb growth rates were associated with the higher legume content and pasture quality maintained into the late spring period. Overall, the legume content of all pastures decreased over the course of the two‐year trial, with the decline being substantial for balansa clover. The present study confirmed that a high legume content of pastures leads to greater lamb growth rates. Total annual yields of pastures that had greater legume contents were superior to others (p <.05). Thus, a combination of self‐regenerating annual clovers with perennial legumes in pasture mixtures may ensure a higher legume content and longer persistence in dryland hill pastures. [ABSTRACT FROM AUTHOR]

We studied the performance of different seed mixtures and the influence of liming on the establishment of a montane pasture under acidic site conditions during a wood‐pasture separation process from 1998 to 2001 in Styria, Austria. Two treatments (with and without liming) were established, each with four seeding treatments (without seeding, commercial, site‐adapted and site‐specific mixtures), and all plots were regularly fertilized from 1998 to 2002. Vegetation surveys and forage analyses regarding development of vegetation cover, seeded species persistence, quality and yield parameters were conducted again in 2014 and 2016; soil samples were taken in 2015. After cessation of regular fertilization, the analysed soil parameters declined to levels that were sufficient or low for grasslands. pH decreased again over time, but still was significantly higher (p =.0034) in the liming treatment. The single liming during experimental set‐up also caused better long‐term performance for nearly all vegetation, quality and yield parameters. The site‐specific seed mixture performed best regarding most analysed parameters, under both liming treatments. Concerning seeded species, the habitat‐typical species Agrostis capillaris, Festuca rubra agg. and Trifolium repens persisted best with and without liming. All analysed vegetation and yield parameters stayed far behind their results of 2001 and their potential. The use of site‐specific seed mixtures supports the establishment of productive grassland on specific locations. The long‐term results also illustrated that even low‐input management like liming in multi‐annual intervals can help to improve acidic site and growing conditions significantly and thereby increases the sustainability of cost‐intensive wood‐pasture separation processes under similar conditions. [ABSTRACT FROM AUTHOR]

Dry matter (DM) production of multispecies swards compared to perennial ryegrass (Lolium perenne; PRG) swards under intensive grazing warrants investigation as it is relatively unknown. A 5 × 2 factorial experiment, with five sward types and two defoliation methods, was used to investigate the effect of grazing versus cutting on dry matter (DM) production of multispecies and PRG‐only swards. Five sward types were established namely: a PRG‐only sward, receiving 250 kg N ha−1 year−1 (PRG250), and a PRG‐only sward (PRG90), a two‐species sward with PRG and white clover (Trifolium repens; PRGWC), a six‐species sward (6S) and a nine‐species sward (9S), each receiving 90 kg N ha−1 year−1. Cutting plots measured 1.95 × 10 m and grazing plots measured 10 × 10 m. All plots were harvested concurrently every 21–30 days from April‐November for two years (2015 and 2016). A strip from the grazing plots was cut for DM yield determination prior to turning in cattle for grazing. There was an interaction between sward type and defoliation method (p < .01), whereby there was no effect of defoliation method on the PRG‐only swards, however, the annual DM production of PRGWC, 6S and 9S swards reduced under grazing compared to cutting (p < .001; on average 1,929 kg DM/ha lower). Multispecies swards had lower DM production under grazing compared to cutting, while the DM yield of PRG‐only swards was unaffected by defoliation method. [ABSTRACT FROM AUTHOR]

In grazed agricultural systems, animal urine patches are the major source of nitrogen (N) leaching losses and can cause a decline in water quality. Urine‐N rates often exceed plant requirements, and there is a need for mitigation options to reduce the impact of agriculture on the environment. One approach is to use alternative forages to reduce urine‐N loading rates, or to increase N uptake. This study used lysimeters to determine the N leaching losses, dry matter yields and N uptake following ruminant urine application to an Italian ryegrass‐plantain‐white clover forage mix (IRPWC, Lolium multiflorum Lam.‐Plantago lanceolata L.‐Trifolium repens L.) or perennial ryegrass‐white clover (PRWC, Lolium perenne L.‐T. repens L.). Three urine treatments were applied: Control (no urine), Urine Actual (urine from cows grazing each of the forages: 508, and 664 kg N/ha, for IRPWC and PRWC, respectively) and Urine 700 (700 kg N/ha). Compared with PRWC (113 kg N/ha), N leaching losses were 88.9% lower from IRPWC‐Urine Actual (12.5 kg N/ha) and 45.5% lower from IRPWC‐Urine 700 (61.8 kg N/ha). These reductions were attributed partly to the IRPWC having higher cool season activity and ability to take up N during the cool period, and partly to the lower concentration of urine‐N, compared with PRWC. IRPWC is a promising alternative forage for future farm systems with the ability to reduce urine‐N excretion from grazing animals and cause large reductions in N leaching losses while producing the same herbage dry matter yields as PRWC. [ABSTRACT FROM AUTHOR]

Increasing herbage dry‐matter (DM) production and utilization on‐farm improves efficiency and sustainability. The objective of this study was to investigate the effect of perennial ryegrass, Lolium perenne L., ploidy and white clover, Trifolium repens L., inclusion on herbage DM production and utilization in an intensive animal grazing system, with high nitrogen (N) inputs (250 kg N ha−1) and a high stocking rate (2.75 livestock units ha−1). The study was a 2 × 2 factorial design, consisting of diploid and tetraploid cultivars sown as grass‐only and grass‐white clover to give four sward treatments (diploid‐only, tetraploid‐only, diploid‐white clover, tetraploid‐white clover). These were evaluated at each grazing occasion (8–10 per year) for 3 years (2014–2016). Tetraploid‐white and grass‐white clover swards had a lower sward density (−9 and −8 kg DM cm−1, respectively) and perennial ryegrass tiller density (−820 and −1,436 tillers m−2, respectively) leading to lower postgrazing sward heights (−0.15 and −0.41 cm, respectively), and maintained a superior nutritive value when compared with diploid‐only and grass‐only swards respectively. White clover inclusion resulted in higher productivity characterized by increased herbage DM production (+1,468 kg DM ha−1), improved nutritive value and increased utilization across the three grazing seasons. Varying sward composition with perennial ryegrass ploidy led to improved nutritive value and favourable grazing characteristics in tetraploid swards. [ABSTRACT FROM AUTHOR]

