Fungi isolated from contaminated baled grass silage on farms in the Irish Midlands

The incidence of fungal growth on baled grass silage was recorded on 35 farms in the Irish Midlands in 2003. Fungal colonies were visible on 58 of 64 bales examined and the number of colonies per bale ranged from 1 to 12. On average, 5% of bale surface areas were affected. The fungus most prevalent on bales was Penicillium roqueforti, present on 86% of bales and representing 52% of all isolates. Other moulds isolated were Penicillium paneum, Geotrichum, Fusarium and mucoraceous species. Schizophyllum commune was observed protruding through the plastic film on bales on 17 of the 35 farms.     

Variations in bacterial communities in laboratory-scale and big bale silos assessed by fermentation products, colony counts and denaturing gradient gel electrophoresis profiles

Aims: To assess the variation in bacterial communities in laboratory‐scale and big bale silos. Methods and Results: Wilted Italian ryegrass (628 g dry matter kg^?1) was ensiled in vacuum‐packed plastic pouches and big bales. Silos were opened after 3 months, and the fermentation products, colony counts and denaturing gradient gel electrophoresis (DGGE) profiles were determined. Eight samples were collected separately from a big bale, while one representative sample was taken from a plastic pouch. Significant variation was found between big bales in dry matter, ethanol, lactic acid, acetic acid and ammonia‐N contents. No differences were shown between plastic pouches and big bales, except that more ethanol was produced in the former air‐tight silos. Plastic pouches could resemble a specific silo and outer sampling sites of big bales based on fermentation products and DGGE profiles respectively. Conclusions: Considerable variation in fermentation products may exist between big bale silos. Plastic pouches can serve as a model of big bale silos, although they do not provide information on the heterogeneity within and between bales. Significance and Impact of the Study: Assessment of bacterial communities associated with ensiling can differ according to the criteria of fermentation products, colony counts and DGGE profiles.     

Quantification and identification of fungal propagules in well-managed baled grass silage and in normal on-farm produced bales

The viable fungal spora of baled grass silage was quantified and identified. One group of bales (Experiment 1, n = 15) was wrapped in 6 layers of polythene, and was handled and stored for 6 weeks under well-managed conditions. This silage was free of visible fungal contamination after 6 weeks and the film surrounding these bales was visibly undamaged. Moulds were cultured from 9/15 bales, while yeasts were cultured from all bales. A second group of bales (Experiment 2, n = 18) from 9 farms, were wrapped in 4 layers of film, handled and stored for 8 months using normal on-farm procedures. Visible fungal contamination was observed on the surface of most of these bales (15/18) and the film surrounding some bales (8/18) was damaged. In silage sampled from parts of bales that were visually non-mouldy, yeasts were cultured from all bales and moulds from 15/18 bales. Bales in the well-managed group (Experiment 1) had numerically lower numbers of yeasts (mean: 9.7 × 10³ colony-forming units per gram of silage, cfu/g) and lower numbers of moulds (<10¹ cfu/g) compared to the normal on-farm produced group (2.3 × 10⁵ yeast and 1.5 × 10⁵ mould cfu/g; Experiment 2). The most common yeasts in each group of bales were Saccharomyces exiguus (12/15 bales; Experiment 1) and Pichia fermentans (11/18 bales; Experiment 2) and their numbers in all bales ranged from 0 to 10⁵ cfu/g (mean: 8.4 × 10³) and 0 to 1.5 × 10⁶ cfu/g (mean: 1.2 × 10⁵), respectively. Bales contaminated with visible mould growth on their surfaces had higher yeast and mould numbers in visually non-mouldy parts adjacent to the contaminated areas than bales that had no visible mould. Mould numbers were higher (P<0.05) in bales where the polythene film was visibly damaged compared to bales where the polythene film appeared intact. Penicillium roqueforti was not cultured from the well-managed bales, but it was the most common mould in bales prepared using normal on-farm procedures (13/18 bales); propagule numbers in bales ranged from 0 to 7.1 × 10⁵ (mean: 1 × 10⁵ cfu/g). Low numbers of mould propagules, the absence of viable P. roqueforti spores and the absence of mould growth in well-managed bales, emphasises the benefit of applying sufficient film and preventing it from becoming damaged during bale handling and storage.     

