Muscle is a tissue with a great plasticity due to the fact that it is composed of fibres having different contractile and metabolic properties. In horses, muscle metabolic responses to exercise are studied by taking biopsies from the gluteus medius muscle. Histochemical stains are used to identify slow contracting type I fibres and fast contracting type IIA and type IIB fibres and to evaluate fibre areas, capillary supply, oxidative capacity, glycogen and lipid content in a muscle. Biochemical analyses of substrates, metabolites and enzyme activities are performed either on a whole piece of muscle, on pools of fibres or on single fibres of identified type.

All fibres contain glycogen whereas lipid is mainly found in type I and type IIA fibres that have smaller cross–sectional areas and a higher oxidative capacity than type IIB fibres. Large variations can be seen in metabolic profile between and within fibre types. The most common muscular adaptation to training is an increase in oxidative capacity, capillary density and an increase in the type IIA/IIB ratio. The order of recruitment of fibres during most types of exercise is from type I to type IIA and type IIB.

The higher the intensity of exercise, the faster is the breakdown of glycogen. After racing (1640-2640m), and after high intense treadmill exercise, concentrations of lactate and inosine monophosphate (IMP) are increased in the muscle and concentrations of glycogen, adenosine triphosphate (ATP) and creatine phosphate (CP) decreased. Extremely low ATP and high IMP concentrations especially in some type II fibres are observed after racing.

After exercise of low intensity and long duration glycogen and triglyceride stores in muscle are utilised, amino acid metabolism is enhanced and protein degradation may occur. After submaximal treadmill exercise to fatigue and after endurance rides glycogen is degraded and depletion occurs mainly in type I and type IIA fibres.

Fibre type composition, substrate sources and differences in metabolic properties among fibres and the extent to which fibres are recruited are all factors that influence the metabolic responses of muscle to exercise. Biochemical analyses on whole muscle must be interpreted with caution since large variations in metabolic response to exercise occur among different fibres.

The skeletal musculature of the horse is highly developed and adapted to match the animal's athletic potential. More than half of a mature horse's body weight comprises skeletal muscle and the total muscle blood flow during maximal exercise represents 78% of total cardiac output. Exercise requires the co–ordinated application of many different body systems under the control of the nervous systems. Metabolites and oxygen reach skeletal muscle fibres via the respiratory, cardiovascular and haematological systems. The muscle fibres produce energy in the form of ATP that, via the contractile machinery, is converted into mechanical work. The structural arrangements of the musculoskeletal system provides the means with which to harness this energy to move the horse's limbs in a characteristic rhythmical pattern that is well established for each gait.

Equine skeletal muscle is considerably heterogeneous and this diversity reflects functional specialisation and is the basis of its adaptive plasticity. Cellular and molecular diversity of equine muscle and the response of this tissue to exercise and training have been studied extensively over the past 30 years.

In this chapter we will review how the principles of mechanics can be used to address scientific questions relating to equine performance and disease.

Performance can be defined in terms of fundamental qualities or at an applied level. Energetic efficiency, speed, acceleration, endurance capacity, stability, and manoeuvrability, are recognised as fundamental selection pressures in the evolution of terrestrial locomotion. These contribute individually or in combination to performance in a particular sport. Whereas the capacity to achieve the highest value of the outcome measure for a particular sport might be used as an overall measure of performance however, it is more useful for the purpose of scientific investigation to consider performance in terms of more fundamental quantities. The overall aim is generally to relate locomotor form (morphology), function (movement), and environmental factors to fundamental measures of performance.

Size (indicated by body mass) has an important effect on the form of the locomotor systems of terrestrial animals.

The ability to use oxygen during exercise is determined by a combination of the muscle mitochondrial density, the relative proportion of total body mass consisting of locomotory muscle, the gas exchange surface area and the capacity for conduction of oxygen from the gas exchange surface to the muscle cells, i.e. the heart and circulation. Other factors include: the ability to ventilate the lungs to ensure that a high gradient is maintained between the alveolar oxygen tension and that in the pulmonary capillaries to facilitate diffusion; the capillary density within muscle, the size of the muscle cells and the blood oxygen carrying capacity, which is primarily determined by the total blood volume and haemoglobin concentration.

