Rising calves for running belts

High-frequency kinematographic studies of the footing process of cattle on the treadmill


1 From the Department of Livestock of the Vetsuisse Faculty University of Zurich (Director: Prof. Dr. Dr. hc U. Braun) High-frequency kinematographic investigations of the felling process of cattle on the treadmill INAUGURAL-DISSERTATION presented by the Vetsuisse Faculty University of Zurich to obtain a doctorate Sven Werner Meyer veterinarian from Waldshut-Tiengen, Germany approved at the request of PD Dr. K. Nuss, Speaker PD Dr. Ch. Lischer, co-referee Zurich, 2006 Central Office of the Student Union

2 my parents 2

3 1 SUMMARY 5 2 SUMMARY 7 3 RESUME 9 4 INTRODUCTION 11 5 LITERATURE OVERVIEW Statics and dynamics of the musculoskeletal system Movement Movement without change of location Movement with change of location Footing Reasons for movement analysis Movement analysis in horses Use of the treadmill for diagnostics in horses Getting horses used to the treadmill Movement and foot analysis in cattle Load measurements on the claws in cattle Differences in claw size and load between fore and hind limbs Differences between medial and lateral claws Pressure distribution within the claws Influence of hoof care on the load conditions Dynamic pressure measurements 30 3

4 6 ANIMALS AND METHODS Animals Procedure of the examinations Hygiene on the treadmill Digital high-frequency camera with PC and software Lighting Film recordings Claw care Treadmill and force measurement Evaluation of the data Animal experiment permit 43 7 RESULTS High-frequency cinematography First contacting claw Contact region of the claws touching the ground Delayed placement of the medial claw measurements on the treadmill Speed of the treadmill Step frequency Support leg phase Sloping leg phase Vertical impulse Percentage load on fore and hind limbs 56 8 DISCUSSION 57 9 LITERATURE LIST OF ACKNOWLEDGMENTS 69 4

5 1 SUMMARY The aim of this dissertation was to document the footing process of healthy young cattle on the treadmill using high-frequency kinematography and to determine the influence of functional hoof care on it. 18 female, on average (± 2.61) months old and (± 65.10) kg heavy young cattle of the Brown Swiss breed were examined. After a set training period, all cattle were filmed on the treadmill at an average walking speed of 1.36 (± 0.06) m / s. Digital film recordings were made with a frequency of 500 frames / s. Force measurements were also carried out on nine animals to determine the load on the limbs, as well as measurements of the slope and support leg phases and the vertical impulse. After the functional hoof care had been carried out, the film recordings and the measurements were repeated. The support leg phase lasted 0.70 (± 0.03) seconds on the forelimbs and an average of 0.69 (± 0.03) seconds on the hind limbs. The hanging leg phase lasted 0.39 (± 0.02 s) on the forelimbs and 0.40 (± 0.02) seconds on the hind limbs. The maximum vertical impulse was Ns (±) on the forelimbs and Ns (±) on the hind limbs. The shoulder limbs were significantly more loaded with% than the pelvic limbs with%. Before the functional claw care, the outer claw on the pelvic limbs touched the ground 100% first, then%. On the shoulder limbs, the outer claw also came first,% before and% after claw trimming. The medial claw touched the hind limbs (± 0.009) (± 0.006) seconds and the forelimbs (± 0.008) (± 0.011) seconds later. Animals that did not make the first contact with the outer claw footed on the outer and inner claw at the same time. The region of the first contact of the outer claws before claw care was in equal parts with the ball of the foot and 5

6 support edge. After hoof trimming, the ball of the foot dominated. The medial claws showed a few clearly predominant types of footing. On the medial claws of the hind limbs, after claw care, the stretcher edge footing prevailed; on the fore limbs, there was an almost equal distribution between the ball of the foot and the foot of the stretcher. It was thus possible to establish that the young cattle regularly fisted on both the shoulder and pelvic limbs with the outer claws first. The functional hoof trimming did not influence this process. In healthy claws, the lateral claw takes the first weight load with the foot and at the beginning of the supporting leg phase, namely with the ball of the foot, while the medial one takes up later and predominantly with the support edge. This increased stress on the ball of the outer claws could contribute to the development of claw damage, especially in cows that are kept on hard floors. 6th

7 2 SUMMARY The goal of this study was to evaluate the pattern of the ground contact of the claws of clinically healthy heifers on a treadmill using high-speed cinematography, before and after claw trimming. Eighteen female cattle, which were a mean of (± 2.61) months old and weighed a mean of (± 65.10) kg, were used. The animals were Brown Swiss heifers, which had been kept on alpine pastures or in loose housing systems. All the animals had healthy claws and the lateral claws of the hind limbs were slightly larger than the medial claws. In all the heifers, high-speed cinematography was carried out after a training period on the treadmill, on which the heifers walked at a mean speed of 1.36 (± 0.06) m / sec. Digital recording at a frequency of 500 photos / sec was carried out before and after functional trimming. In nine heifers, vertical force measurements were also taken to assess weight bearing by the claws, and the duration of the swing and supporting phases of the limbs were determined. This was repeated after functional hoof trimming. The mean duration of the supporting phase was 0.70 (± 0.03) seconds in the forelimbs and 0.69 (± 0.025) seconds in the hind limbs. The swing phase lasted a mean of 0.39 (± 0.018) seconds in the forelimbs and 0.40 (± 0.02) seconds in the hind limbs. The mean vertical force the left and right forelimbs was Ns (±) and Ns (± 109.50) for the left and right hind limbs. Based on these measurements the forelimbs bore 55.10% of the total vertical force. There were no significant differences in the supporting and swing phases and vertical force in claws before and after functional hoof trimming. Before functional hoof trimming, the lateral claws of the hind limb contacted the ground first in 100% of the feet compared with 97.20% after claw trimming. In the forelimb, the lateral claw contacted the ground first in 83.00% of the feet before functional hoof trimming and in 91.60% of the feet after hoof trimming. The medial claw in the front limb contacted the ground (± 0.008) (± 0.011) seconds later than the lateral claw and (± 0.009) (± 0.006) in the hind limb. In all cases in which 7

