Herbage Quality Research Articles

Concentrations of metals and metalloids in soils that have the potential to lead to exceedance of maximum limit concentrations of contaminants in food and feed

AbstractThis review focusses on the transfers of metals and metalloids from soil to food and feed, based mostly on UK information. Published information on the behaviour of a number of these contaminants in soil–plant systems is used to evaluate which elements are likely to transfer to food and feed. Data on the concentrations of metals and metalloids in soils and other soil properties in England and Wales are used in models to illustrate the likelihood of transfers exceeding the maximum concentration limits in food and feed in European legislation. Information from crop and herbage quality surveys is used to compare with the output from models. In most cases, the modelled or observed concentrations in food and feed do not reach the maximum allowable concentrations. Of all the contaminants considered, Cd appears to be most likely to exceed limit concentrations under UK conditions, but at present, there is some difficulty predicting Pb uptake and As uptake into the edible parts of crops from soil. However, crops exceeding the food limits are more likely to be grown if those crops are vegetables and if soil limit concentrations and best soil management practices have not been followed (e.g. maintenance of high soil pH in the case of cationic metals). We discuss the gaps and uncertainties for different metals and metalloids and show the need to review the situation if food or feed maximum concentration limits are changed as new information becomes available on toxicology and dietary exposure.

Above‐ and Belowground Response along Degradation Gradient in an Alpine Grassland of the Qinghai‐Tibetan Plateau

Grassland degradation is one of the worldwide ecological problems. The objective of this study was to assess the above‐ and belowground response of an alpine grassland along degradation gradient in the headwater areas of the Qinghai‐Tibetan Plateau. Results showed that aboveground biomass, cover, and high quality herbage percentage presented a decreasing trend along degradation gradient. But, species number, species diversity, and evenness showed the maximum value in moderate degraded grassland, and the minimum value was appeared in the extreme degraded grassland. Similarity index was the maximum between original vegetation and light degradation grassland. And the similarity index between light degradation and moderate degradation, between original vegetation and moderate degradation were significantly different. Meanwhile, soil hardness, pH value, soil moisture, available nitrogen, available phosphorus, and available potassium, all showed the decreased trend along the grassland degradation gradient. Grassland degradation led to a decrease of soil physics and chemical properties. Our results predicted that there was also a degradation of soil properties when community structure and composition degraded along the grassland degradation gradient.

Early season dry matter production of three hybrid ryegrass (Lolium boucheanum) and two perennial ryegrass (Lolium perenne) cultivars

Hybrid ryegrass (HRG) is purported to have high overwinter growth characteristics and may have a role in Irish grassland systems. In a 3-year small-plot study at Fermoy, Cork, Ireland, the dry matter (DM) production and herbage quality of HRG cultivars in early spring were compared with diploid and tetraploid perennial ryegrass (PRG) cultivars. Treatments comprised ryegrass cultivars × defoliation managements × defoliation heights in a 5 × 3 × 2 factorial arrangement. The cultivars were Navan (tetraploid PRG), Foxtrot (diploid PRG), Foyle (tetraploid HRG), Brutus (diploid HRG) and Belleek (tetraploid HRG). Defoliation dates were: (A) 2 February and 20 April; (B) 2 February, 3 March and 20 April; and (C): 2 February, 23 March and 20 April. Defoliation heights were 4 and 7 cm, applied across each management. The HRG cultivars yielded similarly to cv. Navan on 2 February. Cumulative spring DM production was higher in cvs. Brutus and Belleek than all other cultivars. During this period, the managements A and B had similar DM yields (2765 kg DM ha−1) but were greater than management C. Defoliating swards to 4 cm height increased DM yield compared with 7 cm height. Organic matter digestibility of grass at the silage-harvest growth stage was greater for PRG cultivars. The study indicates that early spring growth of the three HRG cultivars evaluated here was not sufficiently greater than the tetraploid PRG cv. Navan to compensate for their poorer midseason sward quality.

