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Detailed studies have been carried out in humans into the affect dust has on the body, whether the source be work or home environment. Recently the trend has moved into the affect that dust in the animal houses has for animals. Equine research has taken place into the affect of dust on the horse's respiratory system. Respirable dust content is particularly applicable where horses have underlying health problems such RAO and IAD. In these situations the amounts of dust in the air can have serious implication to the equines well-being.
What is dust?
Dust is matter that can be found universally. The components the dust is made up of vary from setting to setting. The dust found in equine stabling will differ from dust in other mammalian bedding. In the stable setting the main sources of dust tend to be from the bedding and feed. Robinson and Sprayberry (2009), say that airborne dust concentration is determined by the ventilation, feedstuff and bedding, and level of activity.
There seems to be a general agreement that stable dust is a mixture of organic material including bacteria, bacterial and fungal toxins and spores ,also pollen, feed and animal components,( Cargill,1999 and Chroiniere and Munroe ,1999). Chroiniere and Munroe add that 70-90 % of this dust is organic. Elfman et al (2008), argue that this actual percentage of organic dust found in a stable is likely to be closer to be 60-70%.Elfman et al (2008), also add that Respirable Dust Content (RDC),is made up mainly of bacterial and fungal spore. Barn dust is high in dust from dander, animal hair , hay, manure and silica from indoor arenas .(Robinson and Sprayberry,2009).
Previous studies conflict in their findings of which bedding creates the most dust, Ward, Wohlt and Katz (2001) found that there were more airborne particles in wood shavings (WS) than the other two types of bedding these being straw(S) and pelleted newspaper (PN). In 1993, Woods et al however found in trials that straw bedding produced more airborne particles than stables bedded with wood shavings. Some confusion exists on exactly which beddings are most dusty. The incompatibilities of the above mentioned studies could be explained by the individual properties and processing of the bedding samples, i.e. where it was stored, how it was made and its overall quality.
Forage also is major contributor of the RDC in a stable. The main forages used in stables are hay and haylage. The quality and dustiness of the forage normally quantified by its source, processing, storage and age. Hay is generally regarded as the dustiest of forages (Robinson and Sprayberry, 2009).However the dust created by good quality hay is different in make-up to mouldy hay but both may produce mal-effects in equines.
Clements and Pirie (2006), show that a change from a hay to haylage forage type resulted in a 71-82% reduction of RDC in the breathing zone. Changes in the forage type used in a stable may greatly reduce or increase the amount of dust found there.
Total Dust and Respirable Dust Content (RDC)-
Total dust is the un-respired and respired dust as a whole. Total dust is measured in mg/m³. The recommended total dust levels in animal housing is 0.5 -1mg/m³ .Levels of dust above 2mg/m³ are recognized as too high.(Robinson and Sprayberry,2009).However no other published precise recommendations in regards to allowable environmental exposure in equine housing exist currently. Nor has recognised threshold that has been associated with airway disease in the horse been published.
The definition of Respirable Dust Content (RDC) is disputed by several sources. The British Medical Research Council (BMRC) says that this dust is that which penetrates the air spaces which are non-ciliated. This definition however does not take into account airborne dust which is responsible for bronchial lesions, upper airway disorders or occupational bronchitis. However other sources such as the Health Effects Research Laboratory (HERL) of The U.S. Environmental Protection Agency (EPA), suggests that a more fitting definition of RDC is the fraction of inspirable dust which can reach into a healthy trachea in inspiration. Likewise Lippmann (1970) ascertains that RDC is the small portion of dust which is airborne and reaches the peripheral airways.
The Breathing zone is the area in and around the nose. RDC is best measured in the breathing zone. Measurement by attaching the apparatus to a stall wall, or in an aisle can yield very different results to in the stable. Since the aisle does not take into account the bedding or feed, since it typically is not kept there. This is correlated by Robinson and Sprayberry (2009),where studies showed that horses bedded on straw and fed hay had a total dust count of 2-9 times higher than Respirable dust. In another study it was shown that the concentration of particles around the nose could be 8 times higher than in the air or in the nose. Horses spend a lot of time with their noses near forage or bedding. It stands to reason that the most reliable measurements should come from the breathing zone. Measurements for the Breathing zone can be done by having the apparatus for measurement attached near the breathing zone or in the breathing zone
Endotoxins and Molds:
Enodtoxins are the liposachharide component of the cell wall of gram negative bacteria
Endotoxins cause pulmonary neutrophilia in both RAO affected and non-affected animals .It proves a strong risk factor for the development of IAD.