Abstract: Timothy, red clover and white clover from two cuts and two stages of maturity and whole crops (WC) of barley, wheat and maize from three stages of maturity were analysed for individual plant organic acids (OAs) before and after ensiling in mini‐silos. Total OA levels, as previously reported, were generally lower in WC (14–70 g/kg dry matter) in comparison with leys (51–98 g/kg dry matter). Succinic, shikimic and fumaric acid levels were very low in all samples, while quinic, malonic, malic and citric acid constituted >90% of total OAs in all samples except maize. Maize had lower total OA levels than any other species but was the only one containing detectable levels of oxalic and aconitic acid. The sum of oxalic and aconitic acid decreased, however, from 89% to 35% of total OAs from early to late maturity, while there was a parallel increase in citric acid with increasing harvest date. Total OA level was unaffected in the ley crops by maturity, cut and species (p > .1), but among WC, wheat was higher than maize (p < .05) and also higher at early, than late maturity (p < .01). Silage total OA levels were lower than in parent crops (p < .001). Individual OA levels decreased by 38%–56% from ensiling, except for oxalic acid, which was unaffected, and succinic acid, which increased >7‐fold. Excluding succinic acid, which is also a fermentation product, average loss during ensiling was 44%. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the associative effects between fresh perennial ryegrass and fresh white clover on intake and digestion in sheep. Five proportions of ryegrass and white clover, ranging from 0 to 1 in 0·25 increments ( DM basis), were allocated to two groups of five sheep according to a replicated 5 × 5 Latin square design, and intake behaviour and digestive parameters including methane ( CH4) emissions were measured. Feeding behaviour was affected through increased forage intake when the proportion of white clover was increased, and there were positive associative effects on intake, eating time and eating rate during the main meals consumed immediately after feed was given. These effects seemed to be related to a greater motivation to eat, rather to more efficient digestion, as no difference on DM digestibility (average 766 g kg−1) was detected. There were no differences in CH4 yield (average 18·1 g kg−1 DM intake) among the treatments. The optimal proportion of white clover fed with ryegrass to optimize intake and digestion was between 0·25 and 0·50. These results indicate that mixing perennial ryegrass and white clover positively affects forage intake in sheep and their motivation to eat. [ABSTRACT FROM AUTHOR]

In grass-legume swards, biologically fixed nitrogen ( N) from the legume can support the N requirements of the grass, but legume N fixation is suppressed by additional fertilizer N application. This study sought to identify a fertilizer N application rate that maximizes herbage and N yields, N fixation and apparent N transfer from white clover to companion grasses under intensive grazing at a site with high soil-N status. During a 3-year period (2011-2013), swards of perennial ryegrass and of perennial ryegrass-white clover, receiving up to 240 kg N ha−1 year−1, were compared using isotope dilution and N-difference methods. The presence of white clover increased herbage and N yields by 12-44% and 26-72%, respectively. Applications of N fertilizer reduced sward white clover content, but the effect was less at below 120 kg N ha−1. The proportion of N derived from the atmospheric N fixation was 25-70%. Nitrogen fixation ranged from 25 to 142 kg N ha−1 measured using the isotope dilution method in 2012 and from 52 to 291 kg N ha−1 using the N-difference method across all years. Fertilizer N application reduced the percentage and yield of fixed N. Transfer of N from white clover to grass was not confirmed, but there was an increased N content in grass and soil- N levels. Under intensive grazing, the maximum applied N rate that optimized herbage and N yields with minimal effect on white clover content and fixation rates was 60-120 kg N ha−1. [ABSTRACT FROM AUTHOR]

Selective grazing of white clover ( Trifolium repens) over grass species in temperate pastures results in reduced clover abundance and availability over time. Within sheep- and cattle-grazed dryland (<800 mm annual rainfall) hill and high country areas of New Zealand, naturalized unsown annual clover species show greater persistence and abundance over sown clovers. With a view to understanding legume abundance in these areas, Merino sheep grazing preference was investigated for pure swards of naturalized species Trifolium dubium, T. glomeratum, T. arvense and T. striatum and commonly sown species T. repens and T. subterraneum. The Chesson- Manly preference index was used to explore the hypothesis that grazing preference differs between these species and changes as plants mature. Herbage offtake was quantified at vegetative (mid-late spring; November) and reproductive (early summer; December) stages of plant maturity. Significant preference distinctions between species ( P < 0·05) occurred in December, with relative preference ranging from 0·248 for T. repens to 0·065 for T. dubium. Reduced relative preference for naturalized species was related to decreasing nutritive value from spring to summer, reflecting increased stem and flower sward content. Relative preference was negatively related to increasing acid detergent fibre and neutral detergent fibre and positively related to greater crude protein and dry-matter digestibility. Naturalized annual clover species of lower grazing preference at reproductive maturity will benefit pasture sustainability via herbage and seed production and associated nitrogen-fixation inputs. [ABSTRACT FROM AUTHOR]

Utilization of long-chain alcohols ( LCOH) as diet-composition markers in sheep consuming six diets composed of improved pasture species ( Lolium perenne and Trifolium repens) with heather-gorse components ( Erica spp., Calluna vulgaris and Ulex gallii) was evaluated. Twenty-four adult cross-bred sheep were housed in individual stalls. Diet composition was estimated from LCOH concentrations, combined or not with alkanes and long-chain fatty acid ( LCFA) data using least-squares procedures. Prior to calculations, faecal concentrations were corrected using mean treatment (faecal recovery 1, FR1) recoveries and mean recoveries across diets ( FR2). Estimates were compared with those obtained without faecal correction ( FR0) and known values. Large differences between plant species and plant parts were found in LCOH patterns and total LCOH concentrations. LCOH provided complementary information to that given by alkanes and LCFA. Even-chain LCOH comprised the largest fraction, representing on average 0·894 of total concentrations. Faecal recovery was incomplete and tended to increase with carbon-chain length ( CCL) in a curvilinear manner ( FR = −7·872 + 0·580 × CCL − 0·010 × CCL2; P < 0·001; r2 = 0·752). Diet composition influenced ( P < 0·001) LCOH recovery, although variability within ( CV of 9·0%) and between ( CV of 13·3%) diets was low. Accuracy of estimates was influenced ( P < 0·001) by faecal-correction method and markers used, and the best estimate was obtained combining LCOH and alkanes. Improvement in estimate accuracy can be achieved if suitable correction of LCOH faecal concentrations is performed prior to calculations. Results indicated that LCOH showed lower dependence than alkanes and LCFA on the use of accurate faecal-correction data. [ABSTRACT FROM AUTHOR]

