Organic Egg Production Research Articles

Helminth infection is associated with hen mortality in Danish organic egg production

The aim of this study was to investigate whether two highly prevalent helminth infections (Ascaridia galli and Heterakis species) are associated with an increased mortality rate for hens at the...

The development of organic egg production in Turkey

The development of organic egg production in Turkey

Organic egg production. I: Effects of different dietary protein contents and forage material on organic egg production, nitrogen and mineral retention and total tract digestibility of nutrients of two hen genotypes

The purpose of the study was to determine the effect of organic layer diets differing in protein and amino acid content on egg production and feed intake with two hen genotypes. Three experimental layer diets A, B and C were formulated to contain decreasing content of protein (A: 193g/kg, B: 187g/kg, C: 170g/kg) but with similar energy content (average: 11.3MJ ME/kg). No synthetic amino acids were added to the diets in line with the organic legislation, so the content of amino acids changed with the different protein content (e.g. methionine, A: 3.6g/kg, B: 2.8g/kg, C: 2.6g/kg). Diets A, B and C were fed to both genotypes (Lohmann Silver (LS); New Hampshire (NH)), together with maize silage and carrots or alfalfa silage in a complete randomised design with 4 replicate pens each of 25 hens (total 1200 hens). Each pen had a separate house and outdoor hen yard of 4m2/hen. The experiment was carried out from 18 to 41 weeks of age, and layer diets and foraging material were fed ad libitum. A balance and digestibility experiment was performed at the end of the production study. The production parameters were significantly affected by genotype, diet and foraging material. The NH genotype had an average laying rate of 70%, compared to 85% for LS, (P<0.001). The FCR was also most efficient with LS hens fed diet A, and there was a significant effect of genotype (P=0.001; LS<NH) and diet (P=0.008; A<B=C) on FCR. Both genotypes showed preference for maize silage and carrots (104g/hen/d) compared to alfalfa silage (57g/hen/d), which reduced diet intake for both NH and LS given maize silage and carrots (P=0.002). This decreased laying rate with diet B and C, which could indicate insufficient supply of essential amino acids. The retentions of N and P were low, however, the N content in excreta was significantly influenced by both genotype (P=0.002; NH>LS), diet (P=0.004; A>B=C) and forage material (P<0.001; Alfalfa silage>maize silage plus carrots). Ca retention was significantly higher with LS hens (P<0.001), and with diet A compared to diet B and C (P=0.015). The coefficient of total tract digestibility (CTTAD) of the different nutrients was affected differently, having only minor effect on CTTAD of starch, being high in all groups. The CTTAD of methionine and cysteine was higher with diet A, compared with B and C (P<0.001). It is concluded that protein and amino acid content and high intake of foraging material influence production parameters in both genotypes, where LS performed more efficiently than NH. The hens obtain most likely some nutrients from the high intake of maize silage plus carrots and alfalfa silage, however, the foraging material have diluted the total intake of nutrients to some extent, which possibly influenced the results obtained on the overall production parameters.

Assessing the sustainability of egg production systems in The Netherlands

Housing systems for laying hens have changed over the years due to increased public concern regarding animal welfare. In terms of sustainability, animal welfare is just one aspect that needs to be considered. Social aspects as well as environmental and economic factors need to be included as well. In this study, we assessed the sustainability of enriched cage, barn, free-range, and organic egg production systems following a predefined protocol. Indicators were selected within the social, environmental, and economic dimensions, after which parameter values and sustainability limits were set for the core indicators in order to quantify sustainability. Uncertainty in the parameter values as well as assigned weights and compensabilities of the indicators influenced the outcome of the sustainability assessment. Using equal weights for the indicators showed that, for the Dutch situation, enriched cage egg production was most sustainable, having the highest score on the environmental dimension, whereas free-range egg production gave the highest score in the social dimension (covering food safety, animal welfare, and human welfare). In the economic dimension both enriched cage egg and organic egg production had the highest sustainability score. When weights were attributed according to stakeholder outputs, individual differences were seen, but the overall scores were comparable to the sustainability scores based on equal weights. The provided method enabled a quantification of sustainability using input from stakeholders to include societal preferences in the overall assessment. Allowing for different weights and compensabilities helps policymakers in communicating with stakeholders involved and provides a weighted decision regarding future housing systems for laying hens.

