Mariecia D. Fraser

Gains to species diversity in organically farmed fields are not propagated at the farm level

Organic farming is promoted to reduce environmental impacts of agriculture, but surprisingly little is known about its effects at the farm level, the primary unit of decision making. Here we report the effects of organic farming on species diversity at the field, farm and regional levels by sampling plants, earthworms, spiders and bees in 1470 fields of 205 randomly selected organic and nonorganic farms in twelve European and African regions. Species richness is, on average, 10.5% higher in organic than nonorganic production fields, with highest gains in intensive arable fields (around +45%). Gains to species richness are partly caused by higher organism abundance and are common in plants and bees but intermittent in earthworms and spiders. Average gains are marginal +4.6% at the farm and +3.1% at the regional level, even in intensive arable regions. Additional, targeted measures are therefore needed to fulfil the commitment of organic farming to benefit farmland biodiversity.

Grazing land management and biodiversity in the Atlantic European heathlands: a review

Atlantic heaths are semi-natural habitats of high biodiversity interest which once covered large areas of the Atlantic Region. Nowadays these heathlands are dramatically reduced in many countries although they still cover wide areas in the north-west Iberian Peninsula, especially in the poorest and most socially marginal areas that are frequently affected by wildfires. We review the role of livestock grazing as a sustainable management strategy for heathlands in Europe. We have worked on a generalized conceptual framework for the management of a resource of nutritional and environmental value by drawing together evidence from studies of the livestock and the community ecology of grazed plants and the associated fauna. Key factors that influence grazing impact, such as type of livestock (animal species and breed) and their management are discussed. Goats thrive better than sheep, and horses than cattle, when heathland vegetation is the predominant resource available. Regardless of the type of livestock species managed, the low nutritive value of this vegetation hinders the maintenance of productive groups of suckler dams with offspring through the grazing season. The nutritional requirements of livestock can be met by adding improved pasture areas to heathlands. Under that strategy, sheep have the best productive performance and cattle the poorest. Management of mixed flocks with goats can lead to a more efficient use of vegetation, improve productivity and develop a patchier habitat which supports a richer associated fauna. Overall the results indicate that the sustainability of livestock grazing in these marginal lands will be achieved if they are managed effectively according to the available vegetation and their effects on the biodiversity.

The effects of grazing forage legumes on the performance of finishing lambs

Speijers, M. H. M., Fraser, M. D., Theobald, V. J., Haresign, W. (2004). The effects of grazing forage legumes on the performance of finishing lambs. Journal of Agricultural Science, 142, (4), 483-493.

The effect of red clover formononetin content on live-weight gain, carcass characteristics and muscle equol content of finishing lambs

Moorby, J. M., Fraser, M. D., Theobald, V. J., Wood, J. D., Haresign, W. (2004). The effect of red clover formonetin content on live weight gain, carcass characteristics and muscle equol content of finishing lambs. Animal Science, 79, 303-313. Sponsorship: Meat and Livestock Commission

DETERMINING DIET COMPOSITION ON COMPLEX SWARDS USING n‐ALKANES AND LONG‐CHAIN FATTY ALCOHOLS

We conducted an experiment to quantify the accuracy of methods based on n-alkanes and long-chain fatty alcohols for determining the diet composition of animals grazing complex swards. We cut forage from two indigenous vegetation communities, a Molinia caerulea-dominated grassland and a Calluna vulgaris-dominated dwarf-shrub community, and offered it to mature ewes in different ratios in a zero-grazing experiment. Nine dietary categories were identified within the forage offered: Molinia caerulea, Festuca spp., Juncus effusus, Carex spp., Calluna vulgaris, Erica tetralix, Vaccinium myrtillus, and dead grass. Samples of each of these categories together with fecal samples from each individual animal were analyzed for n-alkane and long-chain fatty alcohol concentrations. We analyzed the data using optimization software to minimize the sum of squares differences in the proportional profiles of n-alkanes and fatty alcohols in the diet and feces. Different combinations of n-alkane and fatty alcohols were investigated to assess which gave the most accurate measures of diet composition from the fecal profile. The most accurate estimates were obtained using combinations of the n-alkanes C25, C29, C31, and C33 and the long-chain fatty alcohols 1-C24-ol, 1-C28-ol, and 1-C30-ol, and these gave values for Lins concordance correlation coefficient between estimated and actual values of >0.98. Our results demonstrate that n-alkanes and long-chain fatty alcohols can be used to estimate several components within the diet of animals grazing complex swards. Diet composition information obtained using this methodology has wide-ranging applications in terms of the assessment of the impact of grazing animals on particular ecosystems or the quantification of nutrient supply to the animal from different selection choices.

