Livestock‐type effects on biomass and nitrogen partitioning in temperate pastures with different functional‐group abundance

Livestock grazing can be a means to maintain biodiversity in grasslands, but the outcome for vegetation structure and species composition depends on livestock type and grazing regime. This study aims at disentangling the effects of plant functional‐group abundance and livestock type on the above‐ and below‐ground biomass and N allocation in temperate pastures. We investigated the effects of cattle, sheep and mixed stocking on above‐ground biomass (AGB) and belowground biomass (BGB) and plant N pools in a replicated grazing experiment in two pasture community types with different plant functional‐group abundance (diverse vs. grass‐dominated swards). In the six treatments, AGB was reduced up to 80% compared with an ungrazed control. Cattle reduced AGB to a larger extent than sheep in diverse pastures (80 vs 44% reduction) while sheep grazing tended to do so in grass‐dominated pastures (57 vs 46% reduction); mixed stocking led to intermediate values. Grazing reduced AGB more than the N pool in AGB, thus lowering the biomass C/N ratio relative to the ungrazed control. Neither BGB nor the N pool in BGB differed between the grazing treatments and the control plots. We conclude that livestock type and functional‐group abundance are interacting factors that influence plant biomass and N pools in swards of managed temperate pastures. The contrasting biomass removal rates of cattle and sheep could be used to increase the structural heterogeneity and total plant species pool of pastures by keeping different livestock species in neighbouring patches.     

Effects of livestock breed and grazing intensity on biodiversity and production in grazing systems. 1. Nutritive value of herbage and livestock performance

Reduction of grazing intensity and the use of traditional instead of commercial breeds has frequently been recommended to meet biodiversity and production goals in sustainable grazing systems in Europe. To test the impact of such practices across a range of contrasting grassland types, integrated measurements of foraging behaviour, agronomic production and botanical, structural and invertebrate biodiversity were made over three years on four sites in the UK, Germany, France and Italy. The sites in the UK and Germany were mesotrophic grassland with high productivity and low to moderate initial levels of plant diversity, and were grazed by cattle. The French site was a semi‐natural, species‐rich grassland grazed by cattle. The Italian site contained a wider range in plant diversity, from species‐rich to mesotrophic grassland, and was grazed by sheep. The treatments were: MC, moderate grazing intensity with a commercial breed – this was designed to utilize herbage growth for optimum livestock production; LC, lenient grazing intensity with a commercial breed – this was designed to increase biodiversity by not fully utilizing herbage growth; and LT, lenient grazing intensity with a traditional breed – this was also designed to increase biodiversity. Neither fertilizers nor pesticides were applied. The nutritive value of the herbage and the performance of the livestock were measured. Mean stocking rates were proportionately 0·30–0·40 lower and mean sward heights and herbage mass on offer were 0·30–0·50 higher on the LC and LT treatments compared with the MC treatment. The proportion of live and dead material, and leaves and stems in the herbage, its chemical composition and nutritive value were little affected by the treatments. Individual livestock performance, measured as liveweight gain, showed no consistent response to treatment. In Germany, performance on the MC treatment was slightly lower than on the LC and LT treatments but no such difference was found on the sites in the other countries. Livestock breed did not have a strong effect on livestock performance. In the UK and France the traditional breeds had a lower performance but this was not the case in Germany or Italy. Livestock performance per ha of the LC and LT treatments was up to 0·40 lower than of the MC treatment. It is concluded that biodiversity‐targeted extensive grazing systems have potential to be integrated into intensive livestock production systems because the individual livestock performance reaches a similar level compared to a moderate grazing intensity. Traditional breeds did not have a production advantage over commercial breeds on extensively managed pastures.     