Optimal configuration and combination of multiple lignocellulosic biomass feedstocks delivery to a biorefinery

Biomass availability and transportation are major challenges in establishing a large-scale biorefinery. The objective of this study was to assess the delivery cost of different combinations of multiple forms of lignocellulosic feedstocks including agricultural and woody biomass. Three types of biomass i.e., wheat straw, corn stover and forest biomass were considered in different forms such as loose biomass, bales/bundles, chopped/chipped and pellets. It was found that the delivery cost of a combination of woody and agricultural biomass feedstocks is lower than that for a single type of biomass. The delivery of agricultural residues as bales and woody biomass as chips is an economically attractive option with optimal combination of 30% bales and 70% wood chips to a biorefinery of capacity 5000 dry tonnes per day. The anticipated traffic congestions resulting from biomass supply to a large facility could be significantly reduced by increasing the density of biomass.     

The influence of hay-packing techniques on the presence of Saccharopolyspora rectivirgula

Environmental factors influencing the growth, distribution and viability of thermophilic actinomycetes, especially Saccharopolyspora rectivirgula as an agent of extrinsic allergic alveolitis in farms workers, were studied. Total microbial count, eumycetes and thermophilic actinomycetes were determined on 96 hay samples, randomly collected, from small prismatic and large cylindrical bales, 30 air samples before and after animal feeding, and various surfaces in two farms located in the province of Reggio Emilia, Italy. The number of thermophilic actinomycetes (potentially responsible for hypersensitivity pneumonitis) was higher in hay samples from large cylindrical bales than in those from small prismatic bales. The structural characteristics of the buildings (barns with stalls, poor ventilation) and the feeding practices (manual handling of hay, constant presence of hay in feedings corridors) contributed to the dispersion of high levels of thermophilic actinomycetes spores (potentially responsible for extrinsic allergic alveolitis). The ventilation system proved to be inadequate in reducing the number of microorganisms present.     

Detecting the Seeds of Nassella neesiana in Large Round Hay Bales,by Means of Non-Destructive Core Sampling

In the last three decades or so there has been a significant increase in fodder trading, both in terms of the quantity of fodder traded and in terms of its economic value to the industry. Often, this fodder type may be supplied free of charge to graziers in distress due to circumstances that follow natural disasters such as bushfires, drought, and flood. However, because of the obvious urgency arising from these situations, it is suspected that much relief fodder may unintentionally pose an elevated risk for dispersal of weeds since it may be supplied from pasture not normally used for trade in fodder, and therefore is of unknown quality. Previous destructive method to detect weed propagules in bales of fodder are cumbersome, time consuming and of limited ecological and statistical value. Therefore, objective of this paper was to development of a convenient method to assess round pasture hay bales for the presence of weed propagules, to prevent unintentional spread of noxious species in hay bales. To examine this objective known quantity of seeds were added in a series of distributions to bales of seed free pasture hay, and a positive correlation for the amount of seed added per bale with that recovered in core samples was observed. Whilst the number of seeds detected per bale varied according to the distribution of seeds within the bales and the number of cores analysed, the absolute detection of seeds suggests that this sampling method is worthy of further examination. In addition, a pragmatic estimation of bale remnants after stock feeding has been investigated to more closely estimate the potential size of the remaining seed bank. The authors propose that development of this approach is timely, in the light of future climatic uncertainty driving extreme weather events that increase the need for relief fodder, which can be a potential vector for the spread of noxious weed seeds.     

