悼念绿色革命之父布劳格博士

布劳格博士从事国际农业研究65年,主要贡献包括:(1)培育的矮秆高产小麦品种为解决世界粮食问题做出了杰出贡献,被誉为绿色革命之父,他不仅是CIMMYT的创始人,也是整个国际农业研究磋商组织的创始者;(2)创立了世界粮食奖;(3)开展了以推广玉米新品种为主要内容的非洲农业革命.     

“清如玉壶冰”——怀念爷爷吴觉农的朋友、茶人何耀曾先生

何耀曾先生（1920—2010）是重庆复旦大学茶叶专修科的第一届毕业生（1944），从那时起，他为中国茶业的兴盛工作了六十多年。在他去世前的三年里，我曾多次访问他，记下了他的回忆和他与张志澄、钱梁、吴觉农先生的往来。     

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.     

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.     

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.     

Categorization of grazing systems to aid the development of land use policy in Aragon,Spain

Ruminant livestock depends primarily on forage and grazing resources from both natural pastures and from cultivated land. Low‐input large‐scale grazing systems constitute a substantial part of what is termed High Nature Value farmland in Europe. Developing a typology of categories of livestock systems within a region is an important step in understanding land uses that involve ruminant livestock systems and their use of feed resources, and in appraising policy options. This study developed a typology based on the municipalities of the region of Aragon in the north‐east of Spain on the basis of the feed resources for ruminant livestock. A clustering analysis was applied to the following three types of criteria: (i) crop types; (ii) vegetation types of uncultivated land and (iii) stocking rate of dairy cattle, beef cattle, sheep and goats. A total of thirty‐nine variables were used. The cluster methodology allowed relatively homogeneous groups of municipalities, termed territories, with differentiating characteristics to be obtained. A Geographic Information System was applied to locate spatially the territories. From the twelve territories identified, it was concluded that there was a low use of natural pastures and high use of resources of cultivated origin in livestock systems in Aragon.     

Effects of livestock breed and grazing intensity on biodiversity and production in grazing systems. 4. Effects on animal diversity

Finding an optimal balance between livestock production and grazing impact on animal diversity is important for the development of sustainable grazing systems. This paper tests the hypothesis that extensification of grazing management enhances animal diversity. Similar treatments were applied over a period of three years to sites in the UK, France, Germany and Italy. 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). Animal diversity was studied at the species level for birds, hares, butterflies and grasshoppers, and at higher taxonomic level for ground-dwelling arthropods. Bird and hare numbers were low and showed no overall treatment effects. Species richness and abundance of butterflies and grasshoppers were higher for treatment LC than for treatment MC, both for species preferring short open grasslands and those preferring tall grasslands. There was no difference in the impact of commercial or traditional breeds. Most ground-dwelling arthropod groups did not show consistent treatment effects but some taxa showed site-specific responses, generally indicating a greater abundance at lenient grazing intensity. Overall, the study showed that lenient grazing intensity enhanced animal diversity on grasslands at a small scale within 3 years. By comparison, the effect of livestock breed differences was negligible. Follow-up research is needed to elucidate the processes leading to increased biodiversity in patch mosaics and to establish the generality of these findings at larger spatial scales and longer time scales.     

A simulation model of a dairy forage system to evaluate feeding management strategies with spring rotational grazing

Abstract To counteract a decrease in the availability of grazing for feeding dairy cows in France, a simulation model is proposed in the paper, which combines decision and agronomic submodels to study forage system management strategies compatible with spring grazing use. Nine strategies were tested with the model using a sequence of 16 climatic years. Three of these strategies come from a survey in south‐west France and six others were designed with research scientists or farm advisors. The strategies differ in the duration of maize silage feeding, the area dedicated to maize silage and the area dedicated to grass silage. Results from simulation models show that the consequence of a large and constant maize silage area is a high maize silage overstock if there is an early turnout or a high grass silage overstock if turnout is late. The consequence of a low maize area is a high grazing duration combined in some years with feeding shortages. Strategies that have no feeding shortage and a low level of maize and grass silage overstock have a high grazing duration and have no constant maize or grass silage areas. The solution proposed to avoid climatic risk, and its consequences on feeding, is based on two procedures: use of reserve areas for production and allowing the production programme to be modified to take into account fresh information, especially weather records.     