Grazing legumes in Europe: a review of their status, management, benefits, research needs and future prospects

In many parts of Europe there has been a net decline in the use of forage legumes since the 1980s, despite the reputed value of legumes for low‐input livestock production systems. The political environment within which livestock farming in much of Europe operates (Common Agricultural Policy) is shifting the balance of economic advantage towards legumes and away from high usage of inorganic fertilizer. This has already been found for legume and grass–legume silages when compared with grass silages with a potential economic gain for farmers averaging 137 € ha^?1, corresponding to an annual benefit for the European livestock farming sector of as much as € 1300 million. Recent literature has shown that legume‐based grazing systems have the ability to reduce environmental problems by increasing the efficiency of N use and by avoiding a high transient surplus of soil mineral N. From the perspective of livestock nutrition, when forage legumes contain moderate levels of secondary compounds, such as condensed tannins and flavonoids, they offer considerable advantages including increased efficiency of N utilization within the digestive tract, reduced incidence of bloat hazard and higher resilience to parasites. Nevertheless, these benefits are partially counterbalanced in both temperate and Mediterranean regions by difficulties in establishment, maintenance and management under grazing. To gain knowledge on mixed grass–legume pastures, further research is required on: (i) the development of sustainable systems of livestock production which can maintain sward persistence and agricultural production under environmental stress; (ii) increasing knowledge of soil–plant–animal relations for a wide range of leguminous species, and under different soil types and climatic situations; and (iii) the benefits for consumers of food produced from low‐input livestock production systems.     

Mixed‐grass prairie rhizome biomass is influenced by cattle grazing intensity

This study was conducted on a mixed‐grass prairie in south‐central North Dakota, USA, to test the effect of animal grazing on rhizome biomass. Below‐ground plant biomass samples were collected from pastures with moderate and heavy grazing by beef cattle. Because the biomass data did not meet the normality assumptions, the computer resampling method involving a nested anova was used. A reduction in rhizomes was found under heavy grazing, as compared with moderate grazing. Although rhizomes only accounted for a small fraction of total below‐ground plant biomass, our study suggested that the high rhizome density found in the moderately grazed pastures might be partly responsible for the greater potential of plant regrowth in the moderately grazed pastures than in the heavily grazed pastures on this mixed‐grass prairie.     

Effects of livestock breed and grazing intensity on grazing systems: 3. Effects on diversity of vegetation

Finding an optimal balance between livestock production and grazing impact on plant biodiversity is an important issue in the design of grazing systems. This paper describes a study of the effect of two levels of grazing intensity combined with different animal breeds on plant biodiversity and sward structural diversity of semi-natural grasslands conducted over 3 years in the United Kingdom (UK), France (F), Germany (D) and Italy (I). There were three treatments at each site: moderate grazing intensity with a commercial breed (MC), lenient grazing intensity with a commercial breed (LC) and lenient grazing intensity with a traditional breed (LT). Grazing livestock were cattle in the UK, F and D, and sheep in I. Only grazing intensity had clear effects on vegetation diversity, the effects depending on site-specific vegetation characteristics. In more diverse pastures with finer scale heterogeneity in F and I, there was little effect of the treatments. In less diverse swards with higher grass dominance and coarse-scale heterogeneity, the number of species decreased from initial levels on the lenient grazing intensity treatments (treatments LC and LT), because of increased dominance of grasses reducing the cover of other species, particularly legumes. The structural diversity of the pastures was more affected by level of grazing intensity than botanical diversity. In more diverse, semi-natural grasslands, structural heterogeneity was not affected by the treatments. In less diverse, more productive swards, structural heterogeneity decreased where large patches were initially found on the UK site, and increased where smaller patches were initially found on the D site. It is concluded that management systems to conserve diversity need to consider carefully the background environment, and that more knowledge of the mechanisms involved is needed at farm and landscape scales.     