In absolute terms, the fastest animal on land is the Cheetah, which can reach speeds of up to 120 kmh. However, the Cheetah is a “sprinter” and can only achieve these speeds for distances of around 200 metres (<10 seconds).

The commonality in neural mechanism (transmitter and brain region) underpinning stereotypy and that associated with motivation of goaldirected behaviours lends support to the idea that the former is derived from the latter. Hughes and Duncan postulated this theory behaviourally within their proposed 1988 model of motivation. This review re–interprets the Hughes and Duncan model to neurochemically describe the motivational development of stereotypic behaviour in the horse.

A review of physiology and behaviour–based studies on the function of stereotypic behaviour indicates contradiction and inconsistency within the literature. By considering appropriate neurochemical data alongside an existing model of motivation (Hughes and Duncan, 1988), a greater understanding of the function of stereotypy may be gained. The Hughes and Duncan model (1988), described stereotypies as highly motivated appetitive behaviours performed repeatedly in an environment where consummatory goals are denied. Moreover, appetitive behaviours activate reward circuitry such as the ventral tegmental area and nucleus accumbens and are thus considered to have a reward value associated with their performance (Carr, 2002; Jones et al., 1990). Stress induced sensitisation of reward circuitry may result in appetitive ‘stereotypies’ having increased reward value, perhaps becoming consummatory in their own right. In such a scenario, stereotypic behaviour could function as a coping tool, allowing the animal to counter the effects of an aversive environment.

Neutrophil elastase (NE), a powerful proteolytic enzyme found within the primary cytoplasmic granules of polymorphonuclear leukocytes (PMN), is capable of degrading almost any component of the extracellular pulmonary matrix and forms part of the cells’ armoury against invading microbes (Crystal, 1996; Haslett, Savill and Meagher, 1989). It is essential during inflammation for diapedesis and migration to extravascular compartments (Henson and Johnson, 1987), oxygen independent bactericidal activity and the remodelling of damaged tissues (Ganz, Metcalf, Gallin and Lehrer, 1987) and is crucial for health as an absence results in increased susceptibility to pyogenic infections which, if untreated, are eventually fatal. Mature PMN contain a finite amount of NE (Campbell, Silverman and Campbell, 1989) which can only be synthesized during development within the bone marrow, especially the pro–myelocyte stage (Fouret, duBois, Bernaudin, Takahashi, Ferrans and Crystal, 1989).

PMN are often the first white blood cells to be attracted to an inflamed and/or infected area within the body and can persist there due to their role in remodelling damaged tissue.

The application of modern breeding technologies to the practical breeding of horses has accelerated worldwide over the past two decades in all breeds and types of horses except the Thoroughbred. Artificial insemination (AI) with fresh extended semen is used routinely on most stud farms with considerable improvements in efficiency, fertility, disease control and management costs. The ability of cooled semen to retain high fertility for 24-48 hours enables its widescale shipment within and between countries by modern transport methods. Even the use of deep frozen semen is increasing rapidly, in conjunction with a single fixed–time insemination in relation to gonadotrophininduced ovulation. The wide scale use of the ultrasound scanner to monitor follicular development and ovulation has markedly improved diagnosis of the optimum insemination time, with consequent improvements in conception rates. However, repeated scanning examinations at intervals of only 4-6 hours in order to carry out insemination of frozen-thawed semen after, rather than before, ovulation is illogical and inefficient.

During the past eight years a comprehensive genetic linkage map for the horse has been generated in Newmarket, through a fruitful collaboration between the Genetics section at the AHT and Professor Twink Allen at the TBA Equine Fertility Unit (Swinburne et al., 2000). In order to assess whether the map was adequate to start mapping disease traits in which we are interested, it was decided to attempt to map a clear, easily scoreable trait such as grey coat colour in the Thoroughbred horse. Grey coat colour is inherited as an autosomal dominant trait. Thoroughbred horses are fairly inbred, and as such they represent one of the more difficult horse breeds for genetic mapping. The majority of grey Thoroughbreds trace their ancestry back to Allcock's Arabian who was born in 1700, and horsemen have long noted an association between grey coat colour and the incidence of melanomas. It is hoped that characterizing the mechanism of grey coat colour formation might also lead to an improved understanding of the molecular basis of melanoma formation.