Quarantine control of Hessian fly (Diptera: Cecidomyiidae) in exported hay: a new treatment for large-size, polypropylene fabric-wrapped bales and a 3-d fumigation for compressed standard bales

Hessian fly puparia (37,167), Mayetiola destructor (Say), did not survive a large-scale commercial test (three freight containers) of a new quarantine treatment using compression (32 kg/cm2) and hydrogen phosphide fumigation (61 g/28.2 m3) for large-size, polypropylene fabric-wrapped bales of hay exported to Japan. Mean +/- SEM temperatures in the large-size bales in different locations in the freight containers ranged from 18.0 +/- 0.9 to 26.0 +/- 1.3 degrees C during the 7-d test conducted in a heated building at 20.1 +/- 1.1 degrees C. Highest concentrations of hydrogen phosphide in most locations in the freight containers were observed after 3 d of fumigation and ranged from 366.7 +/- 96.1 to 425.0 +/- 162.7 ppm (mean +/- SEM) and throughout the 7 d of fumigation ranged from 253.6 +/- 59.9 to 407.1 +/- 76.5 ppm (mean +/- SEM). Hydrogen phosphide residues after fumigation and aeration were <10 ppb and were below the U.S. Environmental Protection Agency tolerance of 0.1 ppm in animal feeds. The results of the test fulfills regulatory agency testing requirements and confirms the efficacy of the treatment to control Hessian fly in large-size, polypropylene fabric-wrapped bales of hay. Hessian fly puparia (2,160) did not survive a large-scale commercial test of compression (105 kg/cm2) and a 3-d hydrogen phosphide (60 g/28.3 m3) fumigation for standard bales.     

Livestock Protection Dogs for Deterring Deer From Cattle and Feed

Abstract: Disease transmission between wildlife and livestock is a worldwide issue. Society needs better methods to prevent interspecies transmission to reduce disease risks. Producers have successfully used livestock protection dogs (LPDs) for thousands of years to reduce predation. We theorized that LPDs raised and bonded with cattle could be used to also reduce risk of bovine tuberculosis (Myobacterium bovis; TB) transmission between white-tailed deer (Odocoileus virginianus) and cattle by minimizing contact between the 2 species and use of cattle feed by deer. We evaluated 4 LPDs over 5 months, utilizing 2 data collection methods (direct observation and motion-activated video) on deer farms that supported higher densities than wild populations. Dogs were highly effective in preventing deer from using concentrated cattle feed (hay bales), likely the greatest risk factor of TB transmission on farms. Dogs also prevented deer from approaching cattle in core areas of pastures (near hay bales) and were very effective throughout pastures. Our research supports the theory that LPDs, specifically trained to remain with cattle, may be a practical tool to minimize potential for livestock to contract TB from infected deer in small-scale cattle operations. Where disease is present in deer, it may be possible to reduce the potential for disease transmission by employing LPDs.     

The feeding value for ruminants of straw and wholecrop barley and oats treated with anhydrous or aqueous ammonia or urea

Ammonia-treated or untreated barley straw supplemented with urea was given as the only feed to two groups of Friesian heifers weighing approximately 550 kg. The digestibility of dry matter (DM) was 58.8 and 49.9%, daily feed intake was 5.88 and 3.87 kg and daily liveweight change was +324 and -447 g for the ammonia-treated and control barley straw diets, respectively.Anhydrous or aqueous ammonia (NH₃) was injected into large round straw bales covered with plastic. The rates of degradation of barley straw in nylon bags and digestibility in vivo were the same for both ammonia treatments. The distribution of N in the bales was also similar and uniform with both treatments. No differences were recorded in the rate of degradation in nylon bags if the plastic was removed 2 or 8 weeks after treatment.Anhydrous or aqueous ammonia or isonitrogenous amounts of urea were injected into large round bags containing whole-crop barley or oats collected with a forage harvester. The digestibility of starch by steers was about 92% for ammonia-treated samples and 78% for the urea-treated samples. Urea and ammonia efficiently preserved the whole-crop materials but untreated control samples and samples treated with NaOH deteriorated during storage.     