Effect of Digestate Application on Herbage Quality and Quantity of Permanent Grassland

Possibilities were studied for using digested substrate as fertiliser applied to grassland. Over 2008-2009, a research trial consisting of four treatments in four replicates (the non-fertilised control; sward fertilized with digested substrates from 100% slurry; 80% slurry and 20% phytomass; 60% slurry and 40% phytomass) was performed on seminatural grassland at Radvaň site. In the sward utilised by three cuts a year, these parameters were studied: botanical composition, dominant species, herbage production, organic matter and mineral substances. At the fertilized treatments, the proportion of grasses was higher in 2009 than in 2008, but that of legumes and other herbs decreased. Dominant grasses were Poa pratensis L., Festuca rubra L., Lolium perenne L., Trisetum flavescens L. while Trifolium repens L. and Medicago falcata L. dominated among legume species. The application of digested substrate as fertiliser showed positive effects on herbage production, the highest increase was found at Treatment 4 where the digested substrate consisting of 60% slurry and 40% phytomass was applied. The highest amounts of crude protein (CP), calcium (Ca) and magnesium (Mg) were recorded at the treatment with the digested substrate composed of 80% slurry and 20% phytomass applied.

Impact of grazing intensity on herbage quality, feed intake and live weight gain of sheep grazing on the steppe of Inner Mongolia

SUMMARYThe grassland steppe of Inner Mongolia is traditionally used for sheep grazing. However, overgrazing reduced vegetation cover in winter, thereby increasing soil erosion and consequently, degradation of the steppe vegetation. Grazing intensity (GI) is still the most important factor in pasture management. Hence, the aim of the current study was to evaluate the effect of GI on grassland and sheep performance. A grazing experiment was conducted from July until September in 2005, 2006 and 2007 in which six different GI ranging from very light (GI 1), light (GI 2), light-moderate (GI 3), moderate (GI 4) and heavy (GI 5) to very heavy (GI 6) were tested. Each GI treatment comprised two adjacent plots that were alternately used for grazing or hay-making each year. Variables measured included herbage mass (HM) and chemical composition, digestibility of ingested organic matter (dOM), organic matter intake (OMI) and live weight gain (LWG) of sheep. The HM decreased significantly with increasing GI from 1·01 t (GI 1) to 0·45 t dry matter (DM)/ha (GI 6). There were only minor effects of GI on chemical composition and digestibility of standing herbage. Moreover, dOM, OMI and hence, digestible OMI did not differ between GI. Across all study years, LWG of sheep was not influenced by GI so that LWG per hectare increased with increasing GI, reaching a maximum of 730 g/d at GI 6 compared with 181 g/d at GI 1. However, a strong decrease in LWG per sheep with increasing stocking rate was found in 2005 when annual rainfall was less than half of the long-term average, resulting in a similar LWG per hectare across the range of tested stocking rates. The results therefore show that intensive grazing does not reduce growth of individual animals in most years, but increases LWG per unit of land area and thus, income of farmers. The alternating use of pastures for grazing or hay-making might have mitigated the negative effects of heavy grazing on herbage and animal performance. Nevertheless, high GI may negatively affect grassland productivity in the long term and the lack of HM on offer on heavy grazed pastures in dry years will require supplement feeding at the end of the vegetation period or the untimely sale of animals.

Advanced evaluation of cowpea (Vigna unguiculata ) accessions for fodder production in the central rift valley of Ethiopia