Development of a sustainable evaluation indicator for livestock farming system on the basis of nitrogen flow: a case study on the material flow in livestock farming along with fodder crop production and grazing on abandoned paddy fields

This study was conducted to identify the differences of characteristics of nitrogen flow on the cattle fattening breeders in different types of feeding system. Targeted breeders were classified into fodder-product type and grazing type. In both types, the nitrogen flow during livestock farming was estimated based on the inputs and outputs of materials, and summarized with following three indicators: (1) Flow-Drive Indicator (FDI), indicator for the amplified nitrogen flow per unit of external commercial materials, (2) Artificial Resources Utilization Indicator (AUI), indicator for effects of the inputs of artificial resources on nitrogen flow, and (3) Sustainability Indicator (SI = FDI/AUI), indicator for sustainability of resource utilization. As the results of nitrogen flow analysis, higher average FDI value in the grazing type (2.09) than in the fodder-product type (1.90) showed that the nitrogen from external commercial materials contributed efficiently to increase the nitrogen flow in the grazing type. The average AUI value in the fodder-product type (24.27) was clearly higher than in the grazing types (1.90). It is suggested that fodder-product type was operated by higher dependency of the inputs of utilization of artificial resources. The value of SI was less than 0.2 in the fodder-product type, and it ranged from 1.00 to 1.36 in the grazing type, respectively. It was suggested that the nitrogen flow was completely different in both types of systems, and the grazing type well utilized natural process. Moreover, by comparing the AUI and SI values, it was found that the fodder-product type was operated depending on nitrogen inputs from commercial products. In contrast, the grazing type operated well utilization of nitrogen from natural resources with less input from commercial feed.     

GRAZING MANAGEMENT FOR DAIRY CATTLE

Many studies in recent years have stressed that grassland provides the greater part of the feed requirements of ruminant livestock in temperate lands, that a large proportion of this is supplied as grazing (83, 122) and that in this form it is the cheapest source of feed for ruminants (25, 38, 40). Several authors have contrasted the production estimated to be available from pasture with the much lower proportion—about 50% (74, 116)—harvested by the animal. For these reasons the efficiency of grass utilization under grazing conditions has received intensive study in the past 20 years and many of the principles of grazing management have been elucidated. Consideration of grazing management involves a study of the needs of the animals to be catered for, the sequence of grass crops which may be grown over the season, including the influence of special-purpose pastures and of fertilizer treatment on the yield and seasonal distribution of production, and the effective conservation of surplus herbage. In this review, however, attention is concentrated on the problems concerned in grazing management for the dairy cow during the main growing period of the year. The object of grazing management may be defined as 'to ensure a large supply of nutritious grazing over the growing season at a low cost and to utilize it in such a manner that physical waste of herbage and inefficient utilization by the animal are minimized and the productive capacity of the sward is maintained'. It is a complex subject, involving many interrelated factors including botanical, animal and per-acre considerations. These are briefly outlined before the available experimental data in grazing management practices are considered.     

Sodium fluorescein as an internal tracer on the location of bovine urine patches in pastures

Sodium fluorescein (SF) was evaluated and validated as an internal marker in cattle for the location of urine patches in pastures. Three trials were carried out aiming at the following: evaluating the effect of dilution and volume of application on SF fluorescence on the environment; testing dosages and duration of excretion of SF administered orally to cattle; and validating the methodology for SF use on the location of cattle urine patches in pastures. The marker was tested in beef cattle kept on pastures under three grazing systems: degraded pasture under extensive management (De), intensively managed dryland pasture with high stocking rate (Id) and intensively managed irrigated pasture with high stocking rate (Ii). Besides the localization of urination sites, the number of urinations/animal/d and the area covered by urine were also determined. The residue of SF remained fluorescent in the pasture foliage up to 34 h after urination events, allowing the location of urine patches by a black‐light flashlight. There was no difference between grazing systems in the number of urine patches/animal/d during the rainy and dry seasons. The average number of urine patches was approximately 11/animal/d. As expected, the estimated volume and area covered by urine varied according to the stocking density. The chosen SF dose (50 mg kg^?1 LW) did not adversely affect the animals when administered once daily during 2 d. However, the same SF dose administered during four consecutive days caused urinary disorder in the animal. The distribution of urine patches was spatially dependent on specific characteristics of the paddock.     