Meeting the challenges of global rice production

Rice is the second most widely grown cereal crop and the staple food for more than half the world's population. More than 3 billion people consume more than 100 kg of rice per year. Rice is cultivated on 155.5 million ha with an average growth rate of 0.39% a year, in the last 30 years. In the near future, the possibility for expanding areas under rice-based systems will remain very limited because of the scarcity of global water resources for agriculture, the expansion of urban and industrial sectors in Asia where land is already limited and the high costs of developing new lands that are suited for rice production in Sub-Saharan Africa and Latin America. The average growth rate of rice yield was 3.68% per year in the early 1980s, but it has decreased to 0.74% per year in the late 1990s. Several factors may contribute to the decline of the area under cultivation and in yield growth. The most important of these factors are: limited returns as we approach the yield potential of the high yielding varieties, declining productivity in intensive rice production systems, pressures from abiotic and biotic stresses, low returns in developing countries, increasing production costs in industrialized countries, and increasing public concern for the protection of environmental resources. One of the most effective means of addressing the issues in rice cultivation and raising the average yields at the farm level is through research and subsequent dissemination of the resulting data. Rice science has made considerable progress. In the area of rice varietal improvement, recent advances in hybrid rice and the new rice for Africa (NERICA) are just two examples of the successful contributions of science to the development of rice. Research could also help reduce the gap between the potential yield obtained on experimental stations and the actual yield obtained in the fields. This could be possible by developing and promoting rice integrated crop management (RICM) systems for improving productivity and reducing the production cost per unit of output. The need for a sustainable increase in rice production affects everyone. The International Year of Rice provide us with a chance to improve food security, alleviate poverty and preserve the environment for the billions of people for whom Rice is Life. Nguu Van Nguyen About the Author. Nguu Van Nguyen earned his PhD in Agronomy in 1976 from the University of the Philippines at Los Banos (UPLB). He has been serving for 2 years as Post-Doctoral Fellow, at the International Rice Research Institute and for other two as Assistant Professor at UPLB University. He has been working from 1980 to 1993 as agronomist at IITA (International Institute of Tropical Agriculture) and at Philippine Rice Research Institute. In 1991, he began his professional career at FAO, initially as rice agronomist, in West Africa, then as agricultural officer at Crop and Grassland Service. Since 2004 he is serving as Executive Secretary, International Rice Commission.

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Aldo Ferrero About the Author. Aldo Ferrero is at present Professor of “Weed Science”, “Agronomy” and “Crop Science” and head of the “Department of Agronomy, Forest and Land Management, University of Turin (Italy). He is coordinator of the rice FAO network “Medrice”, for Europe, Mediterranean, and Middle East countries. He possesses a wide experience in the field of the weed eco-biology and weed control in rice systems. He has been co-ordinator of European research projects funded by the European Union. He currently co-ordinates the project “EU-India Rice districts network promotion through agro-economical, cross cultural, and technical actions” (RICE-NET) aimed at studying agro-economical, cultural, and historical traits of the rice cultivation in the European and Indian rice districts, in order to improve socio-economical relationships between the two geographical areas. He is referee and member of the editorial board of several international journals.

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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.     

Grasslands in ‘Old World’ and ‘New World’ Mediterranean‐climate zones: past trends,current status and future research priorities

