Smith, J.

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  Tree fodder: food for thoughts?  3244th European Agroforestry Conference  Agroforestry as Sustainable Land Use TREE FODDER IN UK LIVESTOCK SYSTEMS: OPPORTUNITIES AND BARRIERS Smith J1*, Westaway S1, Whistance L1 (1) Organic Research Centre, Newbury, UK  *Corresponding author: jo.s@organicresearchcentre.com  Abstract In northern European countries, there is little current understanding of the potential of tree fodder. This paper discusses the opportunities and barriers for tree fodder into UK ruminant livestock systems. Key opportunities include improving livestock nutrition and health (particularly as sources of minerals), and as a buffer against climate change impacts or shortages of forage. Key barriers are the mechanisation and management of tree fodder to reduce labour input, and regulatory restrictions that prevent tree and hedge cutting in summer months. Much of the information on tree fodder is anecdotal, and there is a real need for both scientific evidence and practical management advice on differences between tree species and seasonal variations in nutritional value. To take full advantage of this potential, better understanding of the nutritional and health benefits of tree fodder, and more efficient management techniques need to be developed.  Keywords: minerals; tannins; salicylic acid; silvopastoral systems  Introduction Traditionally, tree fodder has been an important animal feed and remains significant in some farming systems (Eichhorn et al. 2006). However, in northern European countries, while the value of trees for shelter or shade is accepted, there is little current understanding of the potential of tree fodder. Nevertheless, tree fodder offers certain benefits such as buffering against the impact of climate change on forage resources, and meeting specific nutritional or health needs of the animals. The need for better estimates of the nutritional value of browse in relation to management of trees (e.g. impact of harvesting style on the quantity or quality of forage) was identified by European livestock stakeholders as a barrier to greater uptake of agroforestry systems (Hermansen et al. 2015). Can this traditional labour-intensive practice work in modern livestock systems? This paper discusses the potential integration of tree fodder into UK ruminant livestock systems. In addition to a brief overview of available evidence, results from tree fodder analyses carried out as part of the European research project AGFORWARD are presented and discussed.  What are the benefits of, and barriers to, wider use of tree fodder in the UK? a) Livestock nutrition and health. Fodder from some tree species compare favourably with typical forages such as hay, grass silage and grazed grass (Ministry of Agriculture Fisheries and Food 1990). Of greater value, however, may be their potential as a source of minerals. For example, willow leaves are high in magnesium and zinc (Robinson et al. 2005) and alder is high in copper (Luske and Van Eekeren 2017). Secondary compounds such as condensed tannins can also be of benefit by increasing the flow of rumen-bypass protein and essential amino acids to the small intestine (Rogosic et al. 2006). The potential for self-medication in ruminants is not yet well explained in the scientific literature. Although salicin, in willow, is well known to have anti-inflammatory properties, it has not been widely evaluated in terms of its content within tree fodder or consequent effects on animal health (Boeckler et al. 2011). Comparatively little is known about the potential of temperate browse species, although the evidence base is slowly   Tree fodder: food for thoughts?  3254th European Agroforestry Conference  Agroforestry as Sustainable Land Use growing (Emile et al. 2016; Smith et al. 2012) and contributing to an on-line database of nutritional values (Luske et al. 2017). b) Buffer against climate change impacts or shortages of forage. Trees provide alternative feed resources during periods of low forage availability. In northern temperate systems, this role mayincrease in importance as the effects of climate change impact on plant growth patterns. There (Green 2016), or ensiled (Smith et al. 2014)). c) Mechanisation and management. The simplest method of managing tree fodder is to allow livestock to have direct access, although this requires careful management that balances keeping tree height accessible to livestock with minimising damage to the tree. Manual cutting and transporting is laborious and time consuming, but there has been recent interest in mechanising the process; Dutch farmers have been investigating ensiling coppiced willow for feeding to dairy goats (see www.voederbomen.nl/oogst for a film of the process).  