There is increasing interest in tall fescue ( Festuca arundinacea Schreb.) in Western Europe and elsewhere, mainly because of its better drought resistance and yield potential compared with perennial ryegrass ( Lolium perenne L.). Important drawbacks of tall fescue, compared with perennial ryegrass, are its lower digestibility and voluntary intake. Mixtures of both species might combine the advantages of each, and species interactions may eventually lead to transgressive overyielding. We compared the agronomic performance of tall fescue, perennial ryegrass and tall fescue-perennial ryegrass mixtures, as pure-grass swards or in association with white clover ( Trifolium repens L.). Tall fescue-perennial ryegrass mixtures differed in the proportion and ploidy of the perennial ryegrass component. Yield, feed quality and botanical composition were measured in the 3 years after the sowing year. We found significant effects of ploidy of the ryegrass variety and of the proportion of ryegrass in the initial seed mixture on the botanical composition of the swards. Nevertheless, all swards were dominated by tall fescue at the end of the experiment. No overyielding of the mixtures compared with that of single-species swards was found, but feed quality was intermediate between that of the single-species swards. Mixed swards had better drought resistance than L. perenne and higher feeding quality than F. arundinacea swards. [ABSTRACT FROM AUTHOR]

The effects of summer-to-winter simulated grazing management factors, namely defoliation interval ( INT: 21, 42, 56 or 84 d), defoliation height ( DH: 2·7, 3·6, 5·3 or 6·0 cm) and final defoliation date ( FIN: 23 September, 4 November or 16 December) on herbage production in a grass-clover sward were studied. Treatments were imposed between July and December 2008, with all plots under common management in the following March to June 2009. The 42-d INT achieved the highest ( P < 0·001) total herbage yield at 11·00 t DM ha−1. Shorter (21 d) and longer (56-84 d) intervals reduced annual clover herbage yield and biological nitrogen fixation estimates. Lowering DH from 6·0 to 2·7 cm in the summer-to-winter period increased sward clover content and clover herbage yield through to the following June, 6 months after treatments ended. Delaying FIN from 23 September to 16 December had no significant effect on annual clover, grass or total herbage yield. Spring-summer clover herbage yield was positively correlated with spring-summer clover stolon mass ( R2 = 0·54, P < 0·001) and, to a lesser extent, light penetration through the sward in the previous winter ( R2 = 0·16, P < 0·05). A 42-d INT with low DH (2·7-3·5 cm) is therefore recommended for grass-clover swards. [ABSTRACT FROM AUTHOR]

Increasing plant species diversity in grasslands may improve productivity and stability of yields. In a field experiment, we investigated the herbage dry-matter ( DM) yield and crude protein content of two-species swards of perennial ryegrass-white clover ( Lolium perenne L.- Trifolium repens L.) and three-species swards of ryegrass-white clover with red clover ( Trifolium pratense L.). Five different managements represented cutting, grazing and combinations thereof, with different slurry fertilization treatments in 1- to 4-year-old swards. The three-species mixture out-yielded the two-species mixture in years 1 and 2. Across all 4 years, yields were 8-10% higher in cut swards. Inclusion of red clover increased the yields of clover across the 4 years by 51% without fertilizer and by 90% when fertilized. Responses to slurry fertilization were similar in both mixtures and were mainly independent of sward age. There was a complementary effect over the season and across managements. Red clover dominated in the first and third cuts; white clover dominated in the second and fourth cuts. Red clover dominated in cut swards and white clover in grazed swards. Future prospects of the inclusion of red clover in sown swards are discussed. These may include higher nitrogen-use efficiency in ruminants, increased soil fertility and improved sward flexibility to cope with changing managements. The findings also suggest positive yield effects of alternating between cutting and grazing within the season or between years. [ABSTRACT FROM AUTHOR]

α-Tocopherol and β-carotene concentrations were measured in herbage of birdsfoot trefoil (Bft), red clover (Rc), white clover (Wc), timothy (Ti) and perennial ryegrass (Pr) grown in four mixtures (Bft+Ti, Rc+Ti, Rc+Pr and Wc+Pr) in a small-plot field experiment at Foulum, Denmark, over 2 years. Plots were fertilized with cattle slurry and harvested in a four-cut system: 30 May/7 June, 5 July/12 July, 22 August/21 August and 24 October/9 October in 2005/2006. Bft was the legume with the highest α-tocopherol concentration in most harvests [86 mg kg−1 dry matter ( DM) averaged over all harvests of 2 years], whereas mean α-tocopherol concentrations in Wc and Rc were 37 and 34 mg kg−1 DM respectively. Bft and Wc had higher β-carotene concentrations than Rc when averaged over harvests and years (80, 67 and 44 mg kg−1 DM in Bft, Wc and Rc, respectively; P < 0·0001). Vitamin concentrations were similar in harvests 1-3, but in most sward treatments they were considerably higher in harvest 4. No clear differences were found between years. Averaged over years and harvests, mean α-tocopherol concentrations in timothy and perennial ryegrass were 46 and 50 mg kg−1 DM, respectively, and mean β-carotene concentrations were 54 and 62 mg kg−1 DM. In conclusion, herbage of birdsfoot trefoil generally had higher vitamin concentrations than white or red clover, but differences between the two grass species were small and inconsistent. [ABSTRACT FROM AUTHOR]

The benefits of white clover ( Trifolium repens L.) in pastures are widely recognized. However, white clover is perceived as being unreliable due to its typically low content and spatial and temporal variability in mixed (grass-legume) pastures. One solution to increase the clover proportion and quality of herbage available to grazing animals may be to spatially separate clover from grass within the same field. In a field experiment, perennial ryegrass ( Lolium perenne L.) and white clover were sown as a mixture and compared with alternating strips of ryegrass and clover (at 1·5 and 3 m widths), or in adjacent monocultures (strips of 18 m width within a 36-m-wide field). Pastures were stocked by ewes and lambs for three 10-month grazing periods. Over the 3 years of the experiment, spatial separation of grass and clover, compared with a grass-clover mixture, increased clover herbage production, although its proportion in the sward declined through time (0·49-0·54 vs 0·34 in the mixture in the first year, 0·28-0·33 vs 0·15 in the second year and 0·03-0·18 vs 0·01 in the third year). Total herbage production in the growing season in the spatially separated treatments decreased from 11384 kg DM ha−1 in the first year to 8150 kg DM ha−1 in the third year. Crude protein concentration of clover and grass components in the 18-m adjacent monoculture treatment was greater than the mixture treatment for both clover (310 vs 280 g kg−1 DM) and grass (200 vs 180 g kg−1 DM). There was no clear benefit in liveweight gain beyond the first year in response to spatially separating grass and clover into monocultures within the same field. [ABSTRACT FROM AUTHOR]