8 the lateral claw did not contact the ground first, the two claws contacted the ground at the same time. In the hind limb, the region of the lateral claw that first contacted the ground was the bulb in 50.0%, the abaxial wall in% and the toe in 5.60% of the claws. After functional hoof trimming, the bulb contacted the ground first in% of the claws. In the forelimb, the first contact of the lateral claw with the ground was by the abaxial wall in% of the claws, by the bulb in% and by the toe in%. As in the hind limbs, the percentage of lateral claws in which the bulb contacted the ground first increased and was% after functional trimming. In the medial claws of the hind limbs, the abaxial wall contacted the ground first in 63.0% of heifers, followed by the bulb in%. After functional trimming, the abaxial wall contacted the ground first in% of the heifers and the bulb in 19.4%. In the medial claws of the forelimbs, the abaxial wall, the bulb and the toe contacted the ground first in%,% and% of the heifers, respectively. After functional claw trimming, the bulb contacted the ground first in% of the heifers, the abaxial wall in% and the toe in 2.70%. Thus, in these young heifers, the lateral claw consistently contacted the ground before the medial claw in both the fore and hind limbs. Functional trimming did not significantly influence this pattern. Therefore, in the normal situation the lateral claw absorbs most of the vertical force during initial contact with the ground and the early supporting phase. The main effects of functional claw trimming were that the region of first contact with the ground shifted predominantly to the bulbs in the lateral claws and to the abaxial wall in the medial claws. It can be concluded that in normal claws, the bulb of the lateral claws of both front and hind limbs receives most of the initial vertical impact. This may contribute to the development of claw diseases, especially in animals housed on hard surfaces. 8th

9 3 RESUME Le but de cette étude était d évaluer par le principe de haute vitesse cinématographique, le mode de contact des onglons de génis cliniquement en bonne santé sur un tapis roulant et de juger l importance du parage des onglons. Pour ce faire, dix-huit génis du type Brown Swiss d un age moyen de (± 2.61) mois et ayant un poids moyen de (± 65.10) kg ont été utilisées. Pour chaque géisse, après un entraînement de marche sur le tapis roulant, un film d une fréquence de 500 photos / sec a été pris à une vitesse moyenne de marche de 1.3m / sec. La mesure des forces verticales a pu être effectuée pour neuf génis, ainsi que des mesures concernant la durée d appui des onglons et les phases de support et de repos des pattes. Ceci a été répété après le parage des onglons. The duration of the support phase était de 0.70 (± 0.03) secondes pour les pattes antérieures et de 0.69 (± 0.03) secondes pour les pattes postérieures. The phase de repos durait en moyenne 0.39 (± 0.02) secondes pour les pattes antérieures et 0.40 (± 0.02) secondes pour les pattes postérieures. Il n y avait pas de différence significative entre les phases de support et de repos ainsi que les forces verticales dans les onglons avant et après leur parage. La moyenne des forces verticales des pattes antérieures était de Ns (±) et de Ns (±) pour les pattes postérieures. The forces se répartissaient à% sur les membres antérieurs contre% sur les membres postérieurs. Avant le parage, les onglons latéraux des pattes postérieures avaient un premier contact de 100% avec le sol et après parage, ce contact se réduisait à%. Pour les pattes antérieures, avant le parage l onglon latéral avait un premier contact de% avec le sol et après parage, ce contact s élevait à%. L onglon médial des pattes postérieures touchait le sol en (± 0.009) (± 0.006) après l onglon latéral. L onglon médial des pattes antérieures avait contact avec le sol en (± 0.008) (± 0.011) secondes plus tard que l onglon latéral. In tous les cas où l onglon latéral n était 9

10 pas le premier à toucher le sol, les onglons latéraux et médiaux ont atteint le sol au même moment. Avant le parage, les zones de l onglon latéral qui touchaient en premier le sol étaient à part égale le bulbe et la paroi external. Après le parage des onglons, c est le bulbe qui touchait d abord le sol dans la grande majorité des cas. Pour les onglons du côté médial, il ny avait pas de type privilégié de premier contact au sol.Aprés le parage, le premier contact de l onglon du côté médial des pattes postérieures se faisait en majorité sur la paroi external alors que pour les pattes antérieures , ces contacts se répartissaient à part égale sur le bulbe et la paroi external. Ainsi a pu être montré que chez ces jeunes génis, l onglon latéral touchait le sol avant l onglon médial, pour les pattes antérieures also bien que postérieures. Le parage des onglons n a pas eu d influence significative sur ce phénomène. Ainsi, en situation normal, l onglon latéral absorbe une grande partie les forces verticales lors du contact avec le sol au début de la phase d appui et ceci avec le bulbe, alors que l onglon médial a un contact retardé qui a lieu surtout sur la paroi external. Ceci pourrait contribuer au développement des maladies des ces onglons, en particulier chez les animaux vivant sur un sol à surface dure. 10

11 4 INTRODUCTION The diagnosis of lameness in animals is based on observing the movement of the diseased limbs. As a result of the rapid movements, however, subtle changes in the gait pattern are difficult to recognize. Therefore, modern techniques are used to examine the gait pattern. Kinematic methods use videography, acceleration measurement and high-frequency kinematography to quantify movements. Kinetic studies are based on the recording of pressure, extension and friction forces with modified horseshoes, force plates or pressure-sensitive mats (SEEHERMAN, 1992a; b). Kinetic measurements have so far been able to determine unequal ground reaction forces, particularly on the claws of the pelvic limbs of cows (Van der Tol et. Al. 2003). Although lameness and especially the importance of hoof diseases in cows have been well documented (NUSS and STEINER, 2004), little is known about the footing process in healthy cattle. Therefore, the aim of the present work was to document the footing process of young cattle on the treadmill with the help of digital high-frequency cinematography, to describe it in detail and to check the influence of functional hoof care on the footing process. 11

12 5 LITERATURE OVERVIEW 5.1 Statics and dynamics of the musculoskeletal system The mammalian organism, like every movable body, is influenced by the laws of statics and dynamics. The statics deals with the construction principles for maintaining the balance of individual body parts or the entire animal body, both when standing and when moving. Dynamics deals with the interaction of the active and passive musculoskeletal system in locomotion (SEIFERLE and FREWEIN, 1984). As a solid body, the animal organism is also subject to the static laws, but its structural elements not only have to carry the body load and keep it in balance, but also serve to facilitate movement. They are therefore mostly loaded both statically and dynamically. The dynamic load varies depending on the intensity of the muscle contractions and the speed of the movement. In general, it can be said that the large herbivores, due to a certain stiffening in the trunk area, are less agile and flexible than the carnivores (SEIFERLE and FREWEIN, 1984). The position of the center of gravity or center of mass of the entire body, which is dependent on the posture (KOLB, 1989), is of great importance from a static point of view. The center of gravity is an imaginary point within or outside of a coherent mass, to which the sum of all torques acting on the mass from the earth's gravitational field = 0 (GIESE, 1997). While this is in the horse at the intersection of the median plane with a transverse plane immediately behind the proc. xiphoideus and a horizontal plane between the lower and middle third of the trunk, it is a little further caudal in ruminants (SEIFERLE and FREWEIN, 1984; KOLB, 1989). The additional load on the shoulder limbs can be seen from the position of the center of gravity. So at 12