Cattle select against the invasive grass tall fescue in heterogeneous pastures managed with prescribed fire

Tall fescue (Festuca arundinacea) is a Eurasian forage grass extensively planted in the United States. However, an endophytic fungus in tall fescue, Epichloë coenophiala, causes health problems in cattle. We predicted that cattle prefer to graze alternative forages when available. We also predicted that cattle use tall fescue more intensively in recently burned areas, as fire can increase forage quality. We tested these predictions in four diverse‐forage pastures in Iowa, comparing use by cattle of tall fescue and four alternative forages (non‐fescue cool‐season grasses, native warm‐season grasses, non‐leguminous forbs and legumes) to their availabilities at the pasture scale. We also examined how tall fescue influences the distribution of grazing at a fine scale (0.1‐m² quadrats). Tall fescue was the most abundant forage (46% of plants), but composed only 26% of grazed vegetation. In contrast, legumes composed 12% of available forage but 25% of grazed vegetation. Other forages were used in proportion to availability. At a fine scale, total grazing frequency (proportion of plants grazed) was lower in quadrats containing abundant tall fescue, and higher in quadrats with abundant warm‐season grasses. Grazing frequency of tall fescue and other cool‐season grasses was greatest in recently burned quadrats, but total grazing frequency did not increase after burning. Our results show that although cattle graze tall fescue, particularly following burns, they limit their use of this grass. Given that tall fescue is underused, creates health risks for cattle, and degrades wildlife habitat quality, it may be advisable to reduce tall fescue in pastures.     

Forage availability from a temperate pasture managed with intensive rotational grazing

Successful integration of rotational grazing into livestock production systems requires estimates of pasture growth rates for feed budgeting of daily animal intake. By matching livestock nutrient demand with forage availability, over-feeding of supplements can be minimized, which reduces feed costs and the need lo manage surplus nutrients, A three-year grazing study was carried out on a Kentucky bluegrass ( Poa pratensis L.)-dominant pasture to estimate the daily quantity of herbage available to cattle in an intensive, rotational grazing system. Herbage production, species composition, and forage quality were determined in each of the six grazing cycles in a year, from April until September. The average length of a grazing cycle was 28·6 d, with 2·7 d for duration of grazing on a paddock. Pre-grazing and post-grazing sward heights, measured with a plate meter, were 14 and 7 cm, and the corresponding herbage masses were 1955 and 775 kg DM ha⁻¹ respectively. Under adequate soil moisture during 1989, herbage available for daily intake was 53 kg ha⁻¹ from April until mid- August, declining to approximately 32 kg ha⁻¹ d⁻¹ by the end of September. Distribution of this herbage was fairly uniform until the end of August. However, a dry summer in 1991 reduced herbage availability to 15 kg ha⁻¹ d⁻¹. Bluegrass and white clover ( Trifolium repens L.) formed 70% of the herbage yield during the period April–June. Later in the season, dead matter and other species increased, reducing the contribution of bluegrass and clover to approximately 60% of total dry matter. While these pastures have the potential to provide significant amounts of forage for 5–6 months in a year, additional on-farm forage reserves are needed during periods of water stress.     

Interactions between leaf lifespan and defoliation frequency in temperate and tropical pastures: a review

In continuously stocked swards or pastures the frequency at which individual tillers and individual leaves are defoliated by ruminant livestock, relative to leaf lifespan of the grass species within the sward, determines the proportion of each leaf defoliated before senescence, and hence the efficiency of harvesting of herbage. In this paper, sets of data obtained in a range of climatic conditions and with a range of grass species are used in order to document this relationship. It is shown that the frequency of defoliation of individual tillers or individual leaves is closely linked to the average stocking density used within a period of time for maintaining a steady state sward or pasture height, herbage mass or leaf area index. Consequently, any decrease in herbage growth rate should lead to a decrease in the efficiency of harvesting of herbage and then to a more than proportional decrease in total herbage consumption by ruminant livestock. These effects will be more important for grass species having short leaf lifespan than for species with long lifespan. In rotational stocking, the link between herbage growth rate and frequency of defoliation of leaves can be broken by controlling the grazing interval, so any decrease in herbage growth would not be systematically associated with a decrease in efficiency of harvesting of herbage. Rotational stocking should be more efficient than continuous stocking in low herbage production conditions, while in high herbage production systems rotational and continuous stocking would have similar efficiency. The implications of these conclusions for the management of swards and pastures to meet different objectives are discussed briefly.     