Mixed grazing systems benefit both upland biodiversity and livestock production

Background With world food demand expected to double by 2050, identifying farming systems that benefit both agricultural production and biodiversity is a fundamentally important challenge for the 21st century, but this has to be achieved in a sustainable way. Livestock grazing management directly influences both economic outputs and biodiversity on upland farms while contributing to potentially damaging greenhouse gas emissions, yet no study has attempted to address these impacts simultaneously. Methods Using a replicated, landscape-scale field experiment consisting of five management ‘systems’ we tested the effects of progressively altering elements within an upland farming system, viz i) incorporating cattle grazing into an upland sheep system, ii) integrating grazing of semi-natural rough grazing into a mixed grazing system based on improved pasture, iii) altering the stocking ratio within a mixed grazing system, and iv) replacing modern crossbred cattle with a traditional breed. We quantified the impacts on livestock productivity and numbers of birds and butterflies over four years. Results, Conclusion and Significance We found that management systems incorporating mixed grazing with cattle improve livestock productivity and reduce methane emissions relative to sheep only systems. Systems that also included semi-natural rough grazing consistently supported more species of birds and butterflies, and it was possible to incorporate bouts of summer grazing of these pastures by cattle to meet habitat management prescriptions without compromising cattle performance overall. We found no evidence that the system incorporating a cattle breed popular as a conservation grazer was any better for bird and butterfly species richness than those based on a mainstream breed, yet methane emissions from such a system were predicted to be higher. We have demonstrated that mixed upland grazing systems not only improve livestock production, but also benefit biodiversity, suggesting a ‘win-win’ solution for farmers and conservationists.

Assessment of the nutritive value of whole crop peas and intercropped pea–wheat bi-crop forages harvested at different maturity stages for ruminants

Salawu, M. B., Adesogan, A. T., Fraser, M. D., Fychan, A. R., Jones, R. (2002). Assessment of the nutritive value of whole crop peas and intercropped pea-wheat bi-crop forages harvested at different maturity stages for ruminants. Animal Feed Science and Technology, 96, (1-2), 43-53. Sponsorship: UK Milk Development Council

Diet composition of guanacos (Lama guanicoe) and sheep (Ovis aries) grazing in grassland communities typical of UK uplands

Abstract A study was undertaken to compare the diet composition of guanacos (Lama guanicoe) and sheep (Ovis aries) when pastured on improved and unimproved Agrostis spp./Festuca spp. dominated grassland typical of the UK uplands. Samples were collected from oesophageal fistulated guanacos and sheep grazing experimental plots that had been grazed previously by either sheep or guanacos. Sward composition and herbage biomass were determined for each plot using quadrat cuts. The sward composition and diet composition results obtained were used to calculate selectivity indices for individual dietary components. Green leaf of broad-leaved grasses was the main dietary component for both animal species on both the improved and unimproved grasslands. In general, the guanacos consumed less green grass leaf and more dead grass leaf than the sheep. Their diets also contained significantly more Nardus stricta than sheep diets. The sheep diets contained significantly more Trifolium repens, which was consistently avoided by the guanacos. Only one dicotyledonous species (Cirsium palustre) was consistently selected by the guanacos. There were fewer between-species differences in diet composition on the previously sheep-grazed plots than on the previously guanaco-grazed plots.

Bioenergy as a biodiversity management tool and the potential of a mixed species feedstock for bioenergy production in Wales

A cutting management regime maintains high levels of biodiversity in semi-natural habitats across Europe. We utilise three years of annual yield data from Welsh semi-natural areas to calculate the mean feedstock production from cutting management to be 1.05×10(6) t DM annum(-1). Using formulae based upon Fischer Tropsch (FT) fuel process models, we predict that 2.12×10(5) t of FT fuel annum(-1) could be produced. That represents 38% of the Welsh transport sectors green house gas (GHG) reduction target for 2020. Alternatively, predictive formulae reveal that methane yields from anaerobic digestion of the feedstock could reduce GHG emissions by 11% of the domestic sectors reduction target for 2020. Electricity generation from methane is also explored. The results presented encourage further investigation into the contribution of this resource to sustainable domestic energy supply. Furthermore, the proposed system would potentially protect a broad range of ecosystem services and maintain biodiversity.

Traditional vs modern: role of breed type in determining enteric methane emissions from cattle grazing as part of contrasting grassland-based systems

Ruminant livestock turn forages and poor-quality feeds into human edible products, but enteric methane (CH4) emissions from ruminants are a significant contributor to greenhouse gases (GHGs) and hence to climate change. Despite the predominance of pasture-based beef production systems in many parts of Europe there are little data available regarding enteric CH4 emissions from free-ranging grazing cattle. It is possible that differences in physiology or behaviour could influence comparative emissions intensities for traditional and modern breed types depending on the nutritional characteristics of the herbage grazed. This study investigated the role of breed type in influencing CH4 emissions from growing beef steers managed on contrasting grasslands typical of intensive (lowland) and extensive (upland) production systems. Using the SF6 dilution technique CH4 emissions were estimated for a modern, fast-growing crossbred (Limousin cross) and a smaller and hardier native breed (Welsh Black) when grazing lowland perennial ryegrass (high nutritional density, low sward heterogeneity) and semi-improved upland pasture (low/medium nutritional density, high sward heterogeneity). Live-weight gain was substantially lower for steers on the upland system compared to the lowland system (0.31 vs. 1.04 kg d−1; s.e.d. = 0.085 kg d−1; P<0.001), leading to significant differences in estimated dry matter intakes (8.0 vs. 11.1 kg DM d−1 for upland and lowland respectively; s.e.d. = 0.68 kg DM d−1; P<0.001). While emissions per unit feed intake were similar for the lowland and upland systems, CH4 emissions per unit of live-weight gain (LWG) were substantially higher when the steers grazed the poorer quality hill pasture (760 vs 214 g kg−1 LWG; s.e.d. = 133.5 g kg−1 LWG; P<0.001). Overall any effects of breed type were relatively small relative to the combined influence of pasture type and location.