13 Cattle the greater part of the body load% (KOLB, 1989), 54%, (ALSLEBEN et al. 2003), 52.4% -54.8% (HUTH et al. 2004, 2005), 52% -58% ( ARKINS, 1980), 51% (VAN DER TOL et al. 2002, 2003) - carried by the shoulder limbs than the pelvic limbs. Fig. 1: Position of the center of gravity of domestic mammals on a rectangular support surface (KOLB, 1989). In principle, the position of the center of gravity is not constant, but is significantly influenced by the posture of the head, the filling status of the abdominal viscera and, in cows, by the shape of the udder, the current stage of lactation and the stage of pregnancy (FESSL, 1968). It should also be taken into account that sex dimorphism is more pronounced in cattle than, for example, in horses (FESSL, 1968). The rectangular area defined by the tips of the extremities of the feet is called the support area. It is relatively large in domestic mammals compared to that in humans (Fig. 1). The animal body remains in equilibrium as long as the gravity corer hits the support surface. It can also be seen from the load and the construction of the limbs that the shoulder limb assumes the character of a vertical support column and a safety lever mechanism for the load pushed from behind. The pelvic limbs, on the other hand, form a more angled lever or throwing lever mechanism that provides the main thrust for forward movement. The steep position of the limbs also distinguishes the cattle as a flight animal (JENKINS, 1971). 13th

14 5.2 Movement Movement without change of location Movements without change of location in cattle include lying down, standing up, standing up on the hindquarters and lashing out Movement with change of location Locomotion is part of the behavioral repertoire of cattle, i. H. Cattle have an innate urge to move, which can also be seen as an expression of physical and psychological well-being (GIRTLER, 1988). Restricting movement affects the animals' wellbeing (BRADE, 2002) and also leads to reduced blood flow to the claw dermis (LISCHER et al., 1998). The restriction of heat behavior is also described (PHILLIPS and MORRIS, 2000). Cows walk distances between two and 12, on average around three to four kilometers per day (BRADE, 2002). As a rule, they move slowly and quietly. Cows suffer from stress when they constantly have to walk faster than 5 km / h.Especially lactating and pregnant cows (ALBRIGHT and ARAVE, 1997), which are particularly prone to hoof problems, should not be driven too quickly (LISCHER et al., 1998). The forward movement of the cattle in the step can be divided into four movement phases of different duration, which are lined up in a constant sequence: at the moment of lifting and rolling over the toe wall (Fig. 2a), a limb detaches from the ground and goes into the phase of swinging (Fig. 2b and 2c), during which she is guided forward by bending her joints, but then stretching her joints. After the limb has gained a foothold again, it goes over to supporting (Fig. 2d) the trunk, the weight of which initially pushes its joints through a little. The limb stretches again through vigorous muscle contractions and leads phase 14

15 of the caulking (Fig. 2e). During this phase, the trunk is pushed forward so far that the footing surface separates from the floor and a new lifting begins (ALBRIGHT and ARAVE, 1997; PHILLIPS and MORRIS, 2000; ALSLEBEN et al., 2003). During lifting and swinging, the limb is in the so-called hang leg phase. a b c d e Fig. 2a-d: Movement cycle of the left front leg of the cattle: a) lifting, b) swinging, c) stretching and feet, d) props, e) lifting. (NICKEL et al., 2001), difi i 15

16 The solid lines connect the support points Fig. 3: Sequence of limb loading in the step (KOLB, 1989). The sequence of movements that a limb goes through from the lifting of the foot surface to the next lifting is called a step, and the distance that is covered is called the step length. The step is the slowest type of forward movement and represents a four-stroke movement. Depending on the sequence of the footing limbs, the result is a sagittal or diagonal bipod support. However, the animals often move more slowly and lengthen the support phase compared to the slope leg phase. In this way, you add a tripod support between the sagittal and diagonal bipod support, which distributes the load better. Tripod supports are twice as common in cows with sole ulcers as in healthy ones (FLOWER et al., 2005). Although the cattle's stride does not usually differ from that of the horse, the special case can arise that when swinging a rear extremity that of the front extremity on the same side sets in more quickly, whereby a criterion for the stride is that the pelvic limb of the corresponding shoulder limb 16

17 is half a stride ahead, is no longer fully met. In such a case the cow goes in a half pass. The half pass represents the fit of the step and is also referred to as an impure or slow pass (KOLB, 1989). The rhythm of the limb movement is also expressed to a certain extent in certain movements of the trunk. The head, neck and sometimes also the tail follow the movements of the four limbs in rhythm. The head and neck are raised in the swing phase and lowered in the support phase. On the pelvic limbs, the active side rises in the swing phase and lowers in the support phase. The tail always swings to the side of the supporting shoulder limb (KOLB, 1989). Leading cows by the hand can lead to an uncharacteristic sequence of movements (SCOTT, 1988). 5.3 Footing Under footing or treading in cattle, one understands the placing of the claws on the ground. With all ankle and toe joints stretched, the limb is slanted forward and downward and the claws are placed on the floor (PHILLIPS and MORRIS, 2000). The footing area of ​​the claws depends on their condition, the position of the limbs and the movement of the limbs. The friction that occurs is referred to as foot friction and is responsible for the wear and tear of the claw horn in the wearing area (RUTHE et al., 1997). Especially when cattle are kept in loose stalls, the degree of horn abrasion is determined by the nature of the floor area. Moisture (water, feces and urine) acts as a lubricant and lowers the friction forces (PHILLIPS and MORRIS, 2000). At the same time, basic friction (coefficient of friction 0.4) in the floor is a prerequisite for the cow to walk safely (VAN DER TOL, 2004). 17th