Grazing management for more resilient mixed livestock farming systems on native grasslands of southern South America

Droughts in southern South America affect grazing systems in many ways. They reduce biomass productivity; decrease livestock feed intake, weight and reproductive performance; increase farmers’ costs; and reduce farm income. It was hypothesized that simple grazing management variables affect the resilience of grazing systems to droughts at the paddock and farm scales. The effects of grazing management on herbage and animal production were assessed at paddock level, and how technological and structural variables relate to the production and economic performances at farm level. Results of a grazing experiment controlling herbage allowance at paddock level showed that resistance of herbage accumulation and animal live weight to drought was significantly higher for paddocks with higher pre‐drought herbage allowance than for those managed to low herbage allowance treatments. A strong positive linear relationship was found between pre‐drought herbage height and resistance of herbage accumulation rate (p < .01). In a longitudinal study of nine farms in Uruguay, resistance of cow pregnancy rate to drought was positively correlated with cow pregnancy rate (r = .72, p = .02) and farm net income (r = .78, p = .02), and negatively correlated with sheep‐to‐cattle ratio (r = ?.80, p = .01). These correlations suggest that farms with higher incomes and low proportions of sheep in the herd withstand drought better (in terms of pregnancy rate). Four common regional production strategies were identified that react differently when farmers face drought, and these results can aid farmers in those regions to design more resilient mixed livestock farming systems and can inform policymakers about effective strategies for mitigating drought impacts in the region.     

A review of our current understanding of parasite survival in silage and stored forages,with a focus on Fasciola hepatica metacercariae

Fasciola hepatica, the parasitic liver fluke, is a re‐emerging zoonotic infection and an important cause of morbidity and mortality in ruminant livestock worldwide. A significant animal welfare concern, fasciolosis also has a detrimental impact on food security, with the effects of sub‐clinical infection on growth rate and milk yield estimated to cost the UK cattle industry £40.4 million annually. It is understood that up to 50% of infective F. hepatica metacercariae may overwinter on pasture and remain viable to infect grazing livestock the following spring. However, the infection risk posed by feeding grass silage to livestock remains largely unknown as the majority of previous studies are outdated in both experimental design and analysis of ensiled metacercariae viability. Anecdotal reports of fasciolosis outbreaks in housed livestock have reignited interest in F. hepatica metacercariae survival during modern ensiling processes and more importantly if they retain viability within stored forages. Consequently, a comprehensive review of the available literature is required in order to identify knowledge gaps and highlight future research opportunities regarding the role of silage in the transmission of F. hepatica.     

Effect of breed of cattle and season on diet selection and defoliation of competitive plant species in semi-natural grasslands

To maintain biodiversity in semi‐natural grasslands, the choice of breed of livestock and season of grazing can be important. The objective was to determine the effects of breed and season on the composition of plant fragments in the faeces of cattle grazing a heterogeneous semi‐natural grassland. Twelve heifers of the traditional Swedish Väneko breed (live weight 309 kg) and twelve heifers of the Charolais breed (live weight 431 kg) were allocated to three pastures per breed. Faeces samples were collected in spring, summer and autumn for micro‐histological examination of plant fragments. On the same occasion, defoliation of four competitive plant species was recorded. Faecal plant fragments mainly consisted of grasses but also herbs, whereas Cyperaceae, despite their abundance on the pastures, only composed a small proportion of fragments. Season affected the composition of plant fragments in the faeces, with a higher proportion of Cyperaceae and herbs in spring than later in the grazing period (P < 0·001), and the heifers ingesting more grasses and woody plants in autumn. In spite of a clear difference in live weight between the two breeds, no effects of breed on the composition of plant fragments in faeces were observed, although Väneko heifers defoliated more Filipendula ulmaria in spring than the Charolais heifers (P < 0·01). In addition, defoliation of Alnus glutinosa increased later in the grazing period (P < 0·05), especially for the Väneko heifers, indicating control of pernicious brushwood by grazing may be more effective in autumn.     