White clover can reduce fertilizer-N requirements, improve sward nutritive value and increase environmental sustainability of grazed grasslands. Results of previous experiments in glasshouse conditions and on mown plots have suggested that white clover may be more susceptible than perennial ryegrass to treading damage on wet soils. However, this phenomenon has not been investigated under actual grazing conditions. This experiment examined the effects of treading on clover content, herbage production and soil properties within three clover-based grazing systems on a wet soil in Ireland for 1 year. Treading resulted in soil compaction, as evidenced by increased soil bulk density ( P < 0·001) and reductions in the proportion of large (air-filled) soil pores ( P < 0·001). Treading reduced annual herbage production of both grass and white clover by similar amounts 0·59 and 0·45 t ha−1 respectively ( P < 0·001). Treading reduced the sward clover content in June ( P < 0·01) but had no effect on annual clover content, clover stolon mass or clover content at the end of the experiment. Therefore, there was little evidence that white clover is more susceptible to treading damage than perennial ryegrass under grazing conditions on wet soils. [ABSTRACT FROM AUTHOR]

This study compared the profitabilities of systems of dairy production based on N-fertilized grass (FN) and grass-white clover (WC) grassland and assessed sensitivity to changing fertilizer N and milk prices. Data were sourced from three system-scale studies conducted in Ireland between 2001 and 2009. Ten FN stocked between 2·0 and 2·5 livestock units (LU) ha−1 with fertilizer N input between 173 and 353 kg ha−1 were compared with eight WC stocked between 1·75 and 2·2 LU ha−1 with fertilizer N input between 79 and 105 kg ha−1. Sensitivity was confined to nine combinations of high, intermediate and low fertilizer N and milk prices. Stocking density, milk and total sales from WC were approximately 0·90 of FN. In scenarios with high fertilizer N price combined with intermediate or low milk prices, WC was more ( P < 0·05) profitable than FN. Based on milk and fertilizer N prices at the time, FN was clearly more profitable than WC between 1990 and 2005. However, with the steady increase in fertilizer N prices relative to milk price, the difference between FN and WC was less clear cut between 2006 and 2010. Projecting into the future and assuming similar trends in fertilizer N and milk prices to the last decade, this analysis indicates that WC will become an increasingly more profitable alternative to FN for pasture-based dairy production. [ABSTRACT FROM AUTHOR]

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 m m; 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. [ABSTRACT FROM AUTHOR]

As a preliminary step in testing the hypothesis that ingestion of cyanogenic glycosides in white clover ( Trifolium repens L.) may be one of the risk factors for equine grass sickness (EGS, or equine dysautonomia), the cyanogen content of clover leaves collected from fields ( n = 16) soon after an occurrence of EGS was compared with that of (i) control white clover samples ( n = 10) collected from the same fields out of the disease period and (ii) control clover samples ( n = 54) collected sequentially from three control fields. Clover samples from EGS fields were highly cyanogenic, with a median cyanide potential of 497 (range 307-1786) mg kg dry matter−1. Furthermore, clover collected from EGS fields soon after an occurrence of EGS had significantly higher concentrations of the cyanogenic glycosides linamarin and lotaustralin than control samples. While these findings indicate that horses grazing EGS fields may ingest significant quantities of cyanogenic glycosides, the design of the study does not facilitate investigation of any potential association between cyanogens and EGS. Further study is therefore required to determine whether cyanogens are a risk factor for EGS or whether these findings simply reflect variations in plant metabolism unrelated to disease pathogenesis. [ABSTRACT FROM AUTHOR]

Mountain pastures can be improved by the application of wood ash, but its effectiveness as a source of N, P and other elements requires improved management practices. Two application rates of wood ash (6 and 12 t ha−1) were tested in a 4-year trial on a low-input fertilized pasture. Ash was complemented with mineral P, and N fixation was encouraged by sowing white clover. Wood-ash application led to increased pasture yield (by 100%) and to increased proportions of white clover and ryegrass (60%), thus improving pasture feed value. N fixation by white clover, and possibly increased mineralization because of higher pH, may have compensated for lack of N in the wood ash. Addition of mineral fertilizer improved the supply of P, although incorporation of the wood ash into the soil may also have enhanced release of P from non-extractable components. High amounts of compounds containing Ca and Mg contributed to the long-term maintenance of soil reserves of these elements. Despite high inputs of K (175-350 mg kg−1) from wood ash, annual additions of K are required to counteract depletion via plant uptake and leaching. Increased Mn availability after the treatment (up to 400 mg kg−1) may limit repeated applications of wood ash, at least on poorly aerated soils. [ABSTRACT FROM AUTHOR]

White clover-grass mixtures should provide swards with a high dry matter (DM) yield with a clover proportion of at least 0·30. This study assessed the compatibility of one white clover variety selected for competitive ability (Giga) and four other large-leaved clover varieties (Aran, Espanso, Fantastico and Regal) in mown binary mixtures with each of four grass companions (cocksfoot cv. Padania, hybrid ryegrass cv. AberExcel, Italian ryegrass cv. Crema, and tall fescue cv. Magno) over 3 years in northern Italy. On average, the mixtures including Giga had at least a two-fold greater clover proportion in the total harvested DM ( P < 0·01) and contained fewer weeds ( P < 0·10) than those with other clover varieties, and also tended to have the highest total DM yields. On average, mixtures containing AberExcel had clover proportions of >0·25 but gave the lowest total DM yields, whereas those of Magno maximized total DM and had a higher proportion of clover than Padania or Crema. No clover × grass interaction was detected ( P > 0·05). The association with Giga allowed the tall fescue-based mixture to attain a clover proportion 0·331 along with a top-yielding total DM. This mixture, compared with the only one without Giga that displayed a near-sufficient clover proportion (Espanso with AberExcel), exhibited a 21·7% higher total DM ( P < 0·05) and had far fewer weeds. [ABSTRACT FROM AUTHOR]

Severe reductions in the seed yield of white clover can occur because of feeding by the white clover seed weevil Apion fulvipes and the lesser clover leaf weevil Hypera nigrirostris which together can reduce the seed yield by more than 0·50 . From 2002 to 2006 five field experiments were carried out to investigate the relationship between the density of these two weevil species and seed yield of white clover. Damage caused by the weevils was calculated as the difference in the number of weevils and the difference in seed yield between the average of insecticide-treated and untreated plots. Loss of seed yield was expressed as a proportion of the seed yield in insecticide-treated plots, which allowed for a comparison between years as yields in insecticide-treated plots varied. A multiple regression approach was chosen in which proportional loss in seed yield was the response variable and the weevils A. fulvipes and H. nigrirostris were the independent variables. Data obtained from the experiments were used to construct the following threshold model of economic damage: [ABSTRACT FROM AUTHOR]