18 5.4 Reasons for the movement analysis The main difficulty in analyzing the movement sequence is that the movement phases of the four limbs are more or less shifted from one another in time, i.e. each limb assumes a different position in a certain gait at a defined moment (SEIFERLE and FREWEIN, 1984 ) and thus only the moment photography, the slow motion film or the high frequency cinematography provide insight into the interaction (KNEZEVIC et al., 1987). In addition, the methods mentioned allow an objectification of the assessment of a diagnostic anesthesia or the success of a therapy. They also serve to objectify the effect of orthopedic corrections or fittings. The results of modern locomotion analysis are also used to create and evaluate horse-friendly racecourse designs (FREDRICSON, 1975; FREDRICSON et al., 1975). In cattle, the video documentation is used in the context of lameness monitoring in loose stalls (COOK et al., 2004). 5.5 Movement Analysis in Horses An overview of the history of locomotion analysis is given by the works of WALTER (1925), KNEZEVIC (1985, 1987) and GIRTLER (1988): Aristoteles (before Chr.) Made general observations about the limb movements and their coordination in four-legged friends. Newcastle (1657) used the hoofbeat sound as a criterion for the investigation of movement. Giovanni Alfonso Borelli () studied muscle mechanics in detail. He carried out motion analyzes in various mammals and was the first to determine the body's center of gravity. Goiffon and Vincent (1779) recognized connections between speed and gait. They attached bells to each hoof so that they could better define each gait. 18th

19 In these early works it was recognized that successive sequences of movements are similar and that locomotion is a cyclical process. Etienne Jules Marey in Paris and Edward Muybridge in San Francisco worked on horse locomotion in the late 19th century (KNEZEVIC, 1985; KNEZEVIC et al., 1987). Marey (1874) initially used various devices for registering the movements of horses: firstly, a pneumatic, automatic recorder in the form of a rubber ball filled with horsehair, which was fastened under all four hooves. A rubber sleeve was used as the second measuring device, which was attached directly above the fetlock joint and recorded the pressure fluctuations caused by the movements. Third, he used two drums with levers attached to the horse's croup and withers to record vertical movements (KNEZEVIC 1985, 1987). Later (1882) he used long strips of paper and celluloid, which were moved past a lens by turning a crank and exposed. He called this process "chronophotography" and thus invented the cinematographic recording process (WALTER, 1925). He called geometrical chronophotography "another recording technique in which the individual limb sections of a person dressed in black who was also moving in front of a black background, marked by sewn-on shiny strips and dots and recorded while moving. Edward Muybridge created photo series of horses in different gaits with a battery of 12 or 24 cameras, which were switched in sequence (MUYBRIDGE, 1898). In 1888, the world's first photo-finish at a horse race took place in New Jersey using this technique. WALTER (1925) studied the movements of horses using the chronophotography described by Marey. He projected the images on paper at a magnification of 20 times, drew mechanical axes and reconstructed joint angles. KNEZEVIC et. al. (1985 and 1987) carried out studies on horses that were marked with reflective foils or light-emitting diodes on defined areas of the body. 19th

20 The movement was recorded over a length of 10 meters by a fixed, swiveled high-frequency film camera (200 images / sec) or an infrared camera. This resulted in an abundance of quasi-uniform movement phenomena of different localization. DREVEMO et. al. (1980) carried out studies on trotters using high-frequency kinematography. Three systems in particular dominated the kinetics. Force measuring plates, force measuring shoes and measuring lines. The results differed qualitatively and in some cases involved considerable technical effort (DOHNE et al., 1990). A treadmill with an integrated measuring system was also used (WEISHAUPT et al., 2002). 5.6 Use of the treadmill for diagnosing horses The treadmill has gained great importance as an instrument for standardized performance physiological and sports medical examinations in equestrian sports over the past decades. Since the first studies in Sweden (PERSSON, 1967), the treadmill has also had a firm place in the analysis of movements in horses (FREDRICSON et al., 1983; BUCHNER et al., 1995; WEISHAUPT et al., 2002). The treadmill has the advantage that the test person remains stationary and the examiner can study their movement from all sides (BUCHNER et al., 1995). This enables film documentations that can be evaluated and saved in slow motion. 20th

21 5.7 Getting horses used to the treadmill LEACH and DREVEMO (1991) pointed out the need to know about the differences in movement in animals on the treadmill compared to natural ground. The stride length on the treadmill was initially often shortened and thus the stride frequency was increased (SEEHERMAN, 1992). The horses were therefore systematically accustomed to the treadmill and also examined (SEEHERMAN, 1992). The working group around BUCHNER (1995) carried out kinematic studies in warm-blooded horses on the time it took to get used to the treadmill and on the differences to movement on firm ground. Before training on the treadmill, kinematic data was recorded on hard ground with different surfaces and then all horses were given a one-week controlled treadmill training session. After 2 to 3 training units of minutes each, the horses exhibited a movement pattern both at walk and trot on the treadmill that corresponded to that on concrete floor (BUCHNER et al. 1995). These studies by Seeherman (1992) and Buchner et al. (1995) laid the basis for the familiarization and examination of horses with the treadmill that is used today (WEISHAUPT 2005). 21

22 5.8 Movement and foot analysis in cattle Investigations into the position of the limbs and joint angulation in cattle were carried out by FESSL (1968). The animals were assessed while moving, from the side with the aid of a camera (48 images / s). Maximum extensions, flexions and the radius of action of the individual joints were also measured. The author also carried out investigations into the change in shape of the space between the claws in locomotion. He described active and passive movement processes in interdigital mechanics. Active movements occurred in the hanging leg phase and had their maximum (expansion of the interdigital gap) at the moment when the floating limb passed the supporting one. With further forward swing up to the foot, the space narrowed again (FESSL, 1974). The passive expansion of the interdigital space began with the foot and was dependent on the weight of the animal, the shape of the claws and the state of correction of the claws, as well as the nature of the ground (FESSL, 1974). With unfavorable claw shapes and smooth ground conditions, the passive interdigital movements were more pronounced than the active ones. Spreading or rotation of one of the claws while the partner claw was fixed on the ground could also be observed (FESSL, 1974). Further investigations by PHILIPS and MORRIS in 2000 and 2001 with the help of video recordings showed that cows reacted to the pen with changes in their locomotion behavior. They showed a steeper limb position, a flatter contact of the claws of the forelegs and a reduced step frequency with an extended support leg phase (PHILLIPS and MORRIS, 2000, 2001). The limb guidance was less rotational in the shoulder extremities, as they did not have to walk around the udder. This walking around as well as the external rotation of the outer claw led to a predisposition of the pelvic limbs to slipping in low-friction soil (moisture) (PHILLIPS and MORRIS, 2000). 22nd