Endotoxins in samples of air have been linked to several diseases including RAO.Robinson and Sprayberry (2009), write that endotoxin levels found in the breathing zone of horses fed hay and bedded on hay were as high as 1-2g ng/mg .At these levels airway inflammation and lung dysfunction in RAO susceptible horses were common.
Physiology of the Equine
The horse is equipped with numerous defences against airborne foreign bodies. The first line of defence for equines is the nostrils. The majority of inspired air is drawn through the nostrils, rather than the mouth. The nostrils can open and close readily, thus controlling to a degree what the horse inhales. In addition, the hairs on the inside of the nostrils help filter out debris.
Moist mucous membranes that collect foreign material line the various twists and turns of the upper airways. The design of these nasal passages maximizes airflow contact with the mucous membranes. Not only do these membranes collect debris, but they also help to regulate the inhaled air's temperature and humidity. Once debris is captured on the mucous membranes, nasal secretions (runny nose) or a sneeze will remove it.
As an important secondary protection, these membranes involve neutrophils to attack any foreign body. These white blood cells and other inflammatory mechanisms destroy bacteria and viruses and engulf small particles. The membranes become swollen and irritated.
Sometimes an allergic reaction to dust and mould can occur, resulting a chronic rhinitis. The end result is a swollen, inflamed nasal passage. This is irritating to the horse but more importantly, the combination of swelling, inflammation and thick secretions increases air flow resistance, which can lead to poor performance.
There is a limit to the filtering capabilities of these nasal passages, and any missed dust or debris will pass into the large airways leading to the lungs (tracheal and bronchial tubes). This debris and secretions will be sneezed out or swallowed. The tracheal and bronchial membranes can also call on cellular defence mechanisms to help fight airborne bacteria and viruses.
These cellular reactions are important, but like the mucous membranes in the nose, the airways will fill with fluid and mucous. This further complicates the athletic horse's ability to breathe properly.
Any debris that escapes the primary airways will end up deep in the lungs, causing further problems. The lungs will constrict with inflammation. (Rush and Mair 2004, p189).
Control of breathing comes from the medulla oblongata in the form the respiratory motor neurons. These motor neurons discharge in steady pattern .The information received by these neurons comes from multiple sources in health and disease.
Healthy, functioning lung parenchyma should contain a complex weave of elastin and collagen within the alveolar wall. The inner elastic recoil of the lungs is stabilized by resistance in the inward wall. At low lung volumes the fibres in the lung are easily inflated, however as the lung fills with air these fibres become increasingly rigid. These fibres are located evenly over the parenchyma .The fibres pull on the small airway walls ensuring that the airway remains open and unobstructed. These airways are however narrow in diameter even in exhalation since alveoli surround them at a much higher pressure. (Colledge et al 2010)
The type of bedding employed in the stable can be a huge factor in how dusty an equine environment can be. However with every bedding, comes a cost whether it be in monetary or time.
Straw is still a widely used bedding type. It has a clean, bright appearance and in a good harvest year it can be very cheap. Straw is warm and secure for foals and young stock and can help reduce the risk of an animal becoming cast. Any straw that is of high quality is likely to be eaten by the horse this can make a common horse fat or affect the fitness of horses in fast work.
Straw can prove a source of dust and fungal spores , however when using the deep litter method of mucking out less spores are released into the atmosphere as there is less disturbance of the bed. It can be relatively easily disposed of however the manure is heavy to move out whilst mucking out.
Wheat straw has a short stalk and when it is compacted it can be brittle, reducing its durability and therefore reducing its value as bedding. Good wheat straw however makes excellent bedding since it is thick and not particularly palatable.
Barley straw tends to be longer and of better quality than wheat straw. It also has the brightest colour out of the three straw types. Modern combine harvesting removes the awns which were a possible cause of irritation of the skin .However barley straw is palatable to horses and therefore can be expensive.
Oat straw is expensive and highly palatable .It quickly becomes saturated and is the least suitable for bedding.
Shavings and Sawdust-
Shavings are either baled or delivered directly from merchants. Shavings are widely believed to be less dusty than sawdust. These beds tend to be spore-free and unpalatable. However samples may be dusty and require dampening down .