In mammals the placenta is the vehicle for nutritional and gaseous exchange between the maternal and fetal circulations during pregnancy. The allantochorionic placenta of equids is classified as non–deciduate, non–invasive, epitheliochorial and diffuse and, as such, equine placentation demands fetomaternal interdigitation over the entire endometrial surface to optimise fetal development in utero. Any shortcomings are reflected by slower growth and delayed maturation of the fetus.

This requirement for an unabbreviated area of placental attachment is emphasised by the inability of mares to carry twin conceptuses to term due to simple competition between the two placentae for the limited area of endometrium which results in progressive starvation of one or both fetuses (Jeffcott and Whitwell, 1973). In addition, age–related chronic degenerative changes in the mare's endometrium (endometrosis) may compromise the uterine environment during pregnancy and Bracher et al. (1996) showed a close relationship between the health of the endometrium, the normality of structure and the density of the microcotyledons on the surface of the allantochorion, and fetal weight.

Since the 1980’s, two feed evaluation systems, the NRC and the INRA, have been proposed, suggesting allowances for energy and protein (Cuddeford, 1998). NRC recommendations include suggestions for digestible energy (DE) and digestible crude protein (DCP in 1978) and later crude protein (CP in 1989). INRA, (from 1984-1990), have firstly suggested the Net Energy System (NE), also referred to as the UFC system in French, (so called, as the NE system relies on expressing the NE value of a feed relative to a reference feed [barley], or Horse Feed Unit). The INRA have also gone on to recommend the Horse Digestible Crude Protein system (HDCP, or MADC in French). Whilst the INRA and NRC systems have both proposed nutritional requirements, the NRC is exclusive in its use of a protocol called the ‘factorial method’.The factorial method was initially contrived to allow for the determination of physiological expenditure, where the efficiencies of the nutrients were known and relevant. Other influences could then be considered by implementing feed trials to determine allowances which would take into account most environmental factors. Both the NRC and the INRA have proposed a range of Dry Matter Intake (DMI) values, which intend to meet the nutritional requirements of differing types of horses. DMI values provided by the INRA have been drawn directly from feeding experiments conducted over the last 30 years. Ingestibility of the main types of forages have also been extensively measured in horses, using feeding trials devoted to that purpose. The following chapter will review existing methods and suggest a progression strategy towards a common rationing system.

This paper describes how experimental adaptation of the mobile bag and in situ porous bag techniques for use in nutrition studies with equines, combined with mathematical modelling of feed degradation profiles and digesta passage rates, allows the quantitative partition of feed degradation amongst the major segments of the equine digestive tract. Dry matter effective degradability values in the small intestine (pre–caecal), caecal and colonic segments of the equine digestive tract for four fibre feeds are presented. Measurement of digesta passage rates in the caecum and total tract of equines are also discussed. Further studies are now required to capitalise on this development and partition degradation of individual feed constituents in common equine feeds across each of the major segments of the equine digestive tract. This would allow optimum, balanced and healthy diets to be formulated in practice across a wide range of equine husbandry systems.

