Annex 2 Workshop report
1. Introduction
There is an increasing consumer desire and legislative requirement to move to a 100% organic feed for laying hens, but to do this successfully without harm to the hen and the environment, more organic sources of essential amino acids are needed.
On Thursday 6th of July 2006, a workshop was held at ADAS Gleadthorpe, presenting the results of a Defra-funded project: Organic egg production – a desk study on sustainable and innovative methods for meeting the hen's protein requirements (OF0357). This project, conducted by ADAS, examined the potential of novel protein sources such as algae, aquatic plants and macroinvertebrates (insects and earthworms) for feeding to organic laying hens.
The project identified a number of promising novel protein sources for use in UK organic egg production taking into consideration crude protein content, protein digestibility and amino acid supply. The effects of these novel protein sources on bird health and welfare, the environment, egg quality, quantity and nutrient content, and food safety were investigated in wide ranging literature sources. The project team also considered the requirements for producing, harvesting and processing the most promising novel protein sources in order to make an assessment of their suitability for use in organic farming systems. A cost-benefit analysis was done on the likely cost of feeding novel organic protein sources in relation to the price of organic soya.
The aim of the workshop was to present the scientific and technical results of the study. Approximately 30 people attended the workshop including representatives from Defra, the poultry industry (egg producers, packers, feed companies), supermarkets, organic certification bodies, research organisations and the press. This report gives the programme, brief summaries of the presentations of the speakers and summaries of the discussions that followed. The general discussion produced a list of points for further R&D.
Programme
10:30 / Arrival of delegates / Presenter / Summary section11:00-11:15 / Welcome
Background to project & Introduction / Dr Heleen van de Weerd
Mr Ray Keatinge (Chair)
11:15-12:15 / Alternative protein sources for organic hens – feeding value, health and welfare, egg quality, food safety & diet simulation studies / Ms Sue Gordon / 2.1
12:15-12:45 / Production methodologies of novel organic proteins: Insects & earthworms / Ms Monique Tomiczek / 2.2
12:45-13:45 / Lunch
13:45-14:25 / Production methodologies of novel organic proteins: Algae, herbs & aquatic plants / Dr Tamara Verhoeven / 2.3
14:25-14:55 / Impact of novel organic proteins on the environment / Dr Fiona Nicholson / 2.4
14:55-15:35 / Economic appraisal of the most promising novel organic protein sources / Mr Tony Turner / 2.5
15:35-16:15 / Discussion: future R&D & legislative implications / Mr Ray Keatinge
All speakers and the chairman are from ADAS
2. Speaker presentations
2.1 Alternative protein sources for organic hens – feeding value, health and welfare, egg quality,
food safety & diet simulation studies
Ms Sue Gordon
Sue Gordon is a senior research scientist working in the Poultry team of the Animal Health & Welfare business unit based at Gleadthorpe. Her areas of expertise are research and development related to poultry production, nutrition and welfare.
The project has identified a number of promising novel protein sources for feeding to organic laying hens and these include animal sources such as fly pupae and larvae meal and earthworm meal. Promising plant sources were microalgae such as Chlorella (a single-celled, non-motile green alga), Micractinium (a colonial algae) and Spirulina (Arthrospira, a filamentous, spiral-shaped, multicellular blue-green algae, cyanobacteria), protein-rich herbs such as purslane and to a lesser extent aquatic plants such as duckweed (e.g. Lemna gibba).
Questions that were used to review the literature were if any of these protein sources feature naturally in the diet of chickens (feral or domesticated), whether they are fed to captive birds, whether they are a food source for humans and what their potential would be in diets for organic laying hens. Feral chickens such as Red jungle fowl in N. India consume seeds, insects, spiders, snails, slugs, earthworms and lizards, berries and seeds. The crop contents of scavenging chickens in Ethiopia contained between 2.6% and 11.2% earthworms depending on season.
The feeding value of the novel protein sources was investigated (including ME value, protein content and quality, fat content and fatty acid profile, vitamin and mineral content, and heavy metal content). The effects of these novel protein sources on bird performance, health and welfare, egg quality, egg nutrient content and food safety were described.