A new method for restoring ditches in peatlands: ditch filling with fiber bales

Ditching is a common practice to dewater wetlands, including peatlands, and ditch blocking is a common method for restoring wetlands because substrate is often unavailable for filling the ditches. However, filling has many advantages compared to blocking ditches. Our goal was to test whether ditches could be filled in a Colorado sloping fen (Chattanooga Fen) using bales created from shredded aspen (Populus tremuloides) tree‐fiber. We monitored water table levels before and after we filled two ditches (combined length of approximately 165 m × 3 m wide) as well as an undisturbed reference portion of Chattanooga fen. The reference site had stable water tables that rarely dropped more than 20 cm below the soil surface. The ditches had been dewatering large areas of the fen for at least 100 years. Filling the ditches with fiber bales resulted in a water table increase between 2 and 22 cm in an area up to 150 m below the ditch. Native sedges now cover the area where we filled the ditches, with no erosion or compression/settling of the ground observed and no water backing up behind the filled ditches. Filling the ditches with shredded fiber bales is a good option for restoration in wilderness areas, or areas lacking peat or mineral soil fill because it is a natural material that is easily transported and placed in the ditches.     

Protein degradation in the rumen of red clover forage at various stages of growth and conserved as silage or wrapped big bales

In order to study the extent to which rumen soluble nitrogen can contribute to the intestinal flow, a study was carried out to simultaneously assess the dynamics of protein disappearance from dacron bags placed in the rumen and the amount of various N products in the rumen fluid (total nitrogen (tN), ammonia nitrogen (NH3-N), non-ammonia nitrogen (NAN)). The measurements were carried out on 4 sheep fed successively various red clover forages. These forages included the initial growth of fresh red clover (50% bud, first flower, and full flower). In addition, one silage and one wrapped big bale at the first flower stage and two wrapped big bales (harvested at 51% and 71% dry matter) at the full flower stage were given. The effective degradability of nitrogen (DegN) for a fresh forage estimated from the nylon bag procedure did not vary (p > 0.05) with the vegetation stage (0.727 for the bud stage, 0.694 at the first flower, 0.706 at the full flower). The DegN of the silage was higher (p < 0.05; 0.735) and the DegN of the wrapped big bale was markedly lower (p < 0.05; 0.660), than the original fresh forage at the first flower. The DegN of the wrapped big bales made at 51 and 71% DM, respectively, were 0.625 and 0.604 against 0.706 for fresh forage at the full flower stage. The concentrations of tN and NAN in the rumen fluid were low, highest 1 h to 2 h after feeding, and then decreasing up to 7 h after feeding whatever the growth stage and conservation mode. A part of the solubilised nitrogen remained as protein 1 h after feeding for fresh red clover harvested at various growth stages, while minimal protein could be seen in the rumen fluid after the sheep were fed silage or wrapped big bales. The part of NAN escaping rumen degradation and transiting with the rumen fluid was between 7 and 13% of the nitrogen disappearing from the nylon bags (NAN/CP x DegN) placed in the rumen. There was only a small difference for forages at different stages of growth, or modes of conservation. This fraction was higher for wrapped big bales and particularly for the late stage forage (wrapped big bale, 71% DM, harvested at the full flower stage).     

The effect of prolonged storage on the digestibility and nitrogen content of ammonia-treated barley straw

Barley straw in a 10-t stack was treated with anhydrous ammonia (40 kg t^?1 straw dry matter). Four bales, two buried in the stack and two with one face exposed, were sampled before treatment, at 54 days (1 day after the stack was first opened) and at regular intervals thereafter for a further 12 days. The total nitrogen content of the straw increased from the 6.7 g kg^?1 straw dry matter present before treatment to 20.7 g kg^?1 at day 54. Ammonia nitrogen contributed 7.4 g and non-ammonia nitrogen 6.6 g of this increase. There was a rapid loss of ammonia on opening the stack and this continued for the first week; thereafter ammonia was lost at a much slower rate. In all, 39% of the ammonia nitrogen present 1 day after opening was lost by the end of the sampling period. This loss accounted for the 18% reduction in total nitrogen recorded over the same period. Loss of nitrogen did not affect the digestibility of treated straw as determined by the nylon bag method using sheep. Digestibility, whether expressed as loss of dry matter or as digestibility of cellulose, remained constant throughout. Added water-insoluble nitrogen appeared to be more readily available than that initially present in untreated straw. The position of bales within the stack did not affect results significantly.     