The experiment was conducted at Adami Tulu Research Center in 2004 with 37 selected lines of grain type cowpea (Vignia species) germ-plasm introduced from Melkassa Agricultural Research Center, Lowland Pulse Improvement Program for the advanced nursery trial. Dolichos lablab (Lablab purpureius both var. Highworth and Rongai) and cowpea (Vignia ungiculata var. white worder training type) were included as a control for herbage yield and quality evaluation and ranking. The top ten accessions of cowpea (IT82D 889, TUX 1948-01F, TVU 1142 4, IT85F 2687, 82D 504-4, IT84D-448, IT93K2046-2, IT87D 551-1, IITAUK91-12, 87D -1802,) and Dolichos lablab var. Rongai was selected using the visual observation data taken during the 2004 growing season and promoted for further advanced evaluation. Advanced evaluation was carried out during the growth period, 2005 and 2006, using randomized complete block design (RCBD) of three replication of plot size 3 × 2 m. Fresh weight yield, hay yield, grain yield of both years showed statistically significant difference among accessions (p<0.005) during both growing periods. There was statistically significant difference in percentage dry matter (DM%), percentage organic matter (OM%), percentage ash (ASH%) and percentage crude protein (CP%) (P<0.0001) and the highest value of 88.94, 79.32, 12.09 and 22.3% were shown by accessions IITAUK91-12, IT87D 551-1, 87D -1802 and IT93K 2046-2, respectively. The different accessions responded to the different seasons differently based on the rainfall duration in their herbage and grain yield that needs further categorization. Key words: Adami Tulu, Dolichos lablab, herbage var. Rongai yield.

Near infrared reflectance spectroscopy (NIRS) prediction of herbage quality from forage and browse legumes, and natural pasture grass grown in Zimbabwe

Near infrared reflectance spectroscopy (NIRS) was used to predict the chemical composition of forage legumes Vigna unguiculata (cowpea), Desmodium uncinatum (Silverleaf desmodium), Stylosanthes guianensis (cv. Oxley fine stem stylo), natural pasture grass hay, Stylosanthes scabra (cv. Fitzroy) and an indigenous browse tree, Brachystegia spiciformis (Musasa). Crude protein (CP), ash, neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) were analyzed. A software for scanning, mathematical processing and statistical analysis was supplied with the spectrophotometer and used multiple linear regression (MLR). A set of 35 samples that was analyzed for calibration was selected using the software SELECT on the basis of the NIR spectra of 82 samples. The samples were scanned and screened using a FOSS NIR systems model 5000 monochromator. Equations for predicting chemical composition of the legumes were derived using scores from partial least squares (PLS) as independent variables. Cross-validation procedures indicated good correlations between laboratory values and NIRS estimates. Prediction using independent samples validated the model developed. NIRS calibrations obtained from this study could be utilized in current and future programmes of evaluating quality of forage and browse legumes for animal production. Key words: Tropical forage legumes, near infrared reflectance spectroscopy, chemical composition.

Grazing behavior and performance of beef cattle as a function of sward structure and herbage quality under rotational and continuous stocking on species‐rich upland pasture

An experiment to reveal functional response and heifers' performance to sward characteristics and forage chemical composition was conducted for 5 years in rotational (RSS) and continuous (CSS) stocking systems on native species-rich upland grassland. We measured sward characteristics, forage chemical composition, heifers' grazing behavior and live-weight gains from July to September. Mean sward surface height was lower on CSS than on RSS; grass and forb density, and white clover stolon length, were similar. Herbage on CSS had higher crude protein content and lower crude fiber content than on RSS. No difference existed in time budgets of grazing, ruminating and resting between stocking systems and season, while grazing rates were higher on CSS. Stocking rate was 1671 and 1332 kg per ha on CSS and RSS, individual daily live-weight gain 683 and 652 g on CSS and RSS. Gain per ha was 20 kg higher on CSS. Results suggested stocking systems on native species-rich grassland had no effect on activity time budgets or animal performance. Both RSS and CSS allow similar outputs for stocking rates in terms of individual daily live-weight gain. Key parameters determining heifers' behavior and performance were sward height, grass and forb density in the sward, and content of crude fiber and protein in forage.

Livestock Grazing Impacts on Herbage and Shrub Dynamics in a Mediterranean Natural Park