The effect of sowing date (SD) and sowing rate of perennial ryegrass (PRG) on the establishment of Caucasian and white clovers in New Zealand was assessed. Clovers were sown in spring on 24 September (SD1) and 9 November (SD2) 1999, and in autumn on 4 February (SD3) and 31 March (SD4) 2000. On each date, clovers were sown with 0, 3, 6 or 12 kg ha−1 of PRG. Total herbage dry matter (DM) production up to 6 November 2000 was 13–16 t DM ha−1 for SD1 and SD2 when sown with 3–12 kg ha−1 of PRG, and 7–10 t DM ha−1 for sown clover monocultures. For SD3 and SD4, total herbage production was 6–9 t DM ha−1 with PRG, while total herbage production of clover monocultures was 5·4 t DM ha−1 for SD3 and 2·6 t DM ha−1 for SD4. By 6 November 2000, white clover contributed proportionately more than 0·15 of herbage mass when sown with 3–12 kg ha−1 of PRG on SD1, SD2 or SD3, but less than 0·09 when sown on SD4. The proportion of Caucasian clover never exceeded 0·09 of herbage mass in any of the swards. White clover was successfully established in spring and in autumn with 3–12 kg ha−1 of PRG provided the 15-mm soil temperature was above 14 °C. None of the combinations of Caucasian clover and PRG provided an adequate proportion of legumes during the establishment year. This unsuccessful establishment of Caucasian clover with PRG was attributed to its inability to compete for available light as a seedling due to slow leaf area expansion from secondary shoot development and a high root:shoot ratio. Alternative establishment strategies for Caucasian clover may include the use of slow establishing grasses, cover crops and temporal species separation. [ABSTRACT FROM AUTHOR]

Seedling competition for resources during establishment affects the potential success of individual species within a pasture. Germination, emergence and leaf expansion are key characteristics that contribute to the competitive ability of species. In this study, development and growth characteristics of Caucasian clover, white clover and perennial ryegrass (PRG) seedlings were quantified. A base temperature of <4°C and an optimum temperature of ∼27°C were found for development in each species. Thermal time (Tt) requirements for 75% of final germination were lower for Caucasian clover (46°C d) and white clover (40°C d) than for PRG (76°C d), but Tt requirements for 50% of final emergence were similar (∼110°C d). The phyllochron (°C d leaf−1) for primary stem leaves was slower for Caucasian clover (109°C d) than for white clover (94°C d) and PRG (101°C d). Appearance of the first PRG tiller, which indicates the initiation of secondary leaf development, occurred after 373°C d, compared with 532°C d for the first white clover stolon. Caucasian clover crown shoots did not develop until >1180°C d. Consequently, white clover and PRG had more leaves (∼15 plant−1) and faster shoot relative growth rates (∼0·062 mg mg−1 d−1) than Caucasian clover (5 leaves plant−1, 0·049 mg mg−1 d−1). [ABSTRACT FROM AUTHOR]

Nitrogen (N), accumulating in stubble, stolons and roots, is an important component in N balances in perennial ryegrass–white clover swards, and the effects of cutting frequency on the biomass of above- and below-harvest height were studied during two consecutive years. Total dry matter (DM) and total N production, and N2 fixation, were measured at two cutting frequencies imposed in the summers of two years either by cutting infrequently at monthly intervals to simulate mowing or by frequent cutting at weekly intervals to simulate grazing. Total DM production harvested was in the range of 3000–7000 kg DM ha−1 with lower DM production associated with the frequent cutting treatment, and it was significantly affected by the different weather conditions in the two years. The higher cutting frequency also reduced the biomass below harvest height but the different weather conditions between years had less effect on stubble and, in particular, biomass of roots. The biomass of roots of white clover was significantly lower than that of roots of perennial ryegrass and remained at a relatively constant level (200–500 kg DM ha−1) throughout the experiment, whereas the biomass of perennial ryegrass roots increased from 2400 kg DM ha−1 in the year of establishment to 10 200 kg DM ha−1 in the infrequent cutting treatment and 6650 kg DM ha−1 in the frequent cutting treatment by the end of the experiment, giving shoot:root ratios of 4·7–16·6 and 0·5–1·6 for white clover and perennial ryegrass respectively. Annual N2 fixation was in the range of 28–214 kg N ha−1, and the proportion of N fixed in stolons and roots was on average 0·28. However, as weather conditions affect the harvested DM production and the shoot:root ratio, care must be taken when estimating total N2 fixation based on an assumed or fixed shoot:root ratio. [ABSTRACT FROM AUTHOR]

Factors reducing yield of organic white clover seed production were investigated in Denmark. In thirty-six fields from different regions, density of flower heads, and weevils of the genera Apion and Hypera, hatching from flower heads, were assessed. In fifteen of these fields, additional measurements were made in order to calculate potential yield and yield-reducing factors. Flower heads had a mean of ninety-two florets per head, of which proportionately 0·59 were intact, 0·08 were not pollinated and 0·34 damaged by weevils; 0·16 of the florets contained larvae of Apion species. In intact florets the mean number of seeds was 3·6. Density and size of flower heads were correlated with low density of flower heads leading to significantly more florets per head. The number of seeds per intact floret was correlated with the proportion of unpollinated florets. The number of insect-damaged florets was influenced by both larvae of Apion in and the numbers of Hypera nigrirostris (Fabr.) hatched from flower heads. One larva of H. nigrirostris caused approximately ten times the damage of a larva of Apion. Densities of Apion and Hypera were influenced by location, with fields with adjacent weevil sources being most at risk. An estimate of potential seed yield showed that, even under good harvest conditions, only a small part of potential seed yield is realized and that under suboptimal harvest conditions seed loss is high. The main factors responsible for low yields in Danish organic white clover seed production were identified as unfavourable harvest conditions and weevil damage. [ABSTRACT FROM AUTHOR]