Four in vivo apparent digestibility trials were carried out over a period of two years using 4 to 6 Welsh cross pony geldings of approximately 300kg LW. In all experiments ponies were individually housed in 10x12 ft loose–boxes with rubber mat flooring. In Experiment 1 three diets were offered ad libitum to 6 ponies in a replicate 3 x 3 Latin squares design. In Experiments 2, 3 & 4, four ponies were offered 1.5 – 1.75 % of LW per day in dry matter (DM) in 4 x 4 Latin square changeover designs. In all experiments periods lasted for 21 days, a 16-day adaptation period followed by a 5-day data collection phase. Diets were fed in two equal meals per day and water was available ad libitum. Dried feed and faecal samples were analysed for DM, ADF, NDF and CP using the methods of the AOAC (1990), GE was determined via bomb calorimetry and non–starch polysaccharides (NSP) were quantified by the method of Englyst and Cummings (1984). Differences between diets were determined by analysis of variance (Genstat 5, 2000). NSP analysis gave detailed information on the individual fibre constituents and allowed the subtle differences between feeds to be identified. The DMI of grass and red clover silages were 0.6 and 1.7 kg/d greater than hay indicating that the low DM content of these two forages does not negatively affect feed intake. The apparent digestibilities of these two feeds were also significantly greater than hay for all parameters measured. In Experiment 2 the combination diets of alfa-beet and hay (AB:H) and sugar beet and hay (SB:H) fed in 60:40 and 70:30 ratios were all significantly more digested at > 50% than the hay only diet at <39% for DM, CP, NDF, ADF, NSP, Ca, P and Mg. The addition of AB to H in the 70:30 diet produced a DE value of 2.89 MJ/kg DM higher than the hay alone only diet and also caused an associative affect which improved the digestibility of CP, arabinose, galactose and uronic acids from the hay portion of the diet. No significant differences were noted between the digestibilities of the proximate constituents for the chopped hay replacer (CHR), CHR and highly digestible fibre (HDF) cubes and CHR and course mix (CM) fed in Experiment 3. When looking at the digestibilities of the individual NSP constituents the CHR : CM diet was generally less digestible than the CHR: HDF diets indicating that HDF cubes are equally well or more digestible than a diet containing conventional course mix. With DE values similar to the CM the HDF feed can be offered as a valuable alternative to concentrates in equid diets. The high fibre forage (HiFi) fed in Experiment 4 was also highly digestible for all constituents measured and showed that a combination of chopped straw and alfalfa makes an excellent fibre feed for horses. The results from the four experiments reported here show that detailed chemical analysis is extremely valuable when choosing complimentary fibre feeds for horses. Moreover all the fibre feeds examined here were more digestible than hay. Feeds like the HDF cubes can be used to replace some or all of the cereal portion of the diet. The associative effects between the alfa-beet and hay and the mineral digestibility from these alternative feeds also suggests that not only is gut health enhanced, but that the supply of nutrients from these feeds makes them ideal choices for stabled horses.

Within the body there is continual production of entities known as Reactive Oxygen Species (ROS). These include radical derivatives of oxygen that contain at least one unpaired electron and include species such as the superoxide and hydroxyl radicals. ROS also include nonradical derivatives of oxygen that are capable of oxidising biomolecules such as hydrogen peroxide, ozone and nitrogen dioxide. ROS are formed from processes such as the respiratory burst of phagocytes and from mitochondrial oxidative phosphorylation, so production is often increased by situations that elevate oxygen utilisation such as exercise. ROS may also act as “signalling” species within the body. Controlled production of ROS is therefore essential for normal cellular function and health, especially with respect to the functioning of the immune system. However, uncontrolled production of ROS can result in cell damage and death, the induction and propagation of inflammation and DNA damage. Thus, the body has evolved intricate and elaborate enzymatic and non–enzymatic antioxidant defences to control and buffer excess ROS production. In situations where the antioxidant defences are overwhelmed either due to their depletion, malfunction or simply due to excessive ROS bombardment, oxidative stress and oxidative damage are likely to occur.

There are about 900,000 horses kept in the UK for leisure and a further 65,000 kept professionally (British Horse Society, 2003). Altogether about 800,000 ha are utilised for grazing and feeding horses, making the equine industry the second largest in the UK land based sector, after agriculture. The purpose of this paper is to review the present information on the management of grassland for horse grazing and for conserved forage, to identify some current issues and to postulate some areas for future research and development.

Maximizing the contribution made by grazing to the nutrition of the horse is a reasonable goal if economy is the main priority. Even if this is not the case, horses have a need to satisfy their natural instinct to graze. The deterioration of poorly managed grassland associated with equine enterprises is well documented (Odberg and Francis–Smith, 1976, and Judd et al., 2001). Horse grazing differs from grazing by cattle and sheep, in particular in the way that they select species and in the spatial pattern of their grazing.