Sward herbage accumulation and nutritive value as affected by pasture renovation strategy

Perennial ryegrass pastures are the main feed for dairy cows in temperate regions. Alternatives to increase farm sustainability such as naturalized pastures have been proposed, and only limited knowledge exists regarding their potential as a forage source for grazing dairy systems. A field study was undertaken between September 2006 and September 2009 in Valdivia, Chile, to assess the effect of three pasture renovation strategies [naturalized fertilized (NFP); cultivated fertilized Lolium perenne and Trifolium repens mixture (RGWC); and cultivated fertilized Bromus valdivianus, Dactylis glomerata, Holcus lanatus, Lolium perenne and Trifolium repens mixture (MIXED)] over a naturalized degraded pasture on herbage production, botanical change and chemical composition. The three renovation strategies increased total herbage accumulation. During 2007–2008 and 2008–2009, the naturalized fertilized pasture produced similar amounts of dry matter as the cultivated fertilized mixtures. A higher grazing efficiency (the proportion of total herbage mass accumulation, removed by grazing dairy cows) was estimated for NNFP, RGWC and MIXED. Fertilization and liming increased the proportions of Lolium perenne and Bromus spp. at the expense of Agrostis capillaris and Trifolium repens. In the cultivated mixtures, the amount of Lolium perenne tended to decrease over time. Crude protein concentration and digestibility tended to be higher for naturalized fertilized and perennial ryegrass–white clover pastures throughout the experiment. These results suggest that fertilization and liming of a low-producing naturalized pasture might be a sound alternative for pasture improvement.     

Effects of livestock breed and grazing intensity on biodiversity and production in grazing systems. 2. Diet selection

Reduction in grazing intensity and the use of traditional instead of commercial breeds have frequently been recommended to meet biodiversity and production goals in sustainable grazing systems. The impact of such practices within a range of contrasting grassland vegetation types was studied. This paper describes the effects on foraging behaviour in a study conducted over three years on mesotrophic or semi-natural grasslands in UK (steers), Germany (steers), France (heifers) and Italy (sheep). Three treatments were performed: (i) a moderate grazing intensity using a commercial breed, (ii) a more lenient grazing intensity with a commercial breed and (iii) a more lenient intensity with a traditional breed. Livestock at all sites preferentially selected bites containing legumes and forbs, and also short rather than tall vegetative patches. Grazing intensity affected not only diet consumed, largely reflecting the different availabilities of dietary components, but also some differences in diet selection. Livestock grazing the more productive mesotrophic grasslands more frequently exploited short patches of higher nutritive value, which is expected to reinforce the spatial heterogeneity of the pastures. Studies in the UK and Germany also revealed that steers showed a more pronounced selection for short patches at the lenient grazing intensity. More homogeneous grazing by livestock on the semi-natural grasslands with fine-scale heterogeneity is likely to decrease their spatial heterogeneity. There were few differences in the choices made by commercial and traditional breed livestock. North Devon steers in the UK expressed a greater selection for tall grass-forb bites than Charolais × Holstein crossbreds, whereas traditional breeds appeared slightly less selective than commercial breeds at the other three sites.     

THE PRODUCTION AND UTILIZATION OF WINTER GRASS AT VARIOUS CENTRES IN ENGLAND AND WALES, 1954–60

The performance of livestock, on winter grass was studied at eighteen sites in England and Wales from 1957 to 1960.
Beef cattle generally gained weight while grazing winter grass. They invariably did better than similar animals overwintered on the normal feeding regime of the farms concerned.
At 8 centres winter grass was utilized by dairy cows. Calculations indicated that the grass provided a valuable portion of their feed.
The general condition and health of livestock grazing winter grass were satisfactory at all centres.
Damage caused by poaching was largely prevented by controlled grazing.
The production and utilization of winter grass had no adverse effects on sward recovery in the subsequent spring.     