Single pugging events, which involve remoulding of the soil around the hooves of livestock during treading, of moderate or severe pugging intensity were imposed in plots in a long-term white clover-ryegrass pasture during spring, by using dairy cows at varying stocking rates (4·5 cows 100 m−2 for 1·5 or 2·5 h respectively). Changes in the growth and morphology of white clover were investigated over the following 12 months. Defoliation at approximately 3-week intervals was carried out by mowing. Annual herbage production was reduced following moderate and severe pugging proportionately by 0·16 and 0·34 compared with the non-pugged control treatment. The corresponding decreases in white clover production were 0·09 and 0·52 respectively. Annual perennial ryegrass production was reduced by 0·37 under severe pugging. Pugging had an immediate adverse effect on growth of white clover which persisted for up to 156 d, and coincided with a large decrease in the proportion of white clover in herbage over the same period (e.g. 0·40 vs. 0·12, in control and severely pugged treatments, respectively, on day 112). In comparison, recovery in ryegrass growth was apparent after 50 d in severely pugged treatments, indicating that white clover is more vulnerable to severe pugging than perennial ryegrass. Analysis of individual white clover plants extracted from turves (300 mm × 300 mm) showed that direct hoof damage, fragmentation and burial of stolons were the major factors which reduced white clover production, rather than the changes in soil physical properties measured. Morphological characteristics associated with plant size (e.g. stolon length, growing points, and leaf numbers) all decreased under pugging. The situation had reversed by late summer, with larger plants dominating pugged plots, and coincided with the recovery of the proportion of white clover in herbage. Strategic pasture management practices, such as restricted grazing and the use of stand-off pads when soils are overly wet, are suggested as means of minimizing treading damage to pasture and reducing negative impacts on the growth and productivity of white clover. [ABSTRACT FROM AUTHOR]

Introgression of reproductive traits from the annual, profuse flowering, ball clover (Trifolium nigrescensViv.) into white clover (Trifolium repensL.) is one breeding strategy to improve seed yields ofT. repensthat must be achieved without sacrificing agronomic performance and persistency under grazing. The yield and persistency of hybrids between white clover andT. nigrescenswere compared under rotational sheep grazing over three harvest years. The hybrids included the backcross (BC) 2 and 3 generations produced using white clover as the recurrent parent. The large-leavedT. repensvariety Olwen, medium-leaved varieties AberDai and Menna and the small-leaved variety S184 were sown as controls. Hybrids and control varieties were sown with a perennial ryegrass companion; between April and the end of October in each harvest year the plots were rotationally grazed with sheep with clover and perennial ryegrass (DM) yield and the proportion of clover present measured over the growing season. The clover and total DM yields of the BC2 and BC3 were generally comparable with the small- and medium-leaved varieties within the experiment and significantly greater than the yields of the large-leaved variety Olwen. Throughout the 3 years of the experiment the BC2 maintained a clover content above 0·30 and comparable with the small-leaved varieties, while the clover content of the BC3 was comparable with the small- and medium-leaved varieties in the first and third harvest years. No significant difference in perennial ryegrass production was observed when grown with the backcrosses or the control varieties. Differences in stolon and growing-point density were observed at the end of the experiment with the density of the BC2 and BC3 less than the small-leaved variety S184 but, in common with the medium-leaved varieties, greater than the large-leaved variety Olwen. The implication of these results for the use of this material in future experiments and in the white clover breeding programme is discussed. [ABSTRACT FROM AUTHOR]

Morphology and phenology, including stolon disintegration, of white clover were studied at two sites in the first three years after sowing. The plants reached their maximum size in late summer in the first year after sowing, and the populations contained at that time mainly taprooted plants. The subsequent fragmented plants were smaller in most of the investigated characteristics. A function describing the daily transition rate from taprooted to fragmented plants in relation to daily mean temperature is presented. Deviations between the recorded and the calculated proportion of taprooted plants were small; the overall root mean square error was 0·057. The data indicated that there is a low temperature requirement that must be met prior to the onset of transition. It is also suggested that, in further modelling of the response of white clover to temperature, the effect of daylength should be accounted for, particularly if the data are collected from sites with a considerable latitudinal spread. [ABSTRACT FROM AUTHOR]

A database on the productivity of red clover (Trifolium pratense), white clover (Trifolium repens), lucerne (Medicage sativa), lotus (Lotus corniculatus) and galega (Galega orientalis) was compiled. It contains 1852 observations for 330 trials at fifty-three sites in eight north European countries for the period from 1977 to 1997. The database includes information on climatic and site characteristics, as well as agronomic data, collated into four smaller data sets. This has permitted four key agronomic issues to be examined, namely: (i) how yield for a given variety varies under different environmental conditions; (ii) how the relative performance of different species varies between sites; (iii) how persistence varies between species and sites; and (iv) what the nature of the relationship is between varieties, yield and sites within a species? Cluster analysis revealed that geographical location had a fairly strong influence on yield. Across sites for an individual variety, the cumulative day-degrees during the regrowth period had the highest correlation with total yield. In terms of the relative performance of different forage legume species across sites, red clover and lucerne were estimated to yield about 25 t DM ha' more than white clover and there was a significant impact of cumulative day-degrees during regrowth and the age of Icy on the total yield. It was found that red clover had the lowest persistence index and lucerne the highest. As regards the interaction between yield, varieties and sites, the length of growth period and the age of the ley explained two-thirds of the variation in total yield in red clover varieties of contrasting maturity types. [ABSTRACT FROM AUTHOR]

Establishing forage legumes into endophyte-infected tall fescue (Festuca arundinacae Schreb.) pastures is problematic, especially in well-established stands. A oversowing field experiment determined if this problem was because of poor nodulation. Four renovation techniques, clipped sward (treatment A), herbicided + rye seeding in the previous autumn (treatment B), herbicided in the autumn and spring (treatment C) and herbicided to suppress the sward (treatment D), were investigated to determine their effect on nodulation and root growth of lucerne (Medicago sativa L.), red clover (Trifolium pratense L.) and white clover (T, repens L.) at 16, 22 and 29 d after sowing the legumes. A pot experiment was also conducted under optimal growth conditions and using the same soil to determine the nodulation and root growth potentials of these legume species. At adequate rhizobial populations (>6 × 104 cfu g-1 soil), substantial nodulation of all species occurred by 29 d after sowing in treatments C and D, whereas nodulation of dovers was usually reduced in treatment A. Total root lengths for all sampling dates, species and treatments were severely restricted, especially under treatment A. A general correspondence of nodulation with root growth was observed for all species, with high correlations (r ≥ 085) between these variables for all legume species and treatments, suggesting that soil moisture, and possibly competition for light, were the limiting factors. These results demonstrate that weak stands of forage legumes, typically found when sown into tall fescue swards, are probably not because of inadequate nodulation. Rather, inhibition of root growth by detrimental physical! chemical conditions or allocation of limited photosynthate to shoots instead of roots is suggested. [ABSTRACT FROM AUTHOR]