Dust extracted Shavings-
Dust extracted shavings are the most popular as they are of a higher quality and have a low dust content. Low quality shavings, often a sawmill by-product are not suitable for horse bedding as they can be contaminated with sharp splinters and other potentially dangerous waste. The brands of shaving with the largest flakes are usually produced from virgin wood and can have lower dust content. Shavings are very light and tend to blow around the stable and yard and stick to tails and rugs. Wood shavings do provide excellent support for the horses' hooves as they compact inside them. This type of bedding is also very good for deep litter management systems. Shavings are usually packed in polythene wrapped bales making them easy to stack and store.
Shredded wood fibre-
Shredded wood fibre is a relatively new and unique product, specifically manufactured from selected recycled white wood, making it one of the 'greenest' bedding products. This product is totally dust free and absorbent which helps to keep the surface of the bed dry. This type of bedding is less likely to move around, so may help to reduce the risk of injury when the horse gets up and lies down. The quality of shredded wood fibre is of a consistently high quality and it is widely available. Shredded wood fibre offers support to the hooves and is easy to manage with very little waste, so producing one of the smallest muck heaps. It does not tend to stick to tails and rugs as much as wood shavings and packaging is designed for the product to be kept outside.
Paper and Cardboard:
Paper is usually shredded and consists of a mix of newspaper, and other unwanted printed matter, with varying absorbency. Paper is a dust free and non-palatable bedding material that is easy to muck out depending on whether the paper is cut in to long strips or short flakes. The long strips tend to be harder to muck out and it is difficult to separate the droppings. Bales usually come wrapped in polythene making them easy to store. Paper is one of the cheaper types of bedding, but a large number of bales may be needed to create a thick bed. Ink can also stain a light coloured coat. Paper becomes hard to manage and very soggy when allowed to become wet.
Cardboard like paper is usually shredded and is another dust free bedding material. It can however move around the stable like paper, leaving bare patches when the horse gets up and lies down. Cardboard clumps together when wet making removal of theses patches easy, but it can be difficult to separate from droppings, which can be wasteful.
Robinson and Sprayberry (2009) , have suggested that moistened paper or cardboard is significantly less dusty than shavings or straw.
Rubber matting is becoming a very popular product for use on its own or with other bedding materials. Rubber matting provides excellent support for the horse's hooves and limbs and minimises the risk of injury as it covers the concrete floor, and provides better grip. Rubber flooring comes in separate mats that may interlock, or it can come in a liquid that forms a seamless floor that does not have to be lifted for cleaning. Rubber matting is most commonly used under a bedding material. A small amount of bedding material is often added on top of the mats, which helps soak up urine and contain droppings. Rubber matting can be used with any sort of bedding and is sometimes just placed at the front of the stable by the door for the horse to stand on. Some people choose to use rubber matting without any bedding however this option can lead to wet floors and dirty rugs and horses. Hygiene standards need to be high and the mats will need to be cleaned underneath to prevent a build up of ammonia. Rubber matting is easy to manage and although the initial cost is high, the amount of bedding used can be greatly reduced, saving time mucking out and reducing the size of the muckheap
Mucking out Regime:
How a stable is mucked out can greatly affect the amount of dust in the environment whether it be total or Respirable .The most common method of mucking out is by pitching the mixed manure and bedding against the wall of the stall and thus allowing the manure(which is heavier) to stay by the wall. The light bedding falls away back into centre of the stall. Whilst this is a time and cost effective way of keeping the stable clean Robinson and Sprayberry (2009),question is this method costing our horses respiratory systems? Although stables are generally mucked out and swept without their equine occupants , a significant RDC cloud is created. The adoption of more deep litter bedding in horse stabling therefore is a consideration .Less mucking out and disturbance of the bedding results in less dust. Deep litter bedding may help to alleviate RAO symptoms in animals.
Disorders associated with Dust:
Several problems in equines can be associated with dust. Behavioural problems have been identified in animals. Equines with dust in the nasal cavities have been witnessed showing discomfort, causing them to become headshakers, head-shy and to sneeze and excessively snort. Robinson and Sprayberry (2009), note that the excessive amounts of dust in the nostrils can cause an animal with a hypersensitive nasal nerve to headshake further. Headshaking attributed to particulate dust is often alleviated with a nose mask. The nose mask acts a filter, prevents as large amounts of particulates entering the nasal cavity.