Bale compression and hydrogen phosphide fumigation to control cereal leaf beetle (Coleoptera: Chrysomelidae) in exported rye straw

Control of larvae and adults of cereal leaf beetle, Oulema melanopus (L.), by bale compression and hydrogen phosphide fumigation was studied in rye straw, Secale cereale L., in Aurora, OR. Natural mortality of larvae after transport was 4.0 +/- 1.0% (mean +/- SEM). Compression (105 kg/cm2) of larvae in standard bales (122 cm long) of rye straw resulted in 100% mortality. Compression of adults in standard bales plus storage of the compressed bales (56 cm long) for 1 d in a freight container resulted in 100% mortality. A KD50 of 102 ppm hydrogen phosphide for 1 h was estimated from the probit regression line developed from dose-response data at 21 degrees C in basic laboratory tests. The LD50s and LD99s were 163 and 6,910 ppm for 2-h exposures and were 18 and 42 ppm for 6-h exposures at 21 degrees C, respectively. A tested close of 400 ppm for 24 h at 21 degrees C resulted in 100% mortality of the adults. Larvae (n = 10,560) and adults (n = 18,602) did not survive exposure to bale compression followed by hydrogen phosphide fumigation (60 g/28.3 m3) for 3 d in rye straw loaded in freight containers in large-scale tests. Copper plate corrosion values indicating the severity of exposure to hydrogen phosphide were 13 and 12, and mean temperatures of five locations in the freight container were 25 and 26 degrees C in large-scale tests with the larvae and adults, respectively. Hydrogen phosphide concentrations were > or = 400 ppm throughout the 3-d fumigation for larvae and during the first day of fumigation for adults. We propose that cereal leaf beetle can be controlled by a single treatment of bale compression followed by a 1-d storage period or by a fumigation in which 400 ppm hydrogen phosphide is maintained for 1 d at 21 degrees C or above. We confirmed that a multiple quarantine treatment of bale compression) followed by a 3-d fumigation will control cereal leafbeetle in exported rye straw.     

Approved quarantine treatment for Hessian fly (Diptera: Cecidomyiidae) in large-size hay bales and Hessian fly and cereal leaf beetle (Coleoptera: Chrysomelidae) control by bale compression

A quarantine treatment using bale compression (32 kg/cm2 pressure) and phosphine fumigation (61 g/28.3 m3 aluminum phosphide for 7 d at 20 degrees C) was approved to control Hessian fly, Mayetiola destructor (Say), in large-size, polypropylene fabric-wrapped bales exported from the western states to Japan. No Hessian fly puparia (45,366) survived to the adult stage in infested wheat, Triticum aestivum L., seedlings exposed to the treatment in a large-scale commercial test. Daily temperatures (mean +/- SEM) inside and among bales in three test freight containers were 17.8 +/- 0.2 front top, 17.0 +/- 0.2 front bottom, 17.3 +/- 0.2 middle bale, 15.7 +/- 0.3 middle air, 18.5 +/- 0.1 back top, and 18.1 +/- 0.1 degrees C back bottom, allowing the fumigation temperature to be established at > or = 20 degrees C. Mean fumigant concentrations ranged from 208 to 340 ppm during the first 3 d and ranged from 328 to 461 ppm after 7 d of fumigation. Copper plate corrosion values inside the doors, and in the middle of the large-size bales in all locations indicated moderate exposure to hydrogen phosphide (PH3). PH3 residues were below the U.S. Environmental Protection Agency tolerance of 0.1 ppm in animal feeds. The research was approved by Japan and U.S. regulatory agencies, and regulations were implemented on 20 May 2005. Compression in large-size bale compressors resulted in 3-3.6 and 0% survival of Hessian fly puparia and cereal leaf beetle, Oulema melanopus (L.), respectively. Bale compression can be used as a single treatment for cereal leaf beetle and as a component in a systems approach for quarantine control of Hessian fly.     