23 High-frequency cinematography in cattle was first used by HERLIN and DREVEMO (1997). The authors carried out movement analyzes on Swedish Friesian cows in order to investigate the influence of two housing systems on the musculoskeletal system. In order to make the film recordings, the animals were walked at an average speed of 1.4 m / s on a flat, 20 m long concrete stretch. The recordings were made with a swiveling camera (100 images / s), which was positioned perpendicular to the direction of movement of the animals at a distance of 35 meters. The movement was analyzed by assessing the angle of the joints of the shoulder and pelvic limbs (Fig. 4) Fig. 4: Assessed limb points and joint angles in cows with two housing systems. (HERLIN and DREVEMO, 1997) They also determined the average stride duration (1,218 ± seconds) and the duration of the support leg and slope leg phase. There was a negative correlation between walking speed and duration as well as between the support and the slope leg phase. Step duration and support leg phase were positively correlated. 23

24 5.9 Load measurements on the claws of cattle Force plates make it possible to precisely localize any pressure peaks that occur and to divide the footing area into defined zones (MAIR et al., 1988; MAIR et al., 1988; DISTL et al., 1990; GREENOUGH and WEAVER , 1997). Force plates were first used in cattle in the 1970s (PRENTICE and WRIGHT, 1971) and have since been further developed by various investigators (OSSENT et al., 1987; MAIR et al., 1988; MAIR et al., 1988; DISTL et al. , 1990; HUBERT and DISTL, 1994; ALSLEBEN, 2002; ALSLEBEN et al., 2003; VAN DER TOL et al., 2003; HUTH et al., 2004; VAN DER TOL et al., 2004; HUTH et al., 2005). 24

25 5.9.1 Differences in claw size and load between fore and hind limbs Investigations into claw shapes and the distribution of body weight were carried out by FESSL (1968) on various breeds of cattle. After standardized hoof care with a sole thickness of six to eight millimeters, he found four predominant hoof types (Fig. 5). Type I Type II Type III Type IV For female Cattle mostly in front and behind, in bulls only in the back. Cattle mostly in the front, rarely in the back, in bulls mostly in the back. Cattle rear Mostly in front of young and old bulls Fig. 5: Claw shapes and their assignment to sex and age of cattle (FESSL, 1968) FESSL (1968) was able to show that the claws of the front extremities were always larger than those of the rear extremities. The difference was smallest in heifers and no differences in the shape of the claws could be found between the breeds. The claws of the shoulder limbs of young animals, of bulls (57% in young animals, 58% in old animals) and of cows up to the 25th week of pregnancy were more heavily loaded than those of the pelvic limbs. In cows between the 26th and 30th week of gestation, the front and rear load was 25

26 of the same size and later shifted by an average of two percent of the body weight in favor of the pelvic limbs (FESSL, 1968). Even with the von ALSLEBEN et. al (2003) carried out a study on young animals showed that in the first two years of life the proportion of the highest pressures was higher on the forelegs than on the hind limbs. In their investigations, they also measured a percentage load on the forelegs of 54% and on the hind limbs of 46%. The foot area of ​​the front limbs was always larger than that of the hind limbs. HUTH et. al. (2004, 2005) carried out studies on the distribution of pressure under the claws of calves of various breeds of cattle. Claw trimming was not carried out, the limb position was not described in detail. The fore limbs (305 N 376 N) were significantly more stressed than the hind limbs (276 N 310 N) and 52.4% to 54.8% of the body weight was carried by the fore limbs. The authors found that the high predisposition of the external claws of the hind limbs to diseases did not exist from birth, but only appeared to develop in the later life of the cattle (HUTH et al., 2004). In one by HUTH et al. (2005) carried out follow-up work with the same research objectives on the above-mentioned animals aged months, the forelegs (813 N to 993 N) were again exposed to higher loads than the hind limbs (692 N 783 N). With values ​​of 54.0% to 56.1% in these animals, too, the body weight was mainly carried by the forelegs (HUTH et al., 2005). 26

27 5.9.2 Differences between medial and lateral claws TOUSSAINT RAVEN examined the distribution of the weight load between the medial and lateral claws in 1971 using a split scale. Taking into account the hinge-like rear limbs attached to the pelvis and the stiff-elastic claws attached to it, he determined that it was always the outer claw on the hind limbs that was exposed to the less favorable (strongly fluctuating) loads. Even small deviations (outward movements) when stationary caused the loads on the outer claws to increase significantly.Because of the forelimb attached to the shoulder girdle with tendons and muscles, the statements that apply to the hind limbs could not be transferred (TOUSSAINT RAVEN, 1971, 1985, 1998). FESSL (1968) found that the outer claws on both the shoulder and pelvic limbs were larger than the medial ones with increasing body mass, with the difference being smaller on the front extremities (FESSL, 1968). SCOTT et al. (1988) were able to show that in the first three months of life, the main load with 62-63% of the body weight was carried by the forelegs. When determining the contact area, they measured the larger area on the forelegs on the lateral claws in the third and fourth months of life. From the fourth month of life, the forelegs had the greater share of the total foot area. On the hind limbs, the contact area of ​​the outer claws was between 25 and 50% larger than that of the inner claws. DISTL et al. (1990) carried out pressure measurements on the right forelegs of standing cows whose claws had been groomed 3 weeks earlier. The division of the claws into four sectors made it possible to compare weight and area in the subsections of the footing area (DISTL et al., 1990). The authors were able to show that the medial claw of the forelimbs was always more heavily loaded on the forelegs of the first lactation than the lateral hoof, whereas in the second lactation there was a relatively higher load on the lateral hoof. The pressure peaks 27

However, 28 occurred predominantly on the lateral hoof in both groups (DISTL et al., 1990). A disadvantage of the system used was the long interrogation intervals of the sensors, which made dynamic measurements impossible (DISTL et al., 1990). In contrast to the information provided by Scott (1988), ALSLEBEN et al. (2003) found that the medial claws were exposed to the higher pressures on both the fore and hind limbs. On the hind limbs, the load shifted to the outer claws from the 24th month of life. With regard to the relative weight on the foot area, the higher values ​​were measurable on both the fore and hind limb mass on the medial claws. With increasing age, however, there was an increase in the foot area of ​​the lateral claw (54% in the front and 55% in the rear). HUTH et al. (2004) found that in calves the medial claws were significantly more stressed on both the front limbs (62.5% to 68.7%) and the hind limbs (62.2% to 69.5%). In these calves, the medial claws of the forelimbs were larger and accounted for 54% - 58% of the total foot area. On the hind limbs, the proportion of medial claws was even more pronounced at 55% to 59%. Follow-up examinations on the now months old animals again showed an additional load on the medial claws of 58.1% to 65.9% on the forelimbs (HUTH et al. 2005). At this point in time, the authors were able to show that the lateral claws of the hind limbs occupied the larger foot area with 51.2% to 56.6% (HUTH et al., 2005). While the reversal of the area ratios took place in the 12th month of life (HUTH et al., 2005), the increase in mean pressures did not appear to occur until after the 18th month of life. The authors therefore pointed out the need to investigate the exact point in time of the reversal of the mean pressures from the medial to the lateral claw. KEHLER and GERWING (2004) determined foot areas on the hind limbs of standing cows with a ratio of 63% (outer claw) to 37% (inner claw). 28