Shrub encroachment can be explained by the abandonment of extensive livestock farming and changes to land use, and it is a common problem in the Mediterranean mountain pastures of Europe, with direct effects on biodiversity and landscape quality. In this paper, the effects of livestock exclusion vs. grazing on the dynamics of shrub and herbaceous vegetation were analyzed in a Spanish natural park located in a dry Mediterranean mountain area over a 5-yr period. Twelve 10 × 10m exclosures were set up in six representative pasture areas of the park (with two replicates per location). Each year, the shrub number, volume, and biomass were measured in April, and the herbage height, biomass, and quality were measured in April and December (which represent the start and end of the vegetative growth season). A sustained increase of the shrub population and individual biomass was observed throughout the study, which was reflected in total shrub biomass per ha. Growth was greater in nongrazed exclosures (2 563kg dry matter [DM] · ha−1 · yr−1), but it also happened in the grazed control areas (1 173kg DM · ha−1 · yr−1), with different patterns depending on the location and shrub species. Herbage biomass did not change when grazing was maintained, but it did increase in places where grazing was excluded (291kg DM · ha−1 · yr−1), mostly as a consequence of the accumulation of dead material, with a concomitant reduction in herbage quality. It was concluded that at the current stocking rates and management regimes, grazing alone is not enough to prevent the intense dynamics of shrub encroachment, and further reductions in grazing pressure should be avoided.

Effects of rotational and continuous grazing on herbage quality, feed intake and performance of sheep on a semi-arid grassland steppe

Compared to continuous grazing (CG), rotational grazing (RG) increases herbage production and thereby the resilience of grasslands to intensive grazing. Results on feed intake and animal performance, however, are contradictory. Hence, the objective of the study was to determine the effects of RG and CG on herbage mass, digestibility of ingested organic matter (dOM), organic matter intake (OMI) and live weight gain (LWG) of sheep in the Inner Mongolian steppe, China. During June–September 2005–2008, two 2-ha plots were used for each grazing system. In RG, plots were divided into four 0.5-ha paddocks that were grazed for 10 days each at a moderate stocking rate. Instead, CG sheep grazed the whole plots throughout the entire grazing season. At the beginning of every month, dOM was estimated from faecal crude protein concentration. Faeces excretion was determined using titanium dioxide in six sheep per plot. The animals were weighed every month to determine their LWG. Across the years, herbage mass did not differ between systems (p = 0.820). However, dOM, OMI and LWG were lower in RG than in CG (p ≤ 0.005). Thus, our study showed that RG does not improve herbage growth, feed intake and performance of sheep and suggests that stocking rates rather than management system determine the ecological sustainability of pastoral livestock systems in semi-arid environments.

Foraging behavior of two cattle breeds, a whole-year study: I. Heat production, activity, and energy costs1

The foraging behavior and energy costs of activity of 19 large-frame Beefmaster × Simford (BS) cross mature cows and 14 small-frame Baladi (BA) mature cows was determined. Cows were allocated to the same paddock of a Mediterranean pasture and were monitored during 5 seasons throughout 2006 and 2007: spring (April 2006), summer (June 2006), autumn (September 2006), winter (February 2007), and early spring (March 2007). Cows were given poultry litter (25% CP, DM basis) as supplemental feed during autumn only. The cows were fitted for 3 to 4 d in each season with global positioning system (GPS) monitors, activity monitors attached to 1 of their hind legs, and heart rate (HR) monitors harnessed to their chests. Oxygen consumption per heart beat was determined for each cow during each season to enable conversion of the diurnal HR patterns to heat production (HP) units. All GPS data of cattle locations and activity and the HR and HP data were synchronized to produce simultaneous 5-min interval records; step length also was calculated for each record. These records provided summaries of partitioning among activities: lying down, standing, foraging, and walking without foraging as well as horizontal and vertical distances walked per day and number of steps taken per day. These attributes were analyzed using multiple regression models to relate these activities to HP and to estimate specific HP costs per unit of each activity. Accordingly, the daily energy costs of activity were calculated for the 2 cattle types in each season as the product of the specific activity and the number of units of each activity per day. The HP level of the large-frame BS cows was greater than that of the small-frame BA cows in winter and lower in spring (P < 0.001); however, the respective HP levels were much closer in summer and autumn, with BA cows having values greater by 3% than those of BS cows. The BA cows were more active than the BS cows during all seasons: they foraged for more hours per day (P < 0.001) and walked longer distances (P < 0.001). The mean specific costs of activity of BA cows were 20% less than those of BS cows (P < 0.001). The BA cows took longer steps during foraging and walking idle compared with BS cows despite their much smaller frame. The BA cows were more efficient in conditions of low herbage quality whereas metabolic rate of BS cows was greater in conditions of high herbage quality.