Despite their ecological, economic and social importance, grasslands in areas with Mediterranean climates continue to receive limited scientific, political and media attention. The main objectives of this review are to compare and contrast dryland grasslands in the ‘Old World’ regions of the Mediterranean basin (southern Europe, western Asia and North Africa) with those of ‘New World’ regions with Mediterranean climates (Australia and Chile) and to identify common research priorities. The common characteristics and differences in climate, soils, native vegetation, importance of the livestock sector and the socio‐economic background for the different Mediterranean environments are examined. Past trends and the current status of temporary and permanent Mediterranean grasslands are also described. Some common issues between these regions are as follows: (i) adaptation to climate change; (ii) increasing persistence and drought survival of both annual and perennial species; (iii) the important role of forage legumes; (iv) maintaining grassland plant diversity; and (v) improved ecosystem services, such as carbon sequestration, control of soil erosion and wildfires, and preservation of both wild and domestic biodiversity. The favourable climate in these regions, which allows year‐round grazing and the growth of legumes, should be exploited to improve the sustainability of grassland‐based, extensive farming systems and the quality of their animal products, while at the same time improving ecosystem services. The decreasing support for grassland research and development programmes requires increased international scientific and technical cooperation among the few institutions operating in the different Mediterranean‐climate areas of the World to provide innovative and sustainable solutions to farmers.     

Measuring excreta patch distribution in grazed pasture through low‐cost image analysis

Nutrient losses from grazed pasture are an important non‐point source of water pollution. The distribution of animal urine patches on pasture is an important factor in determining nitrate losses and influencing pasture growth, nutritive value and pasture acceptability to livestock, as a high amount of nitrogen (N) is deposited onto a small area of soil under a urine patch. Urine distribution may be recorded during or post‐grazing. Measurements during grazing have been automated, but post‐grazing measurement currently relies on manual observations that are time consuming and cannot be subsequently verified. To automate post‐grazing measurements, aerial photographs were taken of grazed pasture approximately 14 d post‐grazing using a standard digital camera. Pasture response areas were successfully identified by analysing the hue of the images using readily available software, yielding comparable results to manual counts. The majority of dung patches did not produce observable pasture responses, with only 14% of the visible response areas being associated with dung, so although this method cannot distinguish between urine and dung response areas, it is primarily influenced by urine. Provided photographs are taken in full sunlight with a high‐quality camera, excreta patch numbers, areas and spatial distribution can be measured with a high degree of precision. Furthermore, the method is relatively inexpensive and applicable to a wide range of situations. A permanent photographic record of the pasture is also established, which allows verification of the analysis in future.     

The David Rosen lecture: biological control in citrus

David Rosen was a scientist, professor, administrator, philosopher, organizer, family man, and friend to many. He made numerous and remarkable contributions to biological control in citrus. Much of his research was on the biosystematics of Aphytis parasitoids, but he also held strong convictions about the importance of biological control in citrus integrated pest management (IPM), and carried out research on genetic improvement of parasitoids. David was the first incumbent of the Vigevani Chair of Agriculture and Professor of Entomology at the Faculty of Agricultural, Food and Environmental Quality Sciences at the Rehovot campus of the Hebrew University of Jerusalem. David served as an organizer of the XIV International Plant Protection Congress in Jerusalem, Israel, and his imprint on the congress was evident despite his absence. In addition to reviewing David's scientific contributions, I present an overview of the challenges facing biological control in the USA, including many that concerned David: increased scrutiny from regulatory agencies regarding the effects of natural enemies on nontarget species, loss of taxonomic experts, concerns about the accidental introduction of plant pathogens with the importation of natural enemies of insect vectors, and challenges to the tradition of international cooperation. If the increased demand for biological control is to be met in 21st century agricultural IPM programs, several scientific, social, and legal issues must be resolved.     

Measurement of above-ground plant biomass, forage availability and grazing impact by combining satellite image processing and field survey in a dry area of north-eastern Syria

Field survey and satellite image processing methods were used to estimate the total available forage over an area of 95 034 ha in north‐eastern Syria, and to assess grazing impact on the area. The above‐ground plant biomass was measured by a quadrat method at three sites in each of eight vegetation classes. Available forage was measured by excluding woody parts of shrubs from the whole aerial plant parts. The total above‐ground plant biomass and available forage were estimated by extrapolating the measured point data to the whole target area using classified vegetation data by satellite image processing. Grazing impact was assessed by calculating the differences between the total available forage at the end of growing season and the end of dry season. The values for the estimated total available forage (s.e. of mean) in the area were 55 628 000 (12 920 000) kg DM and 30 007 000 (2 437 000) kg DM at the end of growing season and dry season respectively. Although the area of the cereal fields covered only 0·315 of the area, about 0·69 and 0·82 of the available forage existed in the harvested cereal fields at the ends of growing season and dry season respectively. The integration of cereal fields and rangeland is a normal land use system for livestock management in the area. The higher cover of herbaceous vegetation types showed higher grazing impacts which reduced the total available forage at the end of the growing season by 0·817 (0·199) at the end of the dry season. Although these dense herbaceous vegetation types could possibly produce more available forage, they would incur more intensive grazing impact. On the contrary, lighter grazing impact would occur with a higher cover of shrub vegetation types. The importance of maintaining plant cover over the rangeland area to protect the land against soil erosion is stressed.     