d) Regulatory restrictions. In England, under Cross Compliance regulations (which farmers must follow if they are claiming rural payments such as for the Basic Payment Scheme or Countryside Stewardship), hedges and trees must not be cut between 1st March and 31stAugust (although it is possible to coppice trees between 1st March and 30th April) (DEFRA 2017). This conflicts with tree fodder management options which would need to be done during the summer months. Direct browsing would still be possible though. e) Knowledge gaps. Much of the information on tree fodder is anecdotal, and there is a real need for both scientific evidence and practical management advice on differences between tree species, seasonal variations in nutritional value and appropriate management systems.   Tree fodder analyses Leaf samples were collected from SRC alder (Alnus glutinosa) and basket willow (Salix viminalis) in August 2015, and in June 2016 from an ash (Fraxinus excelsior), goat willow (Salix caprea) and elm (Ulmus minor) tree on Elm Farm, Hamstead Marshall, UK (. As part of a pilot study on the effect of air-drying tree fodder over winter and testing palatability, branches of the ash, goat willow and elm were bundled, tied and left to dry naturally in a covered barn from June to March (Figure 1a). Leaf samples were then taken before the bundles were fed to housed cattle (Figure 1b and see video at https://vimeo.com/217077820). Leaf samples were oven dried at 40°C until a stable weight was reached, and analysed for neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and digestible organic matter (DOM) by INRA in France, and for Ca, P, N, Mg, S, K, Fe, Mn, Cu, Zn and B by NRM (www.nrm.uk.com). Results contributed to the Tree Fodder on-line database managed by the Louis Bolk Institute (http://www.voederbomen.nl/nutritionalvalues/).       Figure 1: (a) Harvesting and bundling tree fodder from an ash tree, June 2016 (b) feeding air-dried tree fodder to cattle, March 2017.   Tree fodder: food for thoughts?  3264th European Agroforestry Conference  Agroforestry as Sustainable Land Use Digestible organic matter (DOM) varied between species, with lowest levels recorded for Salix viminalis samples collected in August (Table 1). Similarly low levels (42.1%) were recorded in Salix viminalis samples from a UK silvoarable SRC system (Smith et al. 2012). However, DOM of the other species was higher (Table 1) and compares favorably with typical livestock forages. Lignin levels were higher in the Salix viminalis and Alnus glutinosa samples compared to the other three species; this may, however, be due to the samples being taken in August when leaves have matured and become lignified rather than reflecting any species differences.  Table 1: Chemical composition of tree leaves including neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and digestible organic matter (DOM). DM=dry matter. Latin name Date sampled DM (%) NDF (%DM) ADF (%DM) Lignin (%DM) DOM  (%) Salix viminalis Aug-15 33 37.29 22.12 11.33 55.29 Alnus glutinosa Aug-15 38 37.61 24.76 13.51 76.19 Fraxinus excelsior Jun-16 39 29.59 14.84 5.02 85.68 Salix caprea Jun-16 35 32.15 20.57 8.77 73.51 Ulmus minor Jun-16 37 43.06 12.15 3.31 77.72  The content of selected essential macro- and micro- minerals was tested for the five species of trees. Essential minerals are those which are known to have a metabolic function in animals or plants. All the tested elements increased in the air-dried leaves compared to fresh leaves although where levels were low in the fresh samples, this increase was minimal (Table 2). Levels of phosphorus (an essential element for bones) were highest in the dried goat willow (5.5 g/kg DM) but all trees compare favourably with grass at 2.8-3.5 g/kg DM, silage at 2.0-4.0 g/kg DM and hay at 1.5-3.5 g/kg DM (McDonald et al. 1995).  Table 2: Macro-elements of tree leaves. Latin name Date sampled Ca (g/kg DM) P (g/kg DM) N (% w/w) Mg (g/kg DM) S (g/kg DM) K (g/kg DM) Salix viminalis Aug-15 18.8 3 2.23 1.8 4.1 10.4Alnus glutinosa Aug-15 13.3 2.2 3.16 2.5 1.9 9.1 Fraxinus excelsior Jun-16 12.8 3.1 1.78 2.2 1.8 14.1F. excelsior (dried) Jun-16 16 3.7 2.21 2.7 2.3 20 Salix caprea Jun-16 10.2 4.2 2.66 1.9 2.1 13.9S. caprea (dried) Jun-16 14.5 5.5 2.16 2.7 2.6 19.0Ulmus minor Jun-16 11 2.3 2.23 1.9 1.3 14.7U. minor (dried) Jun-16 16.8 2.4 2.31 2.8 1.7 20.9 With regards micro-elements, willow was particularly high in zinc, with Salix caprea containing 144 mg/kg DM and Salix viminalis containing 245 mg/kg DM (Table 3) reflecting previous findings (e.g. Robinson et al. 2005). The level of zinc in willow is substantially higher than those found in grass at 5 mg/kg DM, in silage at 25-30 mg/kg DM and in hay at 17-21 mg/kg DM (McDonald et al. 1995). Zinc is present in all animal tissue, organs and bones, playing an important role in growth, cell repair, hormones, enzyme activation, the immune system, and skin integrity. Levels of iron were notably high in the dried samples and in elm, in particular, at 258 mg/kg DM (Table 3). Salix viminalis and Alnus glutinosa contained substantially higher levels of manganese than did other tree species (Table 3).     