The sustainability of white clover in grass/clover swards of an upland sheep system, which included silage making, was studied over 5 years for four nitrogen fertilizer rates [0 (N0), 50 (N50), 100 (N100) and 150 (N150) kg N ha−1]. A common stocking rate of 6 ewes ha−1 was used at all rates of N fertilizer with additional stocking rates at the N0 fertilizer rate of 4 ewes ha−1 and at the N150 fertilizer rate of 10 ewes ha−1. Grazed sward height was controlled, for ewes with their lambs, from spring until weaning in late summer by adjusting the proportions of the total area to be grazed in response to changes in herbage growth; surplus pasture areas were harvested for silage. Thereafter sward height was controlled on separate areas for ewes and weaned lambs. Areas of pasture continuously grazed in one year were used to make silage in the next year. For treatments N0 and N150, white clover stolon densities (s.e.m.) were 7670 (205·4) and 2296 (99·8) cm m−2, growing point densities were 4459 (148·9) and 1584 (76·0) m−2 and growing point densities per unit length of stolon were 0·71 (0·015) and 0·67 (0·026) cm−1 respectively, while grass tiller densities were 13 765 (209·1) and 18 825 (269·9) m−2 for treatments N0 and N150 respectively. White clover stolon density increased over the first year from 780 (91·7) cm m−2 and was maintained thereafter until year 5, reaching 8234 (814·3) and 2787 (570·8) cm m−2 for treatments N0 and N150 respectively. Growing point density of white clover increased on treatment N0 from 705 (123·1) m−2 to 2734 (260·7) m−2 in year 5 and it returned to the initial level on treatment N150 having peaked in the intermediate years. Stolon density of white clover was maintained when the management involved the annual interchange of continuously grazed and ensiled areas. The non-grazing period during ensiling reduced grass tiller density during the late spring and summer, when white clover has the most competitive advantage in relation to grass. The increase in stolon length of white clover in this period appears to compensate for the loss of stolon during periods when the sward is grazed and over winter when white clover is at a competitive disadvantage in relation to grass. The implications for the management of sheep systems and the sustainability of white clover are discussed. [ABSTRACT FROM AUTHOR]

A field experiment was conducted over a 4-year period to determine NO3 leaching losses from grassland on a freely draining sandy soil. The experiment consisted of all combinations of five defoliation systems; cutting-only (CO), rotational grazing (GO), mixed systems with one (MSI) or two silage cuts (MSII) plus subsequent rotational grazing, and simulated grazing (SG), four mineral nitrogen (N) application rates (0, 100, 200, and 300 kg N ha−1 year−1), and two slurry levels (0 and 20 m3 slurry ha−1 year−1). Due to the high N return by grazing animals, leaching losses in the rotational grazing systems generally were associated with NO3-N concentrations which exceeded the EU limit for drinking water. NO3 leaching losses in a rotational grazing system could be reduced by lowering the N fertilizer intensity and the inclusion of one or two silage cuts in spring. However, even in the unfertilized mixed systems, N fixation by white clover exceeded the amounts of N removed via animal products, which resulted in NO3-N concentrations well above the EU limit for drinking water. In terms of leaching losses, the cutting-only system was the most advantageous treatment. NO3 leaching losses on grassland could be predicted by the amount of soil mineral N at the end of the growing season and by the N surplus calculated from N balances at the field scale. From the results obtained a revised nitrogen fertilization policy and a reduced grazing intensity by integrating silage cuts are suggested. [ABSTRACT FROM AUTHOR]

Grassland and its management is central to the productivity of and nitrogen (N) losses from dairy farms in north-west Europe. Botanical composition, production and N surplus of grassland were assessed during five consecutive years. The experiment consisted of all combinations of five defoliation systems: cutting-only (CO), rotational grazing (GO), grazing + one (MSI) or two silage cuts (MSII) and simulated grazing (SG). Four mineral N fertilization rates (0–300 kg N ha−1 year−1) and two slurry levels (0 and 20 m3 slurry ha−1 year−1) were applied. Fertilizer N was more efficient in producing net energy (NEL) in grazing-dominated, low white clover systems (GO and MSI systems: 70 and 88 MJ NEL kg−1 N) than in white clover-rich systems (MSII, CO and SG systems: ≤60 MJ NEL kg−1 N). While sward productivity in system MSI was similar to that in system GO, system MSII benefited from increased N2 fixation at low N rates. There were small differences in NEL concentrations of the herbage between defoliation systems. Crude protein concentration of the herbage increased with increasing N supply from fertilizer, excreta and N2 fixation. N surpluses (−63 to +369 kg N ha−1 year−1) increased with increasing grazing intensity and increasing N fertilization rate. The average response in N surplus applied was 0·81, 0·59, 0·40, 0·33 and 0·24 kg N ha−1 in systems GO, MSI, MSII, CO and SG respectively. [ABSTRACT FROM AUTHOR]

Interspecific hybridization with the close relative Trifolium nigrescens Viv. (Ball clover) is a possible strategy to increase the seed yield potential of white clover ( T. repens L.). Fertile F1 plants have been used as the basis for several generations of backcrossing using T. repens as the recurrent parent. Forage quality of the parental species and backcross hybrids when grown in mixtures with perennial ryegrass ( Lolium perenne L.) was compared in field plots over three harvest years. The dry-matter digestibility (DMD) and crude protein (CP) concentration of the legume fraction was greater than that of perennial ryegrass, but the water-soluble carbohydrate (WSC) concentration of the legume components was lower than that of perennial ryegrass. Differences in forage quality between T. repens and the backcross hybrids were relatively small. The WSC concentration of the backcrosses was less than T. repens but the CP concentration was greater. Significant differences in the forage quality of the companion grass were observed when grown with the parental species and the hybrids; however, these differences were attributed to the plots with T. nigrescens and the F1 plants, where the clover content was low. Few differences in the forage quality of the grass were measured when grown with T. repens and the backcross hybrids. The impact of these results on the use of these hybrids in cultivar development programmes is discussed. [ABSTRACT FROM AUTHOR]

Abstract Two experiments were carried out to evaluate the performance of blends of three white clover (Trifolium repens L.) varieties in comparison with the component varieties and three other varieties sown individually in a mixture with perennial ryegrass (Lolium perenne L.). The plots were grazed rotationally in Experiment 1 by cattle and sheep and in Experiment 2 by sheep alone. In both experiments, the blend was composed of three medium-leaved varieties (AberDai, AberVantage and AberHerald), but with different relative contributions of the three varieties in the two experiments. Dry matter (DM) yields of white clover and perennial ryegrass were assessed in replicate plots for two years (1999 and 2000) after the establishment year. In Experiment 1, there was no significant difference between the DM yields of white clover or perennial ryegrass in either year. The decline in DM yield of white clover between years that was observed for some varieties was not found for the blend. In Experiment 2, significant differences were found in DM yields of white clover in both years. In 1999, AberDai had the highest DM yield. In 2000, AberHerald and AberVantage had the highest DM yields, and AberDai showed a decline in DM yield that was mirrored by the mean for all the white clover varieties. In both experiments, the blend did not show significantly higher DM yield than one or more of its components; indeed, in Experiment 2, it was significantly lower yielding than AberDai in 1999. However, where one component of the blend declined in DM yield between years, this was compensated for by an increase in the yield of another component. These preliminary findings suggest that the yield stability of blends may give them a potential role in agricultural practice. [ABSTRACT FROM AUTHOR]