Pasture herbage mass, quality and growth in response to three whole-farmlet management systems

The effects of different whole-farm management systems were explored in a farmlet trial on the Northern Tablelands of New South Wales, Australia, between July 2000 and December 2006. The three systems examined were first, a moderate input farmlet with flexible grazing on eight paddocks considered ‘typical’ of the region (farmlet B), a second, also with flexible grazing on eight paddocks but with a high level of pasture renovation and increased soil fertility (farmlet A) and a third with the same moderate level of inputs as farmlet B but which practised intensive rotational grazing on 37 paddocks (farmlet C). The changes in herbage mass, herbage quality and pasture growth followed a seasonal pattern typical of the Northern Tablelands with generally higher levels recorded over spring–summer and lower levels in autumn–winter but with substantial differences between years due to the variable climate experienced. Over the first 18 months of the trial there were no significant differences between farmlets in total herbage mass. Although the climate was generally drier than average, the differences between farmlets in pasture herbage mass and quality became more evident over the duration of the experiment. After the farmlet treatments started to take effect, the levels of total and dead herbage mass became significantly lower on farmlet A compared with farmlets B and C. In contrast, the levels of green herbage were similar for all farmlets. Throughout most of the study period, pastures on farmlet A with its higher levels of pasture renovation and soil fertility, had significantly higher DM digestibility for both green and dead herbage components compared with pastures on either of the moderate input systems (B and C). Thus, when green herbage mass and quality were combined, farmlet A tended to have higher levels of green digestible herbage than either of the other farmlets, which had similar levels, suggesting that pasture renovation and soil fertility had more effect on the supply of quality pasture than did grazing management. This difference was observed in spite of the higher stocking rate supported by farmlet A after treatments took effect. Levels of legume herbage mass, while generally low due to the dry conditions, were significantly higher on farmlet A compared with the other two farmlets. While ground cover on farmlet A was found to be less than the other farmlets, this was largely associated with the higher level of pasture renovation. Generally, all three farmlets had ground cover levels well above 70% for the duration of the experiment, thus being above levels considered critical for prevention of erosion. A multivariate analysis showed that the main explanatory factors significantly linked (P &lt; 0.01) with the supply of high quality herbage were, in decreasing order of importance, those related to season and weather, pasture renovation, grazing management and soil fertility. Measurements of net pasture growth conducted using a limited number of grazing exclosure cages on three paddocks per farmlet revealed clear seasonal trends but no significant (P &gt; 0.05) differences between farmlets. However, post hoc estimates of potential pasture growth rate using remotely sensed MODIS satellite images of normalised difference vegetation index captured weekly from each farmlet revealed a significant (P &lt; 0.001) relationship with the seasonal pattern observed in the measurements of pasture growth rate.

Reflections on the concept, conduct and findings of the producer-led Cicerone Project