Organic egg production. II: The quality of organic eggs is influenced by hen genotype, diet and forage material analyzed by physical parameters, functional properties and sensory evaluation

The purpose of the study was to determine, how the dietary nutrients available in organic egg production, and especially how the obligatory forage material in relation to two different hen genotypes affects the quality of organic eggs evaluated by physical, functional and sensory properties. The experimental treatments were subjected to a total of 1200 hens, which were of two hen genotypes, representing a high egg yielding hybrid; Lohmann Silver (LS), and a dual-purpose hen genotype; New Hampshire (NH). They were fed three experimental feed diets (A, B and C), which were intended to differ in protein contents, hence methionine contents. Protein content of diets A, B and C were on average 203, 199, and 182g/kg dry matter, respectively, and methionine content were on average 3.9, 3.1, and 3.0g/kg dry matter, respectively. Furthermore, two forage material treatments were supplied (maize silage+carrots and alfalfa silage), altogether distributed in a complete randomized design with 4 replicate pens each of 25 hens. Each replicate pen had a separate house and outdoor hen yard of 4m2/hen. Eight times during the experimental period, from 22 to 41 weeks of age, eggs were collected for analysis of egg weight, egg dimensions, shell strength, egg yolk colour, carotenoid content of yolk, albumen pH, albumen DM, and albumen gel textural properties. Twice during the study, boiled eggs were evaluated for sensory properties. The results showed the hen genotype significantly influenced all analyzed egg quality parameters. Furthermore, the nutrient content of the diets significantly affected the egg weight and dimension, the shell fracture force, egg yolk colour, and carotenoid content. The forage material type also affected the egg quality. Feeding the alfalfa silage resulted in eggs of higher weight, no effect on shell quality, egg yolk colours of higher darkness, redness and yellowness, and a higher content of pigmenting carotenoids, but lower content of carotenes (α- and β-). No overall sensory differences of eggs from hens fed the two forage materials appeared, although some interaction effects were seen and are discussed.In conclusion, the egg quality in organic egg production is highly affected by the hen genotype, while further influence of the diet and forage material on the egg quality depends on the specific nutrients and compositions hereof.

Welfare of organic laying hens kept at different indoor stocking densities in a multi-tier aviary system. II: live weight, health measures and perching

Multi-tier aviary systems, where conveyor belts below the tiers remove the manure at regular intervals, are becoming more common in organic egg production. The area on the tiers can be included in the net area available to the hens (also referred to as usable area) when calculating maximum indoor stocking densities in organic systems within the EU. In this article, results on live weight, health measures and perching are reported for organic laying hens housed in a multi-tier system with permanent access to a veranda and kept at stocking densities (D) of 6, 9 and 12 hens/m2 available floor area, with concomitant increases in the number of hens per trough, drinker, perch and nest space. In a fourth treatment, access to the top tier was blocked reducing vertical, trough, and perch access at the lowest stocking density (D6x). In all other aspects than stocking density, the experiment followed the EU regulations on the keeping of organic laying hens. Hen live weight, mortality and foot health were not affected by the stocking densities used in the present study. Other variables (plumage condition, presence of breast redness and blisters, pecked tail feathers, and perch use) were indirectly affected by the increase in stocking density through the simultaneous reduction in access to other resources, mainly perches and troughs. The welfare of the hens was mostly affected by these associated constraints, despite all of them being within the allowed minimum requirements for organic production in the EU. Although the welfare consequences reported here were assessed to be moderate to minor, it is important to take into account concurrent constraints on access to other resources when higher stocking densities are used in organic production.

Welfare of organic laying hens kept at different indoor stocking densities in a multi-tier aviary system. I: egg laying, and use of veranda and outdoor area

Multi-tier aviary systems are becoming more common in organic egg production. The area on the tiers can be included in the net area available to the hens (also referred to as usable area) when calculating maximum indoor stocking densities in organic systems within the EU. In this article, results on egg production, laying behaviour and use of veranda and outdoor area are reported for organic laying hens housed in a multi-tier system with permanent access to a veranda and kept at stocking densities (D) of 6, 9 and 12 hens/m2 available floor area, with concomitant increases in the number of hens per trough, drinker, perch and nest space. In a fourth treatment, access to the top tier was blocked reducing vertical, trough and perch access at the lowest stocking density (treatment D6x). In all other aspects than stocking density, the experiment followed the EU regulations on the keeping of organic laying hens. Laying percentage was significantly lower (P<0.05) in D12 compared with the other stocking densities (90.6% v. 94.3% (±0.7)), most likely due to the concomitant reduction in nest space and drinker availability per hen. No systematic effects of density were found on other laying variables (egg weight, eggs laid outside nests, aviary side preferences). Number of hens using the veranda increased with stocking density. Hens primarily used the range near the house (within 50 m) and hens kept at the lowest stocking density and the smallest group size appeared to use the outdoor area more extensively, based on an assessment of vegetation cover (P<0.05). For the measures reported here, the welfare consequences of increased stocking density were assessed to be minor; additional results are reported in the associated article (Steenfeldt and Nielsen, 2015).