Insects
There are published tables of the nutritional contents for a large number of edible insect species. Insect meals have been used in poultry diets e.g. house fly larvae and pupae, earthworms, silkworm pupae, grasshoppers, bees and crickets. The exoskeleton of insects is partly composed of chitin (polymer of N-acetyl-ß-D-glucosamine); it contains approximately 70 g/kg N (438 g/kg crude protein). However, no negative effects of high chitin content insect meals on poultry performance have been found. Furthermore, mRNA for gut chitinase has been reported for chickens from day seven of incubation, which suggests that chickens have some ability to digest chitin.
Fly pupae (www.insectary.com)
The crude protein content of earthworms ranges from 580-760 g/kg DM, but the crude protein content of fresh earthworms is only 110 g/kg. The content of individual amino acids differs between earthworm species by no more than 17% and usually by considerably less. The crude protein content of house fly pupae and larvae meal ranges from about 600-630 g/kg DM.
Bird health and welfare can be affected by eating insects through physical damage during transit through the gut (e.g. the spiny legs and wings of grasshoppers may puncture the crop of chickens and rupture the intestines) or because of the presence of toxins, antinutritionals or infectious disease causing agents.
Grasshopper (www.muextension.missouri.edu)
Feeding studies in chickens were reviewed. Earthworms can accumulate toxic residues, particularly heavy metals and agrochemicals, but no adverse effects on chicken health have been reported. Heavy metal contamination in earth worms depends on the source of metals, the species of earthworm and metal-metal interactions. The substrate and nutrient source used for earthworm meal production will be important. It is not known what the impact of earthworm meal intake on egg concentrations of heavy metals and contaminants is.
Microalgae, herbs and aquatic plants
The crude protein content of Chlorella has been reported to be 395.0 g/kg DM and for Spirulina between 600 and 760 g/kg DM. Sewage-grown Spirulina has between 535 and 590 g/kg DM crude protein. About 10% of the nitrogen (N) found in algae is non-protein N and the nucleic acid content is between 40 and 60 g/kg DM. Poultry are able to tolerate the high nucleic acid content as they excrete uric acid.
The ME value of duckweed is low (5.0 MJ/kg) because of its high ash content (184 g/kg DM). The crude protein content of duckweed obtained from natural waters ranges from 70 to 200 g/kg DM, whereas the crude protein content of duckweed grown in lagoons enriched with sewage or manures ranges from 300 to 400 g/kg DM. It has slightly poorer lysine and methionine plus cystine contents than soya bean meal.
Sewage grown algae can accumulate toxic residues, particularly heavy metals, but no ill effects on chicken health were found in feeding studies. In a study heavy metal-rich algae meals were fed, but despite this, heavy metal concentrations in the meat were normal.
An issue with feeding microalgae to laying hens may be egg yolk colour, which might be unacceptably bright due to algae having very high xanthophyll contents. Chlorella meal contains between 650 and 1100 mg/kg xanthophylls. Modest dietary concentrations of Spirulina (only 30 g/kg) produced yolks having a high Roche score (13.3). Chlorella meal may be fed at concentrations up to 100 g/kg, before yolk colour is adversely affected, and possibly at higher concentrations, the maximum dietary concentration of Spirulina should be 10 g/kg.
There are benefits to bird health when feeding Spirulina, an important one is a lower mortality in quail, turkey poults, broilers and laying hens. Furthermore, immunomodulatory effects in chickens fed only 10 g/kg Spirulina have been reported and also immunostimulatory activity (due to a high molecular weight polysaccharide).
Reported benefits to human health are that enzymatic hydrolates in Spirulina promote enhanced skin metabolism and there is anti-tumour activity. Chlorella has been shown to have antibiotic activity against gram positive and gram negative bacteria and it has anti-viral activity, it is also used in the treatment of allergic and anaphylactic reactions.
Purslane leaves have a crude protein content of up to 443 g/kg DM. The lysine content is between 6.3 and 6.9 g/100g protein and methionine plus cystine contents are between 1.3 and 1.4 g/100 g protein. Purslane is a rich source of linolenic acid and in Greece free-ranging chickens foraging purslane produce n-3 fatty acid rich eggs.