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.     

“与余同是识翁人，惟有西湖波底月。”——追忆民国茶人叶知水先生

叶知水先生（1914—1947）浙江鄞县人。1939年毕业于四川大学农学院,任职于中国茶叶公司技术处。他先后在黔、浙、皖、闽、赣五省从事茶叶改良推广工作,1942年至1945年在湖南和西北调查砖茶的产销,1946年在上海营办出口茶叶精制厂,1947年5月因病去世。本文根据我采访和收集的零散资料和叶知水先生在他生命最后的八年中所发表的文章对他做一点介绍。     

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.     

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.     

Effects of continuous or rotational grazing of two perennial ryegrass varieties on the chemical composition of the herbage and the performance of finishing lambs

Plant breeding has developed perennial ryegrass varieties with increased concentrations of water‐soluble carbohydrates (WSCs) compared with conventional varieties. Water‐soluble carbohydrates are major metabolic and storage components in ryegrass. Therefore, if perennial ryegrass herbage is allowed to grow to greater heights it should contain higher water‐soluble carbohydrates concentrations, for example as under rotational grazing rather than continuous grazing by livestock. This study investigated this hypothesis and measured the performance of lambs grazed rotationally and continuously. Replicated plots of the variety AberDart (bred to express high WSC concentrations) or the variety Fennema were grazed by a core group of ten male Cheviot lambs for 10 weeks. Lambs were weighed and replicate forage samples were taken every 7 d. Concentrations of WSC in AberDart herbage were significantly (P < 0·05), but not substantially, higher than those in Fennema herbage. Rotational grazing did not increase the differential in WSC concentration between the AberDart and Fennema varieties. However, there was a tendency (P = 0·07) for lambs rotationally grazing the AberDart swards to have a higher final live weight than lambs grazing the Fennema swards. Overall, lamb performance was increased when either perennial ryegrass variety was rotationally rather than continuously grazed (P < 0·001).     

Herbage production,nutritive value and animal productivity within hardwood silvopasture,open and mixed pasture systems in Appalachia,United States

Demand for livestock food products is projected to increase dramatically through to 2050. Increased livestock production capacity on marginal lands will be critical to meeting this demand. A 5‐year research effort was undertaken to evaluate lamb and sward productivity within open and hardwood silvopasture (SP) systems in Appalachia, USA. Grazing began in mid to late April each year, with the grazing season averaging 141 d. Grazing system treatments during 2002 and 2003 grazing seasons were as follows: 100% open pasture (OP), 67% OP and 33% SP, and 67% OP and 33% SP with delayed SP grazing initiation (OSD). In 2004, a 100% SP (SP) system was added. Animals were rotationally stocked through either 6 (2002–2004) or 7 (2005–2006) paddocks. Open pasture produced greater (P < 0·001) grazing season herbage yield, while all systems generated similar animal performance. Based on summer solstice, herbage production in spring was greater (P < 0·001) than summer, except in 2003. Total non‐structural carbohydrate (TNC) content was greater (P < 0·05) in spring than in summer, except in 2004. Animal performance was superior in spring versus summer (P < 0·001). Animal plasma urea nitrogen (PUN) was lower (P < 0·05) for OP in 2003. When PUN was correlated with nutritive value indicators, the ratio of TNC to crude protein (CP) had the strongest correlation. The strong correlation indicates the need for synchronized ruminal energy and CP availability. Development of silvopasture from existing woodlots has potential to improve whole farm productivity on marginal lands.