Wathes et al (1983) commented on the aggressive behaviour exhibited by cattle, pigs and broiler chicken when they were kept in the poorly ventilated versus the well-ventilated sheds. Smith et al (1983) also commented on livestock actively avoiding the more dusty areas of the sheds, and preferring to spend more of their time in well ventilated areas.
Upper Airway Disease:
Equines are commonly affected by non-infectious Respiratory diseases. These being: Recurrent Airway Obstruction (RAO) and Inflammatory Airway disease (IAD).The risk factors for airway disease are: the amount of dust in the environment, size distribution of the dust particles, the composition of the dust and the horses genetic susceptibility to airway disease.
Recurrent Airway Obstruction (RAO)
Recurrent Airway Obstruction (RAO) has been known as several other names. It also has commonly referred to by the symptoms that are presented (heaves, broken-wind, Chronic Obstructive Pulmonary Disease (COPD)), or by the probable cause (allergic airway disease, hay sickness).Marlin and Nankervis (2002), say that RAO is the most common occurring medical condition in adult equines .Kobluk (1995) said that even mild obstruction caused by the appearance of dust in a horse with RAO can be major inhibitor of performance. RAO is of a serious concern to the performance and welfare of an animal but also from a monetary concern to the industry.
RAO is an inflammation of the distal airways. It is a hypersensitive allergic response to certain components of dust. The activation of the disease is a specific inflammatory response to the inspired pro-inflammatory agents (molds, endotoxins and noxious gases) present in the breathing zone of stabled horses. RAO is most commonly observed in horses that are stabled and fed hay. The condition generally can be reversed by housing affected horses in a dust-free stable. Robinson (2010) writes of studies carried out in the U.S., where symptomatic equines were moved from mid-western to central U.S.A and became completely asymptomatic even when exposed to locally grown and produced mould hay. This leads us to the conclusion that RAO is caused by the environment and its variables in which the animal is in. However for chronic sufferers of the disease the only real solution is to keep the animal out of the dusty environment, that is at pasture.(McGorum, Dixon and Robinson)
Minutes after exposure to the allergen, cells bearing the allergen specific IgE ( mainly being mast cells through the activation of FCER1 receptors) begin to work . When these mast cells start working several biological processes begin associated with the narrowing of the airway lumen occur. Mucous is secreted, vasodilation and microvascular leakage occurs and the smooth airway muscle begins to contract. IgE mediated mast cell degranulation in RAO can be tested with the positive passive cutaneous anaphylaxis test and sera from chronic equine sufferers (Eyre,1972). However the symptoms of RAO do not occur over short period of time. It can take days or hours for the coughing to start and airway obstruction to ensue. Therefore early phase response is not typically a clinical feature of RAO.
The Late phase(type 3 hypersensitivity response) of the allergic response is generally regarded as over a 6-9 hours after exposure to the allergen .Here the T -cells are influential in the response ,where neutrophils are alerted and obstruction of the airway begins.RAO also can be attributed to type 3 hypersensitivity reactions .The reactions are to inhaled allergens. The complement system is activated from the local pulmonary deposition and immune complex.
The role of certain bacteria in RAO also is of note. Faenta rectivirgula ,Aspirgillus fumigatus and thermogactinomyces vulgaris are also abundant in poor quality hay.(woods et al ,1993).The inhalation of these particular bacteriums caused airway obstruction in animals with RAO but not in control animals (McPherson et al 1979).Several sources point to these bacteria being culprits of inflammatory irritation. Franchini et al (1998) found that RAO affected equines in studies developed lumps under the skin when serum with antibodies to F.rectivirgula was injected subcutaneously. Robinson (2001) ,concluded that that RAO was not truly due to the neuromuscular control mechanisms or the anatomy of the airway but more likely due to the environment.
Summer pasture associated obstructive pulmonary disease (SPAOD) is a related form of RAO. It however normally occurs solely in warm humid weather weather. SPAOD is linked to dust and pollens the horse is exposed to. Like RAO the disease is related to allergens though an animal in this case is better off stabled inside top avoid the allergen which is more than often pollen. SPAOD was primarily seen in the U.S. however the disease is becoming more and more common in the U.K.
Inflammatory Airway Disease
Inflammatory Airway disease( also known as Lower respiratory tract inflammation (LRTI)and Small Airway inflammatory disease), like RAO is of significant note to the performance of animal. Robinson and Sprayberry (2009), write that it compromises the integrity of the airway. Resistance is created in the airway very easily with any small obstruction.