Effect of origin and composition of diet on ecological impact of the organic egg production chain

The objective of this research was to assess the potential to reduce the integral ecological impact (i.e. impact along the egg production chain per kg egg) of Dutch organic egg production by replacing currently used imported diet ingredients with Dutch diet ingredients. We realized this objective by comparing the life cycle assessments (LCA) of current Dutch organic egg production, i.e. base situation (B) with different scenarios. In each scenario, one imported diet ingredient was replaced with a diet ingredient produced in the Netherlands. Finally, we formulated a scenario in which several ingredients, that individually resulted in the lowest mean change in ecological impact along the organic egg production chain, were replaced simultaneously. We included differences between production chains in cultivation (i.e. field operation, manure application and yield), transport, feed intake, egg production and N excretion.Replacement of Ukrainian wheat with Dutch triticale, and of Brazilian soybeans, Italian sunflower seed expeller and German peas with Dutch rapeseed expeller reduced the integral ecological impact compared with current organic egg production. Simultaneous replacement of these ingredients (scenario MU) resulted in an overall lower and more balanced reduction of the different ecological impacts (41–101%) than single replacement of these ingredients (41–215%). Compared with B ecological impact of scenario MU decreased for global warming potential (91%), energy use (79%), land occupation (68%), acidification potential (99%), N deficit (85%), P deficit (41%) and P surplus (81%), but slightly increased for N surplus (101%). The low ecological impact of MU was explained by (1) a relative small increase in feed conversion ratio (from 2.32 for B to 2.37 for MU), (2) a reduction of the transport distance of 44.4% of the diet ingredients, (3) replacement of the currently used crops with crops that have a higher yield in combination with a balanced applied amount of N and P in manure, and (4) use of expeller instead of whole ingredients.

Total loss and distribution of nitrogen and phosphorus in the outdoor run of organic laying hens

1. The objective of this study was to determine the level and variation of the total mass, and load of nitrogen (N) and phosphorus (P) excreted into the outdoor run of organic egg production systems. 2. Three egg production farms with an aviary system and an outdoor run were selected for this study. Four measurements, one per season, were executed on each farm. 3. Mean content of N and P of a manure dropping was 14·0 g N kg−1 and 3·12 g P kg−1, mean mass of a dropping was 6·36 g and mean dry matter content of a dropping was 238 g kg−1. Mean rate of excretion in the outdoor run was 2·99 droppings per hen per h. Mean percentage of hens outside during the time the outdoor run could be accessed was lowest on Farm 1 (1·7%), highest on Farm 2 (16·0%), and intermediate on Farm 3 (7·1%). 4. On all farms an exponential decrease of the number of hens and of the load of N and P with increasing distance from the hen house was found. Load of N exceeded the fertilisation standard (of 170 kg ha−1 y−1) in the region at a 0 to 19 m distance from the hen house on Farm 1, 0 to 146 m on Farm 2 and 0 to 52 m on Farm 3. 5. It is concluded that the husbandry system should be redesigned to solve the problem of overloading, unwanted loss of N and P to the environment and loss of N and P from the organic production cycle.

The effects of kale (Brassica oleracea ssp. acephala), basil (Ocimum basilicum) and thyme (Thymus vulgaris) as forage material in organic egg production on egg quality