Eventing is a very expensive sport to organise and run and relies heavily upon sponsorship funding to enable it to remain financially viable. This research is concerned with the challenges that events face in attracting and retaining sponsorship and what can be done to address these problems, resulting in a clearer understanding of what makes a successful sponsorship. Fourteen interviews were conducted with both event organisers and sponsoring companies, as well four people who are considered to be knowledgeable about sponsorship within the equine industry, to ensure that a balanced view of the issues was gained. The research found that the industry suffers from a culture of patronage with some companies sponsoring eventing for altruistic reasons. They see sponsorship as a way of raising public awareness and of building goodwill with their customers by being seen to put something back into a sport that their customers care about. Sponsors commented that sponsorship impresses people and gives them an idea about the values of the company and where it is positioned within the industry. They saw the sponsored event as an opportunity for them to entertain clients, customers, press and other business professionals, often in very beautiful surroundings. As eventing attracts more AB and C1 competitors and spectators than any other sport, it can offer sponsors an opportunity for highly targeted marketing to a sector of the population who are acknowledged to be difficult to reach via traditional advertising. Sponsors are interested in getting value for money from their sponsorship, and they expect to be dealt with in a professional manner. Event organisers need to demonstrate clearly how the sponsorship will benefit the company and ensure that they meet all of the sponsors’ business objectives. Sponsors expect to have name and brand awareness delivered to their target audience at the event, thus organisers must ensure that this happens by providing good branding opportunities. In order to gain the maximum benefit from the sponsorship, the sponsoring company needs to promote and publicise the sponsorship as much as possible by integrating it across their whole marketing strategy. This can be a great advantage to the event organiser as it raises the profile of the event. Events at the top end of the sport were found to have good sponsorship deals in place and the organisers said that they did not need sponsorship to make their events viable. However, the smaller events at grassroots level are only viable if sufficient sponsorship can be found. One interviewee suggested that these small events need to target smaller local companies who could benefit from raising their public profile in the local area. The event organisers interviewed feel undervalued by British Eventing, the sport’s governing body, and think that British Eventing could do more to support event organisers in attracting and retaining sponsorship. This is particularly crucial at grassroots level, because without sponsorship these events are not financially viable.

Thoroughbred mares (Equus caballus) are usually first teased 6 days post foaling and during this brief (often 3-6 minutes) process the mare's foal will be left alone in its stable. This will be repeated daily until the mare goes out of season. During this part of her cycle she may later be sent for covering by the resident stallion. On some farms the foal is alone in its stable during covering and this period can last for anything from 20 minutes to an hour, during which the foal typically exhibits signs of considerable distress. Though the foal can be heard whinnying for the mare, it has not previously been noted what behaviours the distressed foal exhibits during this separation. Though a recent study by Houpt (2002) looked at responses of 10 pony mares and their foals to brief weekly periods of separation at up to nine weeks of age, most research on separation distress in foals has previously been done with respect to the artificial weaning process, an event that most Thoroughbred foals experience by 6-7 months of age.

Locomotor stereotypies such as weaving and nodding are commonly observed as pre–feeding activity in stabled horses (Cooper, McDonald and Mills, 2001), whilst oral activities such as crib–biting and woodchewing may be associated with the post–feeding period (McGreevy and Nicol, 1998) particularly in horses fed a low–fibre concentrate (Nicol et al., 2002). In this study, we investigated the effect of increasing the number of meals of concentrate whilst maintaining the same daily concentrate intake, on the behaviour of stabled horses with particular reference to stereotypic activities such as weaving and crib–biting. The study was carried out on a working equestrian yard with stables for up to 50 horses.

A pilot study was used to record incidence of stereotypic behaviour and to select subjects for the main study. In this, the behaviour of 30 warm–blooded horses was recorded during their morning (0830h) and afternoon (1630h) concentrate meals. Each meal consisted of 0.5kg of a commercial feed, mixed with 1kg of soaked sugar beet pulp and 0.5kg of chopped hay and straw mixed in a bucket.

The moisture content of keratinous materials such as hoof horn is important as the presence of moisture has an inverse relationship on the mechanical properties of hoof horn and may have a subsequent effect on the function of the hoof. Methods previously used to dehydrate samples to calculate the moisture content of hoof horn vary considerably (Hopegood, 2002). Subsequent comparison of results is therefore unreliable. A comparison of different methods of dehydrating hoof horn was therefore carried out to establish a standardised protocol for dehydrating hoof horn to assess its moisture content. The moisture content of donkey hoof horn from normal animals and those with laminitis has not been reported. Maclean (1971) established that the moisture content of cattle suffering from laminitis was significantly higher than normal hooves. The resultant standardised protocol from the first part of this study was then used to compare the moisture content of hoof horn samples taken from horses, donkeys and those donkeys that had suffered from laminitis.