The symptoms of the disease are a chronic cough and a viscous ,pungent nasal discharge.IAD has been linked to several causes one of these being deep inhalation of particulates and atmospheric pollutants. Mucous is produced in response to the foreign bodies and the airway diameter is greatly reduced.
To diagnose the disease, Bronchoalveolar Lavage (BAL), can be carried out. Eosinophilic BAL fluid (5-40% of total cells),mixed inflammation with high total nucleated cells, mild neutrophilia(15%of total cells) , and increased metachromatic cells(mast cells>2% of total cells ) may point to IAD. However high levels of eosinophils may also indicate parasitic pulmonary disease and this should be first ruled out, before a full diagnosis can be made.
The treatment of IAD depends greatly in the results of the BAL and what it is specifically caused by. Mixed Inflammation can be treated with low dose natural interferon alpha, thus reducing inflammation. Where high numbers of eosinophils are identified, aerosolized corticosteroid is recommended. With elevated metachromatic cells, aerosol administration of sodium cromoglycate (200ug/day ) is recommended.(Rush and Mair,2004)
Human problems with dust:
Studies have been undertaken to better understand the relationship between respiratory problems associated with dusty environments and humans. This research has taken place particularly in work environments. Employers have a responsibility for their employees and therefore have a responsibility towards keeping the working conditions as healthy as possible .One of these conditions being keeping dust exposure levels down.
In the hemp manufacturing industry, Fishwick et al in (2001) reported that sweeping the floor produced the highest levels of total dust, protein, endotoxin bacteria and fungi in workers with hemp. Hemp workers often suffered from a tight chest on their first day and the first day back after a holiday whilst working in this dust environment.
In the equine industry, Elfman et al (2008), reported that 4 of 13 workers reported signs of dust related disorders. Two of the four showed signs of bronchial obstruction and the other two of the four affected showed evidence of related airway symptoms, even though the total and respirable levels of dust were well below the upper acceptable levels.
Guidelines for no-effect to be shown in humans with history of asthma or atopy are 2000 EU/m³for toxic pneumonitis, for airway inflammation 100 EU/m³ and for systemic effects also 100EU/m³. Respiratory problems were reported in workers with an organic dust exposure level as low as 90-115 EU/m³. (Fishwick et al, 2001)The figures reported by Fishwick et al (2001) suggest that the before quoted figures by Rylander (2007) may not be as accurate as before thought.
Horses in Ireland are generally confined to a stable at night and often for 24hrs of the day for the months of October thorough to March, depending on weather conditions for the year, individual constitution of the animal and occupation of the animal. The recommended stable size for a 16.2 animal is a stable which measures 12ft x 12ft, with a roof height of 1600 ft in stalls in loose-outside boxes, in barn stabling 2000ft, and in stables of 1000 ft each. In American barn stabling, a 12ft passageway should be left (Auty 2003). The horse's living space often is smaller than the recommended. This means that in this confined space the breathing zone of the animal is limited. Breathing zone is the horse's immediate environment.(Kobluk et al1995)
Good design should allow for efficient ventilation, thus providing a clean fresh exchange of air in the stabling(Ambrosiano and Harcourt 1997).The whole barn not just the aisle should be airy, this includes the stalls.
Good ventilation can help to minimise the amount of dust in a stable. There are two types of ventilation: Natural and artificial .
(1)- Natural Ventilation:
Natural ventilation is where wind and natural buoyancy are the natural forces that drive ventilation .Natural ventilation is measured in air changes per hour (ACH). An air change per hour is the total volume of the air replaced in the stable in an hour's time. (Wheeler 2006).
Wheeler (2006) said that 4 -8 air changes per hour be provided in stabling to reduce mould spore contamination, minimize condensation and reduce moisture and dust in a stable setting. The prevention of dust build-up in the stable is linked to good stable design.Natural ventilation in the form of planned ventilation is easiest to use, this can be in the form of correctly spaced doors and adding cupolas or vents where necessary. The stable should allow fresh air to gain access to the stable and stale air to exit the stable. An open, unobstructed interior gets fresh air into the horses and provides a outlet for stale air (Wheeler 2006).To ensure that good airflow is achieved hot air must rise, which in turn can pull cold air to the floor level and spread a cool fresh breeze.(Ambrosiano and Harcourt 1997)
In winter when openings tend to be closed the Total Dust Content in the stable is higher this inhibits the natural ventilation in the stable. Windy conditions however do improve stable ventilation.