Simple and farmer-friendly bumblebee conservation: Straw bales as nest sites in agricultural landscapes

Many bumblebee species are declining due to a loss of semi-natural habitats in agricultural landscapes resulting in diminished forage and nest sites. Anecdotal experience indicates that bumblebees nest in straw bales, but scientific evidence is lacking. We spent 250 h screening for bumblebee nests in 1255 straw bales and ten straw stacks belonging to 58 farms in two intensively farmed Swedish regions and recorded nests, nest traffic, and straw characteristics. We supplemented the straw screening with screening of control areas, without straw, that were selected in similar environments as the areas with straw. We observed 45 bumblebee nests (including potential nests where a single bumblebee flew in or out of the straw) of eight species/species groups, including one red-listed, in or directly adjacent to the straw at 26 of the farms. Nests were mainly found in partly decayed straw and bales placed together. We found no nests in control areas. Based on our results, we suggest that straw can be used as an easy, cheap and efficient intervention to increase the availability of bumblebee nest sites in agricultural landscapes. Considering the costs and benefits of the alternatives, we conclude that straw addition has advantages over commercial bumblebee colonies for crop pollination purposes and over artificial nest boxes for conservation purposes.     

Winter feeding sites of hay in round bales as major developmental sites of Stomoxys calcitrans (Diptera: Muscidae) in pastures in spring and summer

The stable fly, Stomoxys calcitrans (L.), historically has been a pest of livestock in confined operations but seldom of animals on pastures or rangelands. In the past two decades, however, S. calcitrans has become a major pest of cattle and horses on pastures in the midwestern United States. Although there usually is an overabundance of diverse stable fly and house fly, Musca domestica L., larval habitats in confined livestock operations, no larval habitat for stable flies has been clearly identified in the pasture-range environment. Because the winter feeding of hay in round bales results in significant amounts of hay wastage that when mixed with manure, might develop into suitable larval habitats, this study evaluated these areas as developmental sites for the abundant stable flies in pastures. There was a trend for fly traps placed in the vicinity of hay feeding sites to catch more stable flies than those placed distant from these sites. Estimates of stable flies emerging from these sites ranged from 102 to 1225 flies per core sample (25 by 25 cm). The mean number of adult stable flies during May and June 2001 through 2004 correlated negatively with the average minimum temperatures during the preceding winter (November-February) but not with rainfall or temperatures during the spring. These results support the hypothesis that winter feeding sites of hay in round bales are the main source of stable flies in pastures.     

Effect of stover fraction and storage method on glucose production during enzymatic hydrolysis

One avenue for overcoming the economic challenges associated with the production of ethanol from renewable resources is to reduce the cost of the biomass feedstock. The balance between storage costs and benefits depend on the storage method and composition changes of individual stover fractions. Corn stover from bales stored inside and outside of a barn was separated into an interior and exterior layer after approximately 10 months of storage. The cobs, stalks, and leaves and husks were separated, dried, and ground through a 2 mm screen. Stover, sodium acetate (buffer), cellulase, and deionized water were added to 125 ml flasks. The mixture was held at 50 degrees C in an incubator and samples taken for glucose determination. The average glucose concentration after 60 h of hydrolysis from cobs, leaves and husks, and stalks was 10.5, 9.6, and 3.1 g/l, respectively. Cobs, leaves, and husks produced over 300% more glucose than stalks. Storage outside of the barn decreased the glucose production from individual stover components between 4% and 8%. The effect of stover fraction type on glucose production was significant, while the storage treatment effect was not significant. Fractionation of corn stover may be a method to increase the value of corn stover as a feedstock for glucose production.     

The role of local adaptation in the relationship between an endangered root hemiparasite Euphrasia rostkoviana, and its host, Agrostis capillaris

We experimentally studied the role of local adaptation and the co-evolutionary relationship between an annual, endangered root hemiparasite Euphrasia rostkoviana and its main host Agrostis capillaris. According to our hypothesis, the existence of local adaptation in hemiparasites should be observable in better hemiparasite performance when attached to A. capillaris hosts originating From Euphrasia populations. After one month of growth, the height and the number of leaves of hemiparasites were not affected by the origin of their hosts. The differences in growth were due to between population effects. The situation remained constant after three months. Hemiparasite biomass was not affected by the origin of the hosts. The percentage of hemiparasites surviving after one. two and three months was not affected by the origin of the hosts although there was a weak tendency towards better survival of hemiparasites with familiar hosts than with unfamiliar hosts. All variables used to measure hemiparasite performance during its complete life-cycle gave only limited support for the local adaptation hypothesis. Nevertheless, the familiar hosts suffered less from parasitism as indicated by their higher biomass after the experiment. This suggests that there may be some interactions between hemiparasites and their hosts based on their spatial population structure and common history as competitors.     