The Cicerone Project began as a producer-led partnership that sought, over a period of 8 years, to enhance the profitability and sustainability of livestock enterprises by improving the connection between those producers, research and extension. Following a detailed survey, the research and extension needs of livestock producers were identified and several applied investigations were conducted to meet those needs and delivered through a range of extension activities. This final paper of the Cicerone Special Issue reflects on the entire Project from a wide array of perspectives, including livestock producers, researchers, extension specialists and staff employed by the Project, all of whom are authors of this paper. A notable early successful outcome of the Project was the improved precision of footrot diagnosis, which has been of value to the entire sheep industry, and that flowed from a field investigation of benign and virulent footrot combined with detailed genetic investigations, which led to an improved testing regime. This paper also reflects on the findings of an unreplicated agricultural ecosystem research trial, which measured the impact of pasture renovation, increased soil fertility and grazing management on the profitability and sustainability of three different 53-ha farmlets. Valuable findings from this whole-farmlet trial included the need for a high quality feed supply for increasing stocking rate and animal liveweights; the ability and utility of satellite imagery to detect changes in pasture growth, composition and recent grazing pressure; the value of short grazing and long rest periods for controlling Barber’s pole worms of sheep; the impact of increased stocking rates on whole-farm profitability and risk; methods of optimising decisions relating to pasture renovation, fertiliser applications and grazing management; and an integrated analysis of all key measured components of the farmlet management systems. Collectively, these findings were powerful as they were demonstrated at a scale credible to livestock producers using the ‘compare – measure – learn – adopt’ approach, which was the key philosophy adopted by the Cicerone Project. By comparing and measuring different whole-farm systems, and by ensuring that producers had ownership of the trial process, the Project successfully delivered objective findings that producers trusted and which increased our understanding of important drivers of complex grazing enterprises under variable climatic conditions. Some of these drivers included: the influence of soil phosphorus on botanical composition and subsequent livestock production, the role of pasture renovation and soil fertility on herbage supply, herbage quality and stocking rate, and the improved gastrointestinal nematode control delivered by intensive rotational grazing. The beneficiaries of the Project included the 180 farmer members who participated in some 61 field days and workshops; the research and extension collaborators including four postgraduates who completed their research investigations in conjunction with the Project; and some 500 undergraduate and 300 technical students who benefited from coming to understand the applied field comparisons of the three whole-farmlet systems. Having livestock producers play a significant leadership role led to valuable outcomes achieved with research collaborators; this should encourage the development of other learning partnerships which aim to explore complex farming system issues.

Effects of three whole-farmlet management systems on Merino ewe fat scores and reproduction

As part of the Cicerone Project’s whole-farmlet experiment on the Northern Tablelands of New South Wales, Australia, the fat scores and reproductive performance of ewes were measured to assess the effect of different management systems on these important production parameters over time. The three farmlets (each of 53 ha) included one (farmlet B) subjected to ‘typical’ district management consisting of moderate levels of inputs and a target stocking rate of 7.5 dse/ha, with flexible grazing management across eight paddocks. A second farmlet (A) was managed in a similar fashion to farmlet B with respect to number of paddocks and grazing management, but modified by high rates of pasture renovation and higher levels of soil fertility, with a target stocking rate of 15 dse/ha. The third farmlet (C) was managed at the same level of moderate inputs as farmlet B but employed intensive rotational grazing over 37 paddocks and also had a high target stocking rate of 15 dse/ha. The experiment was conducted over 6.5 years from July 2000 to December 2006. In spite of the fact that target levels of stocking rate were chosen at the beginning of the experiment, stocking rate, together with fat scores and reproduction were treated as emergent properties of each farmlet system. Joining took place in April–May and lambing occurred in September–October of each year. Over the first 2 years of the experiment, there were few differences among farmlets in ewe fat scores or reproductive performance. From 2003 onwards, while the percentage of ewes pregnant was similar between farmlets, the average proportion of multiple births (ewes scanned in late July, with twins) was 30%, 16% and 12%, respectively, on farmlets A–C. However, lamb losses were greater on farmlet A, with average lamb mortalities recorded on farmlets A–C of 29%, 10% and 19%, respectively. Over the duration of the experiment, ewes on farmlets A and B were more often above a fat score level of 3, and less often below 2.5, than were ewes from farmlet C. Differences among farmlet ewes in fat score were found to be significant in 7 of the total of 13 assessments over the duration of the experiment. A generalised additive model applied to whole-farmlet data showed that green digestible herbage, legume herbage, stocking rate, the amount of supplement fed and especially the proportion of each farmlet grazed at any one time all influenced fat scores of ewes. While fat scores and conception rates tended to be highest on farmlet A, farmlet B had slightly better reproductive outcomes due to less lambing losses, whereas ewes on farmlet C tended to have somewhat lower fat scores and levels of reproduction. These farmlet-scale findings highlighted the importance for livestock managers to focus not only on grazing management, stocking rate and stock density during lambing, but also on the availability of sufficient green, and especially legume herbage, and the difficulty of overcoming a deficit in quality herbage with supplementation.

Candidate gene-based association genetics analysis of herbage quality traits in perennial ryegrass (Lolium perenne L.)