29 5.9.3 Pressure distribution within the claws Consistent information is available in the literature with regard to the localization of the greatest loads. These load peaks occur in the caudal and axial sectors of the outer claws of the pelvic limbs (TOUSSAINT RAVEN, 1971; OSSENT et al., 1987; MAIR et al., 1988; MAIR et al., 1988; LISCHER et al., 1998; TOUSSAINT RAVEN, 1998; LISCHER, 2000; LISCHER and OSSENT, 2001; LISCHER et al., 2002; VAN DER TOL et al., 2002; ALSLEBEN et al., 2003; HUTH et al., 2004; KEHLER and GERWING, 2004; LOGUE et al., 2004; NUSS and STEINER, 2004; HUTH et al., 2005) Influence of hoof care on the load conditions KEHLER and GERWING (2004) examined what percentage of the pressure load the hooves had. They examined the pelvic limbs of standing cows from loose stalls before and after functional hoof trimming. They found that after performing the functional hoof trimming, the overload on the outer hooves was reduced from 68% to 52% and the load on the inner hoofs increased from 33% to 48%. This almost balanced relationship persisted for 6 weeks. The functional hoof trimming enabled a maximum increase in the total foot area of ​​12.9% over a period of 14 weeks, with the ratio of inner to outer hooves remaining almost unchanged. Already after 4 months, however, values ​​could already be measured in half of the animals as before claw care (KEHLER and GERWING, 2004). 29

30 5.9.5 Dynamic pressure measurements Using special claw irons, strain gauges and a multi-component force measuring plate, (SEEBACHER and FISCHERLEITNER, 1979) carried out investigations on cattle on concrete floors, gravel and on slatted floors. Using the data obtained, they determined the vertical load at orthopedically relevant points on the claw soles. The advantage of this combination of claw iron and strain gauge was the separate detection of both claws of an extremity in different soil conditions and with several successive movement cycles. SEEBACHER and FISCHERLEITNER (1979) found that when the foot was used, the tip of the claw and the axial support edge were mainly stressed, and maximum stresses of up to two thirds of the body weight occurred. When walking, the force distribution shifted significantly from the tip of the claw to the gap between the claws. Measurements of the ground reaction forces in moving cattle were carried out by WEBB and CLARK (1981) and SCOTT (1988). They used a multi-component force plate in combination with a pedobaroscope. According to the force-time curve drawn up by SCOTT (1988), only a maximum force occurred in the middle of the support leg phase in the forelegs, while a two-peak curve was recorded on the hind limbs (Fig. 6). A small initial rash could be seen at the upfill, which was rated as an impact disorder. This occurred before the actual main peak of the curve. 30th

31 Fig. 6: Course of the ground reaction forces 2273 of fore and hind limbs in cattle in the walk (SCOTT, 1988). Higher forces in the forelegs, two-lobed curves on the rear limbs. The ground reaction forces increased linearly with the body weight of the cattle. Regarding the load on the individual claws, SCOTT (1988) found that from the age of six months the lateral claws of the fore limbs were more heavily loaded than the lateral claws of the hind limbs (SCOTT, 1988). The ball of the foot and the abaxial wall of the lateral claws were most heavily loaded. The widening of the inter-claw gap during the support leg phase was interpreted as an increase in the contact area of ​​the claws, which led to the inclusion of the sole, with a subsequent reduction in focal pressure peaks (SCOTT, 1988). VAN DER TOL et al. (2003) determined the ground reaction forces in standing and walking cows. A combination of a force and pressure measuring plate (KISTLER plate and FOOTSCAN plate) was used for the examinations on walking animals, which made simultaneous measurements possible. The query intervals were 250 Hz. Due to the small size of the measuring device, however, about 40 runs per animal were necessary for exact results (VAN DER TOL et al., 2003). On the forelimbs, 31

32 the authors measured a footing over the ball of the outer claw, followed by a less pronounced ball of the inner claw. There were maximum values ​​of N for the outer claw and N for the inner claw. In the further course of the support leg phase, the main load shifted towards the inner claw. When walking, the maximum loads (649.4 N) were in the apical part of the inner claw. On the hind limbs (total load: N), the main load (N) was on the outer claw. The fore limbs (N) were significantly more stressed than the hind limbs (N). The foot area was also significantly larger on the forelimbs (54 cm 2) than on the hind limbs (47 cm 2) (VAN DER TOL et al., 2003). The average pressure loads on the front limbs were given as 50 N / cm 2 and on the rear limbs as 60 N / cm 2, and even increased to values ​​of N / cm 2 at the time of the footing. The maximum pressure loads on the front limbs were 105 N / cm 2, on the rear limbs 130 N / cm 2. At the time of the footing, the loads increased further to values ​​of N / cm 2. 32

33 6 ANIMALS AND METHODS The aim of the present work was to document the footing process of healthy young cattle on the treadmill using high-frequency cinematography and to determine the influence of functional hoof care on footing. The films of the digital high-frequency camera should be evaluated with regard to the following questions: 1.) Do both claws hit the ground at the same time or separately during the footing process? 2.) With which region of the claw (s) is the first contact made? 3.) Are there measurable delays between the setting of the inner and outer claws? 4.) What influence does the functional hoof care have on the footing process and / or the claw region with which the first contact is made? The questions related to both the fore and hind limbs. A distinction was made between the footing of the outer and inner claws, namely in the areas of the ball of the foot, the support edge - or parallel and the tip of the claw. Parallel footing was the planar placement of the claws on the treadmill, as it became visible when viewed from the side. In the case of footing over the tip of the claw, it was a question of the initial contact of the tip of the claw and not of the tip of the toe, which is a typical finding in lameness. In half of the cattle (9/18), the ground reaction forces of the limbs were also determined. Due to the temporary failure of the pressure sensors, these measurements were not possible in all animals. 33

34 6.1 Animals 18 female young cattle aged between 8 and 18 months (12.50 ± 2.6 months), which were either kept in loose stalls or on alpine pastures, were examined. The body weight was between 170 and 400 kg (± kg), the Body Condition Score (BCS) (EDMONSON et al., 1989) between 2.50 and 3.75 (3.01 ± 0.46). The height of the young cattle used to measure strength on the treadmill was 118 to 131 cm (± 4.40 cm) (Tab. 1). The claws of the animals were healthy and evenly worn apart from a dorsal wall that was a little too long. The cattle were loaned by the owners for the period of the investigations and then returned to the original farms. 34