1. In organic egg production, forage material as part of the diet for laying hens is mandatory. The purpose of the present study was to examine the effect of feeding with forage materials including maize silage, herbs or kale on egg production and various egg quality parameters of the shell, yolk colour, egg albumen, sensory properties, fatty acid and carotenoid composition of the egg yolk. 2. A total of 5 dietary treatments were tested for 5 weeks, consisting of a basal organic feed plus 120 g/hen.d of the following forage materials: 1) maize silage (control), 2) maize silage incl. 15 g/kg basil, 3) maize silage incl. 30 g/kg basil, 4) maize silage incl. 15 g/kg thyme, or 5) fresh kale leaves. Each was supplied to three replicates of 20 hens. A total of 300 hens was used. 3. Feed intake, forage intake and laying rate did not differ with treatment, but egg weight and egg mass produced increased significantly with the kale treatment. 4. The egg shell strength tended to be higher with the kale treatment, and egg yolk colour was significantly more red with the kale treatment and more yellow with basil and kale treatments. The albumen DM content and albumen gel strength were lowest with the thyme treatment. By sensory evaluation, the kale treatment resulted in eggs with less sulphur aroma, higher yolk colour score, and more sweet and less watery albumen taste. Furthermore, the eggs of the kale treatment had significantly higher lutein and β-carotene content. Also, violaxanthin, an orange xanthophyll, tended to be higher in kale and eggs from hens receiving kale. 5. In conclusion, forage material, especially basil and kale, resulted in increased egg production and eggs of high and differentiable quality.

Overview of natural and organic egg production: Looking back to the future

The US egg industry has grown dramatically in the past, with a significant component of that growth focusing on alternative production systems such as cage-free or range egg production. Constituents of this growth involving intensive egg production create uncertainty in relation to the future because of concerns about the impact of the cage environment on laying hen well-being. Both the commercial egg production sector and small producers using heritage strains of chickens, in flocks ranging in size from 100 to 3,000 hens, are responding by producing eggs in both cage-free and range settings. However, one of the current issues is that our knowledge base of how these alternative production methods influence egg performance and quality characteristics is limited to research studies that were conducted in the late 1940s and early 1950s. This information was collected with specific breeds, and not with modern lines of poultry that have been selected for very high rates of egg production. Therefore, an examination of alterative laying hen husbandry practices in the context of the current knowledge base would provide beneficial information to identify how these husbandry and feeding practices translate to modern strains of laying hens under cage-free or range production. Research on range or cage-free production done in controlled settings is limited, and additional studies relevant to egg producers wishing to expand cage-free and range egg production are needed.

Feeding layers of different genotypes in organic feed environments

1. Two experiments were carried out to evaluate the suitability of an experimental laying hen genotype (SH) in organic egg production. SH had been selected over 25 generations on a low protein diet (130 g/kg) based on home grown feedstuffs. SH hens were compared with LSL (Experiment 1) and Hyline (Experiment 2) hens. The birds were kept in 12 aviary pens with access to outdoor runs. 2. Four diets, which were different in each experiment, were used. A control diet was compared with diets based on feedstuffs supposed to be able to be grown and produced according to organic standards. The diets differed in the content of sulphur amino acids. 3. There were no significant differences in mortality caused by diets or genotypes but an incidence of cannibalism occurred in one Hyline group fed on the diet with the lowest methionine content. 4. Severe feather pecking of LSL birds occurred and was worst on the low protein diet. In Experiment 2, signs of feather pecking of birds on the low protein diet occurred at the end of the experiment, but there was no difference between the genotypes. There was no significant difference in number of eggs produced between diets. Egg weight was influenced by diets in both experiments and by genotype in Experiment 2. Number of misplaced eggs was higher in SH hens in both experiments. There were few significant diet × genotype interactions. 5. The use of the outdoor area was influenced by diets and genotype in both experiments. 6. In conclusion, diets low in methionine content influenced predominantly plumage condition and egg weight, although production of eggs by number was unaffected. The SH hen adapted well to organic conditions, as did the Hyline genotype.

A note on light preference in layer pullets reared in incandescent or natural light

The effect of early exposure of pullets to natural light may have an effect on the later preference for light type and on the behaviour of birds after being transferred to laying facilities. Our aim was to study the light-type preference of 14-week pullets reared in either incandescent or natural light. From day-old, a total of 84 LSL chicks were subjected to two light treatments with six groups of seven birds each: 8 h incandescent light + 16 h darkness (I8), and 8 h natural light + 16 h darkness (N8). At the age of 14 weeks, the birds’ light-type preference was tested. Behaviour was recorded at the group level and analysed by a linear mixed model. Predicted mean proportion of birds that chose natural light was 0.36 in N8 and 0.13 in I8 groups. I8 groups showed a preference for incandescent light, in contrast to N8. These results support the notion that pullets for organic egg production shall be reared with access to natural light.

On-farm welfare assessment systems: what are the recording costs?