Due to the complex genetic architecture of perennial ryegrass, based on an obligate outbreeding reproductive habit, association-mapping approaches to genetic dissection offer the potential for effective identification of genetic marker–trait linkages. Associations with genes for agronomic characters, such as components of herbage nutritive quality, may then be utilised for accelerated cultivar improvement using advanced molecular breeding practices. The objective of the present study was to evaluate the presence of such associations for a broad range of candidate genes involved in pathways of cell wall biosynthesis and carbohydrate metabolism. An association-mapping panel composed from a broad range of non-domesticated and varietal sources was assembled and assessed for genome-wide sequence polymorphism. Removal of significant population structure obtained a diverse meta-population (220 genotypes) suitable for association studies. The meta-population was established with replication as a spaced-plant field trial. All plants were genotyped with a cohort of candidate gene-derived single nucleotide polymorphism (SNP) markers. Herbage samples were harvested at both vegetative and reproductive stages and were measured for a range of herbage quality traits using near infrared reflectance spectroscopy. Significant associations were identified for ~50% of the genes, accounting for small but significant components of phenotypic variance. The identities of genes with associated SNPs were largely consistent with detailed knowledge of ryegrass biology, and they are interpreted in terms of known biochemical and physiological processes. Magnitudes of effect of observed marker–trait gene association were small, indicating that future activities should focus on genome-wide association studies in order to identify the majority of causal mutations for complex traits such as forage quality.

Impact of spatial heterogeneity of plant species on herbage productivity, herbage quality and ewe and lamb performance of continuously stocked, perennial ryegrass–white clover swards

AbstractThe 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.

Effects of Non-Fertilised Grassland Management Intensity on Herbage Quality and Quantity

Effects of Non-Fertilised Grassland Management Intensity on Herbage Quality and Quantity Over 2006-2009, an optimum cutting frequency was investigated at non-fertilised grassland. The research was carried out at the Suchý vrch site (near Banská Bystrica), altitude 460 m. The research sward was utilised by cutting with different intensity: high (4 cuts), medium (3 cuts), low (2 cuts) and by 1 cut under extensive exploitation. Herbage yield, organic and mineral substances and nutritive value were determined. The intensity of sward exploitation influenced the dry matter (DM) production which was higher when utilised by two cuts than by four and three cuts, respectively. The research parameters showed the best DM quality at the highest cutting frequency (the high and the medium intensity). Crude protein (CP) content increased at higher cutting frequency, but dropped at extensive utilisation. The content of fibre was higher at less intensive cutting. The highest content of phosphorus (P) and potassium (K) was found under more intensive cutting. Towards the end of growing season, calcium (Ca) content was rising while that of K was decreasing. The sodium (Na) content was low at all the research treatments.

Herbage Quality and Animal Performance in a Coconut Cattle Inte grated System

The effect of controlled grazing on the natural herbage growing in coconut plantation on the performance of cross-bred heifers as well as on herbage yield, botanical composition and the quality were examined in an experiment for one year duration in a coconut estate at Kotawila, Kamburugamuwa. There were four treatments namely coconut without fertilizer (T1); coconut with fertilizer (CRI recommended levels) (T2); heifers grazed natural herbage (T3); and heifers grazed natural herbage with tree fodder (2 kg/d) and concentrate supplement (250 g/d) (T4). The experiment design was a RCBD with 3 replicates and the stocking rate was 2 heifers/ 0.4 ha. The daily weight gain (19.60 g/head/d) and body condition (-0.07) were poor when no feed supplements were given. Provision of tree fodder and concentrate (Gava thriposha) greatly improved the daily weight gain (28.23 g/ head/d) and body condition (0.09) of heifers. It was also observed that the season had an influence on growth and body condition.Herbage yield was higher in T2 as compared to T1 due to non grazing and fertilizer application. When compared the two treatments with animals, herbage yield of T4 were higher due to low grazing pressure imposed by supplementation. The N percentage of herbage also showed a similar trend. Over grazing without supplements (T3) would have depleted the soil and herbage N, and thereby conservation of N through recirculation within the animal. The dry period would have aggravated this condition by reducing the dung decomposition rate and increasing the urine evaporation rate. Grazing also improved the botanical composition of herbage. T3 and T4 treatments contained 55.35, 18.84 and 25.82% of grasses, legumes and other species, respectively. Herbage of T1 and T2 contained 18.5, 22.54 and 58.96% of grasses, legumes and other species, respectively. Axonopus affinus, A. compressus and Puraria phaseoloides like prostate species were dominant in T3 and T4 while Ocimum tenuiflorum and Urena lobota and Eupatorium odoratum like upland erect weed species were dominant in T1 and T2.The results show that the integrated management system based on coconut and cattle, could achieve sustain able improvements on stock performance, even within a short period of time. Actual benefits should be investi gated in the long term.