Effects of three stressors on vegetation in an oligohaline marsh

1. When multiple stressors have interactive effects they can lead to important changes in ecosystem function. We examined how three stressors affected the plant community in an oligohaline marsh in southeastern Louisiana, U.S.A. These stressors included herbivory (mostly by the introduced rodent Myocastor coypus ), disturbance (herbicide application) and nutrient enrichment (three levels of N–P–K fertilizer). Sampling was conducted six times over 4 years.
2. Recovery after disturbance was slow, such that after 26 months biomass in disturbed plots was 36% that of controls. Slow recovery appeared to be due to herbivory, as exclusion of herbivores for 14 months led to much more biomass compared to non-excluded plots. Exclusion did not, however, aid recovery of species richness; this recovery required 51 months in total.
3. Nutrient enrichment increased biomass by 41% and decreased species richness by c. 20% in later sampling periods. Decreased species richness was due primarily to a reduced ability of dominant species to co-exist (as determined with Hill's diversity number N1). Nutrient enrichment did not interact with the other treatments.
4. Disturbance favoured two grasses ( Echinochloa crus-galli and Leptochloa fascicularis ), while lack of disturbance favoured two herbs ( Sagittaria lancifolia and Polygonum punctatum ) and two vines ( Ipomoea sagittata and Cuscuta pentagona ). Nutrient enrichment positively affected abundance of two species ( C. pentagona and L. fascicularis ). Herbivory did not affect species composition.
5. The effect of one stressor (experimental disturbance) on plant biomass depended on the strength of another stressor (herbivory). Nutrient enrichment was also important in affecting the plant community, but only as a single stressor. All effects changed over time, and it was clear that to understand properly the effects of multiple stressors, long-term, manipulative field experiments are necessary.     

Influence of the provision of natural light and straw bales on activity levels and leg health in commercial broiler chickens

The aim of this study was to assess the effect of natural light and straw bales on activity levels and leg health in commercial broiler chickens. Houses containing ∼23 000 broiler chickens were assigned to one of four treatments in a 2 × 2 factorial design. Treatments involved two levels of access to natural light (NL) (present ‘+NL’, or absent ‘−NL’) and two levels of access to straw bales (SB) (present (30/house) ‘+SB’, or absent ‘−SB’). All houses were windowed and artificially lit, and windows were shuttered where appropriate. Treatments were applied in one of the two houses on each of the two farms, and were replicated over four production cycles. Behaviour was observed in 2 to 6 weeks of the cycle. This involved observations of general behaviour and activity, gait scores (0 (perfect) to 5 (unable to walk)) and latency to lie (measured in seconds from encouraging a bird to stand). Production performance and environmental parameters were also measured. Average daytime light intensity and UV levels in the +NL treatment were 85.2 lx and 3.37 μW/cm², respectively, and in the −NL treatment were 11.4 lx and 0 μW/cm², respectively. Litter moisture levels were lower with NL treatment (P < 0.05), but were not affected by SB (P > 0.05). The percentage of time spent lying was significantly reduced by the provision of NL (P < 0.01), but not by SB (P > 0.05). There were three-way interactions between NL, SB and bird age on the percentage of time spent in locomotion (P < 0.05) and idling (P < 0.05). Both treatment factors had inconsistent effects on these parameters across different weeks. Levels of preening, resting and aggressive behaviour were not affected by treatment (P > 0.05). There was an interaction between treatments in average gait scores, with higher scores in the −NL−SB treatment than in all other treatments, and higher in the −NL+SB treatment than in the +NL treatments (P < 0.001). Average latency to lie was significantly higher with NL (P < 0.001) and SB (P < 0.05). We conclude that environmental modifications have the potential to increase activity levels and improve the leg health of commercial broilers. The light environment appears to be particularly important in this respect.