Tree fodder: food for thoughts?  3274th European Agroforestry Conference  Agroforestry as Sustainable Land Use Table 3: Micro-elements of tree leaves. Latin name Date sampled Fe (mg/kg DM) Mn (mg/kg DM) Cu (mg/kg DM) Zn (mg/kg DM) B (mg/kg DM)Salix viminalis Aug-15 73 284 5.5 245 36.7Alnus glutinosa Aug-15 92 129 11.2 53 28.9Fraxinus excelsior Jun-16 91 25 7.4 18 15.7F. excelsior (dried) Jun-16 116 32 9.6 23 17.5Salix caprea Jun-16 76 36 7.6 118 12.7S. caprea (dried) Jun-16 142 46 10.9 144 18.2Ulmus minor Jun-16 138 37 6.5 32 19.3U. minor (dried) Jun-16 258 38 9.3 40 26.0 Conclusion Tree fodder has the potential to play a role in modern livestock systems in the UK; in particular the high levels of minerals in tree fodder suggest that trees can offer an alternative source of supplementation. The higher levels in dried samples, compared to fresh, suggest that there is scope to extend their value beyond the growing season. To take full advantage of this potential,better understanding of the nutritional and health benefits of tree fodder, and more efficient management techniques need to be developed.  Acknowledgements Thanks to Philippe Barre and the team at INRA for analysing the tree fodder, and to Ted Green and Alun Davies for help with collecting the samples. The AGFORWARD project (Grant Agreement N° 613520; 2014-2017) was co-funded by the European Commission, Directorate General for Research & Innovation, within the 7th Framework Programme of RTD, Theme 2 -Biotechnologies, Agriculture & Food.    References  Boeckler GA, Gershenzon J, Unsicker SB (2011) Phenolic glycosides of the Salicaceae and their role as anti-herbivore defenses. Phytochemistry 72: 1497-1509. DEFRA (2017) The guide to cross compliance in England 2017.  Eichhorn MP, Paris P, Herzog F, Incoll LD, Liagre F, Mantzanas K, Mayus M, Moreno G, Papanastasis VP, Pilbeam DJ, Pisanelli A, Dupraz C (2006) Silvoarable systems in Europe - past, present and future prospects. Agrofor Syst67: 29-50. Emile JC, Delagarde R, Barre P, Novak S (2016) Nutritive value and degradability of leaves from temperate woody resources for feeding ruminants in summer.  3rd European Agroforestry Conference, Montpellier, pp 409-412. Green E (2016) Forgotten food - tree hay. 3rd European Agroforestry Conference, Montpellier.  Hermansen JE, Kongsted AG, Bestman M, Bondesan V, Gonzalez P, Luske B, McAdam J, Mosquera-Losada MR, Novak S, Pottier E, Smith J, van Eekeren N, Vonk M, Burgess PJ (2015) Agroforestry Innovations to be evaluated for Livestock Farmers. Milestone 5.2 (MS 21) for EU FP7 Research Project: AGFORWARD 613520.Luske B, Meir Iv, Altinalmazis Kondylis A, Roelen S, Van Eekeren N (2017) Online fodder tree database for Europe. Loius Bolk Institute and Stichting Duiboeren, The Netherlands. Luske B, Van Eekeren N (2017) Nutritional potential of fodder trees on clay and sandy soils. Agroforestry Systems McDonald P, Edwards RA, Greenhalgh JFD, Morgan CA (1995) Animal Nutrition. Addison Wesley Longman Limited, Harlow, UK. Ministry of Agriculture Fisheries and Food (1990) UK tables of nutritive value and chemical composition of feedstuffs. Rowett Research Institute, Aberdeen, Scotland. Robinson BH, Mills TM, Green SR, Chancerel B, Clothier BE, Fung L, Hurst S, McIvor I (2005) Trace element accumulation by poplars and willows used for stock fodder. New Zealand J Agr Res 48: 489-497 Rogosic J, Pfister JA, Provenza FD, Grbesa D (2006) Sheep and goat preference for and nutritional value of Mediterranean maquis shrubs. Small Ruminant Res 64: 169-179. Smith J, Leach K, Rinne M, Kuoppala K, Padel S (2012) Integrating willow-based bioenergy and organic dairy production - the role of tree fodder for feed supplementation. Tackling the future challenges of organic husbandry Proceedings of the 2nd OAHC, Hamburg, Germany. Smith J, Kuoppala K, Yañez-Ruiz D, Leach K, Rinne M (2014) Nutritional and fermentation quality of ensiled willow from an integrated feed and bioenergy agroforestry system in UK. Maataloustieteen Päivät 30  

Tree fodder in UK livestock systems: opportunities and barriers

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Tree fodder in UK livestock systems: opportunities and barriers

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