AbstractTo illustrate that different approaches lead to different costs a cost calculation on four different welfare assessment systems for four different animal species has been carried out; an integrated pig herd (450 sows), a dairy cattle herd with automatic milking (90 cows), an organic egg production system (3000 layers) and a mink farm (1000 mink). We calculated the cost to be: €375 per annum for the mink farm and €2205, €2430 and €2435 for the egg production system, the AMS dairy herd and the integrated pig farm, respectively. The costs can be reduced by: reducing the number of indicators and/or the recording frequency, reducing sample sizes, more intensive use of existing data and by exchanging external for internal recordings.

Measuring fearfulness of hens in commercial organic egg production

AbstractTo evaluate agreement between flock-based fear tests used in welfare assessments of laying hens in commercial organic farms, three tests were applied in 27 flocks of layers. Tests were performed at 35 and 55 weeks of age and were based on the concepts of ‘novel object’, ‘sudden sound’ and two different measures of ‘approaching human’. In general, agreements between tests were poor. The two measures based on ‘approaching human’ had the highest agreement, while the agreement between all other flock-based tests were lower. There was low agreement between testing at age 35 and 55 weeks.In order to evaluate the degree to which the flock-based fear tests reflect individual hens' underlying fearfulness; tonic immobility (TI) tests were also applied on individual hens in eight flocks. There was large individual variation in the duration of tonic immobility, but also significant difference between flocks regarding mean duration of immobilisation. However there was no statistically significant association between TI-tests and flock-based tests. These results emphasise the need for careful consideration of choice of test stimuli for flock-based fear tests, and indicate that the investigated flock-based fear tests do not reflect the individual hens' underlying fearfulness.

Developing a HACCP-like system for improving animal health and welfare in organic egg production – based on an expert panel analysis

In the process of developing a generic Hazard Analysis and Critical Control Point (HACCP)-like system for securing animal health and welfare in organic egg production, an expert panel analysis was used to perform the initial hazard analysis. Eighteen advisers and researchers in organic egg production were included in the expert panel. In a series of four questionnaires, the expert panel first scored 34 health and welfare problems seen in Danish organic egg production. Based on scorings of severity and occurrence, 10 problems were selected for further analysis. The experts subsequently suggested and scored risk factors for those problems and finally suggested control points, alarm values indicating the need for corrective actions in order to control the risk factors and monitoring frequencies of these. The 10 selected problems were hunger, thirst, piling, crop impaction, blackhead, pasteurellosis, bone fractures, cannibalism, predators and red mites. A total of 154 different risk factors were suggested for these problems. The 41 risk factors which rated highest in a combined scoring of importance and occurrence were selected for further analysis. There was a high degree of consensus between experts when scoring both problems and risk factors. The level of consensus, as defined by an interquartile range ⩽1, was 79% to 100% when scoring the health and welfare problems (scale 1–5) and 77% to 95% when scoring the risk factors (scale 1–4). On average, 5.8 control points were suggested for every risk factor. Alarm values were often not detailed enough to be of practical significance and further analysis is needed in order to define these. The experts were highly diverse in their suggested monitoring frequencies and establishment of monitoring schemes should be part of developing the farm specific systems. An expert panel analysis based on questionnaires was a useful tool during the first steps of developing a HACCP plan, conducting a hazard analysis and suggesting control points. However, care should be taken regarding the panel’s size and fields of expertise in order to assure that the panel fully covers the field of interest throughout the study. A further development of the hazard analysis into a farm-specific HACCP system would include assembling an on-farm HACCP team consisting of farmers and advisors for the practical application of control points, alarm values and monitoring schemes. The results from the fourth questionnaire would be useful as input for this work.

Whole wheat versus mixed layer diet as supplementary feed to layers foraging a sequence of different forage crops