35 Tab. 1 .: Overview of identification, age, weight, height, body condition score (BCS) of the young cattle. Ear tag Age [months] Weight [kg] Height [cm] BCS Not measured Not measured Not measured Not measured Not measured Not measured Not measured Not measured Not measured ± ± ± ±

36 6.2 Procedure for the examinations For the examinations, the 18 cattle were divided into 4 groups. The groups of animals each came from the same farm. During the stay at the clinic, the cattle were kept tied up and looked after by the nursing staff and the examiner himself. The animals were rewarded with small amounts of concentrated feed after each new situation. Sedatives were never used. The examinations were carried out within 7 days and had the following sequence: Day 1: Arrival and stabling of the cattle. Day 2: First lead of the animals by the halter in the stable and on the clinic premises. Day 3: Morning: Guided tours on the clinic premises and in the treadmill building. Getting used to the headlights and the noises of the treadmill. First contact with the treadmill and leading across the treadmill. Then fixation on the halter by an assistant standing next to the running surface and starting the treadmill. Increase in speed to 1.2 to 1.3 m / s. Training period of 5-10 minutes each until you recognize a clear, relaxed step. If the animals are too nervous, stop the treadmill, take a break and try again. Reduce the speed of the treadmill, stop the belt, reward the cattle with feed. Afternoon: Further training and first film recordings of the footing process. Day 4: Continue filming and perform force measurement. In the later recordings, the animals are fixed on the halter. A helper is responsible for the control of the treadmill, the hygiene and the motivation of the animals to move forward. Day 5: Functional hoof care. Day 6: Making the film recordings after hoof trimming. Another force measurement. Day 7: The cattle are transported back to their farms of origin. 36

37 6.3 Hygiene on the treadmill Feces and urine on the treadmill made the surface slippery and therefore unusable for these film recordings. A slurry scoop was therefore used to collect the manure and urine. Basically, an attempt was made to stop the treadmill in the given case. If, despite all caution, feces or urine got on the walking surface, they were bound with sawdust and vacuumed with an industrial vacuum cleaner. 6.4 Digital high-frequency camera with PC and software The digital high-frequency camera (Motion Scope PCI 1000S, Redlake Imaging Corporation, Technology Drive, Suite A, Morgan Hill, CA images / s, resolution 320 x 280 pixels, shutter speed 1/1000, exposure time 1/1000 s ) with lens (Cosmicar / Pentax TV-Zoom, 4-48mm, 1:10) was connected to a desktop PC and controlled with the manufacturer's software using a mouse and keyboard. The camera (camera itself, desktop PC, software) was designed by Prof. Dr. Heinz Inglin (Zurich University in Winterthur; project impact analysis) on loan. 6.5 Lighting The treadmill was illuminated with three spotlights focused on the respective limb, each with 220 V, 1000 W and 300 Hz. 37

38 6.6 Film recordings Due to the capacity of the memory, the film sequences were limited to 4 seconds (file size 220 MB) and were saved as * .avi files on an external hard drive. The camera was attached to a photo tripod and was 18 cm above the floor. Since only one camera was used, it had to be positioned for each recording direction. 7 camera positions were used for the four limbs (Fig. 7 a-g). Three positions on the forelegs were sufficient, i.e. an overview from the front and a side view for each limb. Due to the characteristic footprint, it was not possible to create an overview of the hind limbs, so that a lateral and an oblique (angle) view were required. Before taking the recordings, the camera was adjusted to the appropriate limb and the prevailing light conditions. The recording was started as soon as the young cattle had reached the speed (1.2 to 1.3 m / s = km / h) and showed a clear, tactful step. The recording was stopped when four complete movement cycles of the examined limb had been filmed, which in the context of this examination corresponded to the size of the endless memory of 4 seconds (2000 images). For better orientation, the lateral claw was sprayed or coated with spray paint (silver) or black hoof grease. 38

39 a: Front left from side d: Back right from side b: Front right from side e: Back left from side c: Overview of the forelegs from the front f: Back right at the angle from Fig. 7a-g: directions of exposure for the individual limbs. From the side (a, b, d, e), from the front (c), and at an angle of (f, g). g: back left at the angle of

40 Fig. 8: Young cattle on the treadmill, side view. Fig. 9: Young cattle on the treadmill, front view. 40

41 6.7 Hoof care The method according to TOUSSANT RAVEN (1985, 1998) and KUEMPER (2003) was used for claw care. First of all, the inner claw was assessed and, if necessary, shortened. In most of the animals, the outer claws on the hind limbs were larger and protruded somewhat distally. There was no difference in this between the animals that were kept in the loose pen and those that came from the alp. What was striking about the cattle from the loose stalls was the flat bottom, while the animals from the alp had a hollow. The outer claw was adjusted to the inner claw as far as the sole thickness allowed. The sole thickness was checked with the claw examination pliers. If the sole of the outer claw gave way to pressure from the claw examination pliers, it was not worn away any further, even if the level of the inner claw had not yet been reached. Finally, the hollow was created. The same procedure was applied to the forelegs. 6.8 Treadmill and force measurement The treadmill used, a high-speed treadmill (Mustang 2200, Graber AG, Fahrwangen, Switzerland) had an infinitely variable speed setting and could be stopped by an emergency switch in the event of an incident. A total of 18 piezoelectric force measuring sensors (9 on each long side) recorded the vertical forces of all 4 limbs simultaneously (TiF = treadmill integrated force measuring system). The query interval was 433 Hz. Positioning systems mounted parallel to the running surface of the treadmill were connected to the limbs by means of rubber threads (tension 5 N) (2 protractors with one limb each) (Fig. 10). The straps designed for this purpose were attached to the cattle's crook.41 were measured

42 the step frequency, the duration of the support leg and slope leg phases, as well as the vertical impulses. The combination of the treadmill and the measuring system made it possible to standardize and reproduce the basic parameters of the floor, the speed of movement and the duration of the examination. The measurements on the treadmill were carried out on nine animals (cattle 1-9, see Table 1) before and after functional hoof care. Fig. 10: Schematic drawing of the structure of the treadmill used from above and from the side. Force sensors (L + R), frame (frame), tread (belt), base of the tread (platform), damping element (shock absorber), rubber strings, angle measuring system (angular encoders). (WEISHAUPT et al., 2002). Modified. 42