(2) Artificial/Mechanical ventilation-
Artificial/mechanical ventilation is the movement of air using mechanical/ artificial methods , this could be in the form of fans, inlets and controls in a pressure -controlled structure. Mechanical ventilation is expensive to both install and maintain but makes it easier to control air quality and movement in the stable. Due to its cost it is not commonly used in an equine context.
Other considerations in reducing dust in the stable include keeping hay away from the stables. If hay is kept overhead Robinson and Sprayberry(2009) suggest that a tarpaulin be used underneath to prevent dust falling on the stalls and equine below. Leaf-blowing and vigorous sweeping of the aisles also contribute to creating a significant cloud of lasting dust. It is suggested by Rush and Mair(2004) that if the aisle is very dry it should be sprinkled with water to help stop excessive amounts of dust being airborne.
From the Literature it can be ascertained that dust both total and Respirable dust is of serious concern for the equine industry. Respirable dust is a problem for both equine and humans working in the environment and can be to huge detriment. While ventilation is a factor in how high or low the RDC is the best way to keep down the amounts of RDC down is to use bedding and forage that is low in dust. Robinson and Sprayberry (2009), ascertain this when they say that the best way to reduce dust in the stable is to use low dust feed and bedding.
Materials and Methods:
The Dusttrack Aerosol Monitor
The sampling in this experiment is done with a real time Dusttrack Aerosol Monitor. This was supplied by Environmental Monitoring Services Ltd (Dublin). The Dusttrack is commonly used in many indoor environments, these varying from industrial -office work places.
The Dusttrack Aerosol Monitor uses a laser-photometer .This laser measures and records the concentration of airborne dust. The monitor uses a pump which can draw air and air-particles thorough the inlet nozzle. The particulates which are drawn in are mixed with alcohol vapour and then this vapour is condensed to droplets. Flashes of light are produced when the vapour is passed through the laser .The flashes are counted by the photodector which can then ascertain the how particle rich the sample was.
Fig 2.1. The Dusttrack Aerosol Monitor
The Dusttrack Aerosol Monitor shows the user the real time concentrations in mg/m³ via a digital display screen. The monitor can be calibrated for use well before it is actually used and for when it is left unattended.
The dusttrack measures the respirable fraction of dust and operates at a flow rate of 1.7L per minute. The particle sample sizes can be up to 4µm. Any samples taken can analysed using a data analysis software .The information is logged into the memory of the dusttrack and then can be transferred to a P.C. The P.C. system also can be used to control remote and unattended sampling.
The equipment attached to the horse's back. This will be done by housing it in a steel cylinder in the middle of two anti-cast rollers.
It is held directly over the horse's back where a saddle would normally be positioned. Exhaust and ventilation holes are drilled in the side of the cylinder to create the correct working conditions for the dusttrack to work .Holes were also drilled to allow for tubing to run to the horse's head. This tubing is seven feet and runs from the monitor holder to the nose band of a head collar on the horse. The system is kept in place by aero board. Foam is used to keep the unit from mal-adjusting in position whilst mounted on the horses back.
The project takes place in Clonshire Equestrian Centre.
The research entails a week's trial before Christmas to familiarize the author with the equipment. This is a weeklong and tests the equipment in the environment in which it is be used. The actual experiment starts in January 2011. The proposed experiment starts on the 10th of January and will 18 days* with samples being taken every day for 8 hours (480 minutes).
Straw beds- Barley straw-3days
Wheat straw-3 days
Paper beds- paper-3 days
Shavings- Non-dust extracted-3 days
Dust extracted-3 days
Rubber with Minimal bedding- 3 days
Three day trial allows for changes in equine bedding to take place , i.e. soiling to take place of the bedding and allow any difference in the bedding adaptation to be measured.
One horse is used for taking the measurements. Four types of bedding are examined, these being paper, shavings, straw and rubber matting. Straw is divided into two types for measurement: wheat and barley .Shavings into dust extracted and normal shavings. Paper also is examined .With the rubber matting the minimal bedding is used during the measurement taking sessions. Each type of bedding is measured for three days. The horse will be fed hay as normal.