In many cases health and welfare problems are observed in organic egg production systems, as are high environmental risks related to nutrient leaching. These disadvantages might be reduced if the layers are allowed to utilise their ability to forage to a higher degree thereby reducing the import of nutrients into the system and stimulating the hens to perform a natural behaviour. However, very little is known about the ability of modern high-producing layers to take advantage of foraging to cover their nutritional needs, and the aim of the present work was to clarify this subject. Six flocks, each of 26 hens and one cock, were moved regularly in a rotation between different forage crops for a period of 130 days. Half of the flocks were fed typical layer feed for organic layers and half were fed whole wheat. The forage crops consisted of grass/clover, pea/vetch/oats, lupin and quinoa. At the beginning of the experiment, wheat-fed hens had a lower intake of supplementary feed (wheat) and a lower laying rate, egg weight and body weight. However, after a period of 6 to 7 weeks, the intake of wheat increased to approximately 100 g per hen per day and the laying rate increased to the same level as for the hens fed layer feed. For both groups of hens egg weight and body weight increased during the remaining part of the experiment. Crop analysis revealed different food preferences for hens fed layer feed and wheat-fed hens. Wheat-fed hens ate less of the cultivated seeds, whereas the amounts of plant material, oyster shells, insoluble grit stone and soil were larger in the crops from wheat-fed hens. Floor eggs were significantly more frequent in the hens fed layer feed, whereas wheat-fed hens only rarely laid floor eggs. Irrespective of treatment, hens were found to have excellent health and welfare. We conclude that nutrient-restricted, high-producing organic layers are capable of finding and utilising considerable amounts of different feed items from a cultivated foraging area without negative effects on their health and welfare.

Welfare and productivity of laying hens in commercial organic egg production systems in Denmark

Plumage condition, use of outdoor run, mortality and productivity were recorded in 18 Danish commercial organic egg-producing flocks consisting of 1200–5000 hens each. Between 7 and 38% of the hens in a flock used the outdoor run, with a mean of 18%. In most flocks the majority of the hens outside stayed close to the hen house, but some farmers succeeded in attracting the hens away from the house, which reduced the percentage of hens staying close to the house to 15%. At the age of 56 weeks, six flocks had little or no plumage damage, whereas four flocks showed severe feather pecking, but here feather pecking was already evident at an age of 28 weeks. Plumage condition was not significantly correlated with use of the outdoor run. The range in mortality rate amongst flocks was 9–62%, with an average of 22%. The high mortality was partly due to outbreaks of Pasteurella, mortality reaching over 50% in two of the four afflicted flocks. In some flocks also predatory attacks and piling (causing suffocation of the lowest birds) caused mortality. Average egg production was better than reported for Danish organic and free-range non-organic farms, but feed consumption and feed conversion rate were slightly higher. The results of this study do not provide a definite answer to the question whether or not hens should be kept outside.

Development of organic egg production and marketing in the EU

Egg production in the EU (15) increased by 12.2% over the last decade. In 2003 it reached a volume of 96.4 billion pieces. The leading countries in shell egg production are Spain with a share of 20.1%, France and Italy with a share of 17% respectively 14%. The self-sufficiency rate for eggs shows a great variety in the EU. In 2003, The Netherlands had the highest surplus with a rate of 175%, whereas Germany showed the highest deficit with a self-sufficiency rate of only 71%. Shell eggs are traded mostly within the common market of the EU. The Netherlands is the leading exporting country; Germany is the leading importing country.Organic egg production has also increased continuously over the last decade, without, however, reaching higher market shares. The contribution of organic egg production differs considerably among EU member states. Denmark has the highest share, followed by Austria and the United Kingdom; on the other hand, in southern European countries, organic egg production only plays a minor role. In spite of the increasing production volume, trade with organic eggs is still relatively unimportant in the EU.The new EU directive for laying hen husbandry and the new German directive will have far reaching impacts on egg production and egg trade in the EU. Due to the banning of conventional cages from 2007 on in Germany the amount of alternative egg production will increase dramatically in this country, but it is a still open question if the consumers will buy these more expensive eggs. The self-sufficiency rate for eggs will decrease from 71% to about 35% and force Germany to import about 10 billion shell eggs per year or about two thirds of all eggs that are being traded on the world market.

Use of the range area in organic egg production systems: effect of climatic factors, flock size, age and artificial cover

1. To evaluate the effect of climate, flock size, age and artificial cover on the use of range area, a study was conducted in 1994 to 1998, involving 5 farms with a total of 37 flocks of layers kept in commercial, free-range, organic systems. Flocks were visited regularly during the production period to record the number and distribution of hens on the range. 2. On average 9% of the flock used the range area, but with large variations both within and between flocks, and this was partly influenced by climatic factors. Range use was affected by temperature, wind, precipitation, season and age, and there was a tendency for reduced numbers of hens on the range with the time of day and increasing flock size. 3. Eight flocks (including houses and range areas) were divided into 8 paired units, and the range area of one unit in each of the flocks was provided with artificial cover. There were more hens on the range when artificial cover was present and the presence of cover attracted more hens away from the area immediately outside the hen house.