Effects of Rates and Nutrient Ratios on Production and Quality of Phytomass at Fertiliser Application to an Alluvial Meadow

Effects of Rates and Nutrient Ratios on Production and Quality of Phytomass at Fertiliser Application to an Alluvial Meadow The research objective was to assess effects of fertiliser application rates and nutrient ratios on production and quality of grassland at an alluvial meadow. The initial sward type was Festucetum pratense association. A field trial was established in the western part of "Zvolenská kotlina" basin (altitude 350 m) and consisted of ten fertiliser treatments: zero-fertilised sward (control); fertiliser P and K application; rates of 50, 100, 150 and 200 kg N/ha at two ratios of N : P : K nutrients, namely the low N : P : K ratio (1 : 0.3 : 0.8) and the high one (1 : 0.15 : 0.4), respectively. The grassland was utilised by three cuts. Dry matter (DM) production and herbage quality were determined at each of the cuts. The yield of DM was higher with the rates of 50 and 100 kg N/ha applied at the high nutrient ratio than at the low ratio. Over the research period, the highest DM production was recorded at the treatment with the low nutrient ratio and the highest N rate applied. The content of crude protein (CP) was increasing with the rising fertiliser N rate and the increase in CP was higher at the low nutrient ratio treatments. The zero-fertilised control also provided sufficient CP content. The low nutrient ratio resulted in higher P and K content than the high one. The lowest content of P and K was recorded at the control. The highest P content was found at the treatment with the fertiliser P and K applied. The highest K content was recorded at the 2nd cut, but decreased at the 3rd cut in all the treatments. The content of Ca was rising towards the 3rd cut. The content of nutrients was higher at the treatments where the high ratio was used. The content of Mg in DM was higher at the treatments with the high nutrient ratio and the high N fertiliser rates. The content of Mg was increasing in the 2nd cut at all the treatments.

Effects of N fertilisation, leaf appearance and time of day on N fractionation and chemical composition of Lolium perenne cultivars in spring

New Zealand dairy systems are based on Lolium perenne pastures with low nitrogen use efficiency (NUE) and high urinary N losses. Modelling attempts to provide solutions to improve NUE are limited due to lack of data on pasture N fractions under a range of management situations. The effects of N application (0 or 25kgN/ha), cultivar (standard and high sugar cultivars), regrowth interval (leaf appearance of 2, 3 and 4 leaf) and time of day (morning or afternoon) on chemical composition and N fractionation of L. perenne were investigated in a field study in early spring. Leaf appearance interval and time of day had the greatest influence on chemical composition and fractionation. Both fraction A (non-protein N) and water soluble carbohydrates increased by 60% between second and fourth leaf appearance (P<0.001) and by 20% between morning and afternoon (P<0.001). Total N and fractions B1 and B2 (soluble true protein) declined during the day and with leaf appearance. Addition of low fertiliser N rates did not alter N fractionation or chemical composition but improved herbage yield. The effects of using a high sugar cultivar were small and inconsistent and differences between cultivars were more closely linked with flowering date. Generally, the relative proportions of N fractions could be altered with management strategies but the overall solubility of N remained high at over 0.85. While management factors play an important role in influencing the quality of herbage and total N relative to carbohydrate, there is little scope to improve NUE by reducing the proportions of soluble N fractions.