Impact of deferred grazing and fertilizer on herbage production,soil seed reserve and nutritive value of native pastures in steep hill country of southern Australia

Developing sustainable grazing management systems based on perennial species is critical to preventing land degradation in marginal land classes. A field study was conducted from 2002 to 2006 to identify the impacts of deferred grazing (no defoliation of pastures for a period generally from spring to autumn) and fertilizer application on herbage accumulation, soil seed reserve and nutritive value in a hill pasture in western Victoria, Australia. Three deferred grazing strategies were used: short‐term deferred grazing (no defoliation between October and January), long‐term deferred grazing (no defoliation from October to the autumn break) and optimized deferred grazing (withholding time from grazing commenced between annual grass stem elongation and seed head emergence and concluded in February/March). These treatments were applied with two fertilizer levels (with or without fertilizer at 50 kg phosphorus ha^?1 and 2000 kg lime ha^?1 applied in year 1 only) in a factorial arrangement and two additional treatments: continuous grazing (CG) and no grazing (NG) in year 1. The deferred grazing treatments on average produced herbage dry matter of 4773 kg ha^?1, the NG produced 4583 kg ha^?1 and the CG produced 3183 kg ha^?1 in year 4 (2005–06) of the experiment. Deferred grazing treatments with and without fertilizer application produced an average of 5135 and 4411 kg DM ha^?1 respectively. Averaged over 4 years, deferred grazing increased the germinable seed pool of perennial grasses by 200% and annual grasses by 50% (except optimized deferred grazing that considerably decreased the annual grass seed pool) compared with the CG. The best of the deferred grazing strategies increased the digestibility of pastures by 7% compared with the CG. The results demonstrated that deferred grazing from spring to autumn followed by rotational grazing could be an effective tool to increase herbage production and soil seed pool and improve the digestibility of native pastures in the steep hill country of southern Australia.     

Gradients in fracture force and grazing resistance across canopy layers in seven tropical grass species

In reproductive swards, stems can act as a barrier that affects the grazing behaviour of ruminant livestock. The barrier effect of stems is closely associated with both the force required to fracture the stems and the density of these stems (in combination, these make up grazing resistance), and these factors need to be considered when making predictions about the forage intake of ruminants grazing reproductive pastures. Differences in grazing resistance between sward canopy layers of different grass species are thought to affect bite dimensions, but data are scarce. In this study, we assessed the grazing resistance for three canopy layers of seven tropical grass species. Species differed significantly in grazing resistance for every canopy layer, with a general ranking order for grazing resistance, in ascending order: Cenchrus ciliaris (‘American' buffel), Digitaria milanjiana (‘Jarra’ finger grass), Setaria surgens (annual pigeon grass), Setaria sphacelata (‘Narok’ setaria), Dichanthium sericeum (Queensland bluegrass), Chloris gayana (‘Callide’ Rhodes grass). In the top canopy layer, grazing resistance did not appear to create a barrier for any of the species, but in the bottom canopy layer, it did for all species. Species also differed in the relative contribution of fracture force and density to grazing resistance. The results highlight the importance of managing the grazing systems to minimize the barrier effect of the stems, which can be done by controlling the phenological stage of the pasture and the grass species and animal size used in the system.     

The effect of grazing management on plant species richness on the Qinghai‐Tibetan Plateau

In Maqu County, Gansu Province, China, there are two types of grazing management. Under multi‐household (MH) management, grassland is jointly managed by two or more households without fences between pastures. Under single‐household (SH) management, fenced‐off parcels of grassland are used. SH management was imposed in the belief that it would alleviate grassland degradation. Comparable land parcels with similar stocking rates subject to MH and SH management were identified and surveyed to determine the species present and species density (m^?2). MH land had greater number values than SH but the differences were not significant. A further analysis indicated that the number of households using MH land influenced species richness. There was also evidence to suggest that the quality of the forage available deteriorated under SH management. It was concluded that MH grazing resulted in greater species richness than SH and is perhaps an important contributor to biodiversity conservation and grassland management for the region.