Abstract The dry matter (DM) production of Trifolium repens , T. ambiguum and the backcross 1 (BC1) and backcross 2 (BC2) hybrids with T. repens as the recurrent parent were compared in mixtures with an intermediate heading variety of perennial ryegrass (Lolium perenne L.) under a cutting-only management over 3 harvest years. Plots of parental legume species and backcross hybrids were established from small plantlets and oversown with the companion grass. In the first harvest year, the DM yield of clover in T. repens plots was greater than that in the BC2 plots and both greater than in the BC1 plots, whilst in the second and third harvest years differences between the DM yield of clover in the T. repens and the BC1 and BC2 hybrid plots were small. Similar results were obtained for the DM yield of total herbage. There were also differences in seasonal growth in the first harvest year, when yield of clover in T. repens plots was greater than in the BC1 and BC2 hybrid plots at early cuts but not at later cuts. Few differences in seasonal growth were observed between parental species and hybrids in subsequent harvest years. Comparison of above- and below-ground biomass showed more DM in roots and rhizome of clover in the backcrosses than in the T. repens plots in the second harvest year but differences were less evident in the third harvest year. The clover in the backcross hybrid plots also had fewer stolon growing points per quadrat than the T. repens plots, but the BC2 had more than the BC1 plots. The exploitation of these hybrids in breeding programmes as a strategy to improve the persistence and drought tolerance of white clover is discussed and implications for forage production considered. [ABSTRACT FROM AUTHOR]

Abstract Infestations of pastures by species, such as creeping bentgrass (Agrostis stolonifera ), may compromise the white clover (Trifolium repens ) content in perennial ryegrass (Lolium perenne ) mixtures. However, the interactions between white clover and species other than perennial ryegrass are not well understood. Strategies to prevent creeping bentgrass infestations require an understanding of its interactions with white clover, as the exclusion of white clover from infested pastures could be the result of either direct interaction or niche-differentiation in response to management. A methodology is presented which enables the segregation of the effects of direct interaction and niche-differentiation, based on existing dry-weight-rank measurements of a number of experimental pastures, subjected to a range of management strategies. Only between the two management extremities, i.e. permanent cutting of silage and lax grazing for long periods, did niche-differentiation occur between white clover and creeping bentgrass. The white clover content was enhanced under the cutting regime, whereas lax grazing for long periods stimulated the content of creeping bentgrass. White clover was actively excluded from creeping-bentgrass-dominated patches by direct interaction, whereas it showed a high compatibility with perennial ryegrass. This direct interaction presents challenges to the prevention of creeping bentgrass by management, as creeping bentgrass and white clover showed nearly identical requirements in terms of environmental conditions and grassland management. [ABSTRACT FROM AUTHOR]

Three replicate paddocks, each of 0·235 ha, containing adjacent monocultures of perennial ryegrass or white clover [50:50 by ground area, 6 cm sward surface height (SSH) at start of experiment] were continuously stocked with three yearling and four mature non-lactating, non-pregnant Scottish halfbred ewes for 12 weeks. Herbage intake, grazing behaviour and dietary selection were measured on seven occasions. Clover SSH declined rapidly over the first 5 weeks then stabilized at 1·2–1·6 cm, whereas perennial ryegrass SSH rose slightly initially, then declined gradually. Animals initially included proportionately c . 0·6 white clover in their diet but, by the end of the experiment, this had fallen to 0·3. Total daily herbage intake declined over the 12 weeks from 1·8 kg dry matter (DM) day–1 at the start to 1·0 kg DM day–1 . Total grazing time increased from 561 min day–1 to 649 min day–1 at the end of the experiment. The results suggest that, despite overall herbage depletion and a greater depletion of white clover than perennial ryegrass as a result of the initial partial preference for white clover, the animals traded-off a reduced total intake and an increased grazing time in an attempt to maintain their initial preferred dietary composition. [ABSTRACT FROM AUTHOR]

Nine medium leaf size varieties of white clover (Trifolium repens L.) were grown in field plots with perennial ryegrass (Lolium perenne L.) variety Fennema, and yield measurements were taken under both cutting and rotational sheep grazing. The sampling and management protocols in the cut plots mirrored those for the National List testing of white clover varieties in the UK. Dry-matter yields of the white clover and perennial ryegrass components of the mixture were recorded for six cuts in each of three harvest years. White clover yields were highest under cutting, perennial ryegrass yields under grazing. Significant differences were seen between the yields of white clover varieties, and significant interactions between white clover yields and management type were also observed. This interaction effect was not seen with respect to perennial ryegrass yields. No correlation was observed between leaf size and white clover dry-matter yield under either management type. The results suggest that leaf size, on the scale of variation represented within a leaf size category, is not a good predictor of yield under rotational sheep grazing or cutting. The significance of these results for varietal evaluation and for ascertaining the underlying bases for yield differences is discussed. [ABSTRACT FROM AUTHOR]

The effect of the initial N-supplying capacity of soils (SoilN, 90–230 kg N ha–1 year–1) was tested on the dry-matter and N yields of pure or mixed white clover and perennial ryegrass swards, managed under simulated grazing over a 5-year period. The cumulated N harvested in the mixed swards was similar, both for white clover and perennial ryegrass, but the proportion of white clover showed oscillations over a 2-year period. In the first year, the SoilN effect was similar to that of fertilizer N. During the course of the experiment, the effect was always positive on the pure perennial ryegrass sward, alternately negative and nil for the white clover in the mixed sward and alternately positive and nil for the perennial ryegrass in the mixed sward; the period of these oscillations was 2 years. From the third regrowth period after sowing, the ratio between the actual N concentration and the concentration non-limiting to growth for the perennial ryegrass in the mixed sward, increased above that of the pure perennial ryegrass sward. It was in turn greater in the soils that were initially poor and then greater in those that were initially rich in soil N. The periodic oscillation of the initial SoilN effects implies that the initial SoilN gradient was alternately compensated and restored. It was concluded that N fluxes are partly responsible for the temporal oscillations in the proportion of white clover in mixed swards. [ABSTRACT FROM AUTHOR]