Purslane (www.weeds.cropsci.uiuc.edu)
Diet formulation and N excretion
Diets were formulated using the most promising novel (organic) ingredients. The information used was derived from the literature on suggested maximum dietary concentrations and nutrient contents. The target nutrient specifications set prior to the formulation were based on published recommendations (NRC, 1994 and breeder company information). The diets were compared with diets formulated using typical available organic protein sources in terms of nutrient supply and calculated rates of nitrogen (N) excretion. The organic rations including the novel protein sources were formulated by Dr Bruce Cottrill from ADAS. Thirteen different diets were formulated, including diets containing house fly pupae meal, earthworm meal, Chlorella meal or a combination of the ingredients. The results of diet simulation studies showed that the ME values were mostly below target and the dietary crude protein content was too high in some cases. There tended to be an over-supply lysine and tryptophan was mostly over-supplied. In some cases the total P content was above the target concentration and the electrolyte balance was often not optimal, with excesses and/or deficiencies.
The rates of N excretion for the different novel protein diets were calculated using balance calculations which take into account N intake, N retention and egg N output over a laying cycle or year (allows for % occupancy).
Conclusions
§ Novel protein sources are a huge biomass and they are under utilised
§ There is great potential to develop some as feedstuffs for organic laying hens and they offer potential with regards to recycling nutrients, which is in-keeping with the organic ethos
§ Protein contents are moderate to high, but more information is needed on protein digestibility and amino acid availabilities
§ There are health benefits associated with some novel protein sources (immuno-competence, antibacterial and antiviral activity), it is not known whether they have any antiparasitic activity
§ Some novel protein sources are a rich source of xanthophyll pigments, which may be helpful for organic egg yolk colouration (whole eggs, egg products, confectionery)
§ Evidence suggests that the novel proteins studied would not pose a risk to food safety (heavy metal content and microbial contamination), but studies are needed on organically produced sources
§ Organic egg nutrient contents are unlikely to be greatly affected by novel protein sources
§ The most favourable simulated diets (housefly pupae meal2, Chlorella meal + housefly pupae meal and Chlorella meal + earthworm meal) gave lower calculated rates of N excretion
Knowledge gaps
§ We need knowledge on the effects of organic production methodologies including the effects of drying on protein content and quality, on lipid and ash contents, and on ME value
§ Feeding studies in organic laying hens are needed to find out about the performance, egg quality and gross margins
§ There is a need to assess the health and welfare benefits of novel organic protein sources on immunocompetence and mortality in an organic egg production system, including information on litter quality, bone strength and the incidence of feather pecking
§ To determine the risks to food safety when feeding organic hens organically produced novel proteins
§ There is a need to determine the xanthophyll content of organically produced novel protein sources, their pigmenting potencies and the acceptability of yolk colour to UK organic egg consumers
§ There is a need to determine whether there are effects of organically produced novel protein sources on organic egg flavour
2.2 Production methodologies of novel organic proteins: Insects & earthworms
Ms Monique Tomiczek
Monique Tomiczek works as a research entomologist in the Sustainable Crop Management business unit based at ADAS Boxworth. Her areas of expertise are biological control and integrated pest management.
Earthworm (Vermiculture) production
Earthworm production systems require the efficient conversion of organic wastes into earthworm tissue protein to generate a rapid rate of growth and multiplication of earthworms. Such systems range from simple low-cost structures, such as windrows or boxes, to complex mechanised systems, which are expensive to set up but are more efficient and much less labour intensive.
The basic principle of all breeding systems is to add wastes frequently in thin layers (as earthworms tend to be concentrated in the top 15 cm of waste) and allow the earthworms to process successive layers of waste and subsequently mature and multiply. Maximum productivity can be achieved by maintaining the waste at optimal moisture and temperature (depends on the species of earthworm used, Table 1), maintaining aerobic conditions and avoiding excessive amounts of ammonia and salts in the waste.
Table 1. Productivity of earthworms in animal & vegetable wastes
Eisenia fetida / 10.4 / 0.55 / 8.4
D. veneta / 1.4 / 0.92 / 8.1
Eudrilus eugeniae / 6.7 / 4.3 / 5.0
Perionyx excavatus / 19.4 / 1.3 / 4.0
Wastes containing high levels of ammonia, such as fresh poultry litter, can still be used as long as excessive ammonia and salts are removed first by a period of composting or washing. To achieve all year-round production, UK production systems may need to be done under cover, although heating may not be necessary as decomposing waste gives off some heat.