43 6.9 Evaluation of the data The film sequences were viewed with the video software MIDAS Player, (Redlake Imaging Corporation) taking into account the question listed on page 29 and the fusing process was quantified on the basis of the number of images per unit of time. The data of the force measurements were recorded in a spreadsheet program and statistically evaluated with the program SPSS, Version 11.5 (SPSS GmbH Software, Munich, animal experiment permit in accordance with animal protection information 1.04 (classification of animal experiments according to severity levels before the start of the experiment load categories) of the Federal Veterinary Office in Bern the examination classified as unencumbered = degree of severity 0, reported in accordance with Art. 62 para. 1 TSchV and approved by the cantonal veterinary office in Zurich (No. 125/2002)

44 7 RESULTS 7.1 High-frequency cinematography All toes basically showed the same footing pattern: the claws were raised in internal rotation and placed on in slight external rotation. On the pelvic limbs, however, the limbs were brought close to the medians. The footing then took place slightly to the side. Here, too, the toes were placed in external rotation. First contacting claws On the forelegs, 14 animals on the right and 16 on the left made the first contact with the outer claw before claw care. The remaining cattle showed a simultaneous touchdown of both claws with the corresponding limb. After hoof trimming, 17 animals made initial contact with the outer hoof on the right and 16 on the left fore limb. The remaining cattle showed a simultaneous touchdown of both claws with the corresponding limbs (Tab. 2 + 3). Tab. 2: First contacting claw (s) before claw care. Left side Right side Claw (s) lateral medial both lateral medial both forelimbs hind limbs On the hind limbs the first contact of all cattle with the outer hoof was established before hoof care. 44

45 Tab. 3: First contacting claw (s) after claw care. Left side Right side Claw (s) lateral medial both lateral medial both forelimbs hind limb After claw care, only one animal made initial contact on the right hind limb with both claws at the same time, while all the others first touched the ground with the outer claw (Tab. 2 +3) Contact region of the claws that touched down. Lateral claws On the shoulder limbs, seven animals on the right showed contact with the ball of the foot and ten cattle showed a parallel footing before claw care. On the left limb there were ten animals with the ball of the foot and seven cattle that lay down in parallel. One animal showed initial contact with the tip of the claw on both sides. After hoof trimming, 12 animals on the right and 11 on the left walked with the ball of the foot, while the parallel footing of six cattle was shown on the right and seven on the left (Tab. 4). Before hoof trimming, nine cattle made initial contact with the ball of the foot on both hind limbs and eight on both sides by means of parallel feet, while one animal first touched the ground with the tip of the claw on both sides. After hoof trimming, the picture changed as 13 animals on the right and 15 cattle on the left made initial contact with the ball region. The remaining animals (five on the right, three on the left) walked parallel. 45

46 Tab. 4: Regions of first contact on the lateral claws of the limbs in 18 young cattle before and after hoof trimming. Limb First contact Before claw care After claw care right left right left ball of front- parallel tip ball of rear- parallel tip Medial claws On the right fore limb before claw care the claws of five animals landed with the tip, seven parallel and six with the ball first. On the left fore limb there were two animals that first touched down on the tip, eight that were parallel and eight that walked with the ball of the foot. After hoof trimming, seven cattle showed parallel feet on the right fore limb, while eleven animals first walked with the ball of the foot. In the left limb, one cattle showed the footing over the tip, 9 animals walked parallel and 8 animals touched the ball of the foot first (Table 5). On the right hind limbs, the parallel footing of eleven cattle and on the left of twelve cattle were shown before hoof trimming. The rest of the animals walked over the ball of the foot. After hoof care, the footing pattern of the medial claws of the hind limbs changed in favor of the parallel footing. These were shown on the right pelvic limb of 14 and on the left of 15 animals. The rest of the animals walked with the ball of the foot. Neither before nor after hoof trimming was the first contact made with the pelvic limbs via the claw tips. 46

47 Tab. 5: Regions of first contact on the medial claws of the limbs in 18 young cattle before and after hoof trimming. Limb First contact Before claw care After claw care right left right left Ball of front- parallel tip Ball of rear- parallel tip Delayed placement of the medial claw In order to quantify the time delay between the placement of the medial claw in comparison to the lateral claw, the high-frequency cinematographic films that follow functional claw care were used were created, evaluated again. 1 image / s (Avg.Playback rate = 1.0 fps) was selected as the playback speed (Fig. 11). At this speed, the time difference between the contact of the medial claw could be counted exactly and, taking into account the real time duration (500 images / s = 0.002s / image), could be converted in real time as well as statistically evaluated and graphically displayed. On the forelimbs, the time lag (unless people were walking at the same time) was right (± 0.011s) and left (± 0.008s) seconds. The medial claw of the right hind limb touched down on average (± 0.006) seconds, that of the left hind limb on average (± 0.009) seconds later than the lateral claw. The differences between fore and hind limbs were significant (p 0.05). 47

48 Fig. 11: Detailed PC screen views of the MIDAS Player for evaluating the films. Counter for image number (F), zoom function (Z). Time counter in seconds (T), readable to four places after the decimal point. Above: lateral claw back right. Below: medial claw back right. 48

49 7.2 Measurements on the treadmill For technical reasons, it was not possible to take measurements on all of the 18 cattle on the action phases of the limbs in motion and on the vertical impulse before and after hoof trimming. Figure 12 shows an extract (steps 15-18) of the measurement of the vertical impulse of test person no. 8 after hoof trimming. The pressure curves of both fore limbs (fr, fl) and both hind limbs (hr, hl) are shown graphically. The supporting leg phase showed a bimodal maximum on all limbs. The load on the forelimbs (fl, fr) fell more slowly than on the hind limbs (hl, hr). Figure 13 shows the vertical momentum measurement of a limb from one step in detail. The section between X1 and X2 is the phase of elasticity of the limb. In the area of ​​the maximum of elasticity (lowest point between the two peaks) the caution phase (X2) of the movement cycle begins. 49

50 Fig. 12: Excerpt (steps 15-18) from the measurement of the vertical impulse of test person 8 after hoof trimming. Front left (fl), front right (fr), back left (hl), back right (hr). Step number (S), Y-axis: vertical pulse [Ns] (limit: 2500 Ns), X-axis: time [sec]. X 1 X 3 X 2 Fig. 13: Detailed view from Fig. 12 X1 = phase after landing the limb and catching the body weight. Shifting the body's center of gravity downwards. X2 = pushing off the limb with shifting the body's center of gravity upwards. X 3 = center of gravity reached the highest point. Shifting body weight to the contralateral limb. Transition to the slope leg phase. 50