Kinetic effect of different ground conditions on the sole of the claws of standing and walking dairy cows.

For the first time, we analyzed the direct kinetic effects of concrete and rubber flooring on the soles of live dairy cows' claws while standing and walking. Ten adult dairy cows were equipped with foil-based pressure sensors (HoofSystem, Tekscan Inc., Boston, MA) under their left hind leg using a leather claw shoe. These sensors captured parameters of pressure distribution and vertical ground reaction forces while the cows walked on the 2 tested flooring types. The mean pressure was 15.1 to 21.1% lower on rubber flooring compared with concrete; mean pressure values (± standard deviation) were 36.32 ± 7.77 N/cm2 for static measures and 57.33 ± 11.77 N/cm2 for dynamic measures. We observed an even more obvious relief on rubber flooring in the maximum pressure loads, which were 30.1 to 32.7% lower on rubber flooring compared with concrete; mean pressure values (± standard deviation) were 98.79 ± 14.49 N/cm2 for static measures and 150.45 ± 20.87 N/cm2 for dynamic measures). The force-time curves of the dynamic measures essentially showed biphasic curve progression, with local peaks at 29 and 79% of the stance phase. However, we found considerable differences in curve progression between individuals and between the lateral and medial claws, which may be verified in further investigations with more animals. The study showed a noticeable reduction in mechanical load during standing and walking on rubber flooring compared with concrete.

Does the range of motion in the bovine interphalangeal joints change with flooring condition? A pilot study using biplane high-speed fluoroscopic kinematography.

This study had 2 objectives. The first objective was to investigate motion patterns and the range of motion of the bovine proximal and distal interphalangeal joints on concrete during the stance phase. The second objective was to determine whether the range of motion and the locomotive stability of the interphalangeal joints differ on concrete and 3 different commercially available rubber mats (Karera, Kura, and Pedikura; Kraiburg Elastik GmbH & Co. KG, Tittmoning, Germany). Biplane high-speed fluoroscopic kinematography (72 ± 2.5 kV and 112.5 ± 12.5 mA, refresh rate 500 frames per second, shutter 0.5 ms) was applied to record 1 stance phase of the right forelimb of 2 Holstein Friesian heifers (15 mo old, 440 ± 10 kg; ± standard deviation) on each flooring. Three-dimensional digital animations were generated with a marker-supported manual animation technique based on the recordings and computer tomographic bone models. The mean maximum range of motion of each of the 4 interphalangeal joints in terms of flexion/extension, abduction/adduction, and internal/external rotation were calculated as well as the mean number of local extrema as a measure of stability during the stance phase. The main degree of freedom in all interphalangeal joints was flexion and extension with a range of motion of 17.7 to 25.9°. The second largest degree of freedom differed between abduction/adduction (7.7-10.0°) and internal/external rotation (6.5-9.6°) depending on the joint. Remarkably, although smaller, these extrasagittal directions still contribute to the overall motion to a considerable degree. In addition, the interphalangeal joints of the lateral digit showed a tendency to move less during the stance phase than their medial counterparts. Comparing concrete to the rubber mats, the interphalangeal joints tend to have to cover a larger range of motion on concrete with the exception of the distal interphalangeal joint in terms of flexion/extension. The unyielding surface of concrete seems to force the flexible parts of the animal-ground-interaction into extended motion. Furthermore, there tends to be more instability in all 3 degrees of freedom in all 4 joints on concrete, implying a greater effort of the soft tissues to achieve a balanced motion. Detailed biomechanical research contributes to the development of adequate flooring systems by evaluating the mechanical strain on claws and joints and working toward lameness prevention and thus animal welfare.

Effect of different flooring types on pressure distribution under the bovine claw - an ex vivo study.

BACKGROUND: Mechanical interactions between hard floorings and the sole of bovine claws can be reasonable to cause traumatic claw lesions. In this ex vivo study, the direct kinetic impact of concrete and three types of rubber mats on the sole of dairy cattle claws was analyzed. In order to apply uniform loads, isolated distal hind limbs of adult Holstein Friesian dairy cows were functionally trimmed according to the Dutch method and attached to a load applicator. Kinetic data were recorded using a thin, foil-based pressure measurement system (Hoof™ System, Tekscan®). RESULTS: On concrete, the load distribution between the lateral and medial claw was less balanced than on the rubber floorings. The loaded area was significantly smaller on concrete (32.2 cm2) compared to all rubber mats (48.3-58.0 cm2). Average pressures (Pav) and maximum pressures (Pmax) were significantly higher on concrete (Pav 44.7 N/cm2; Pmax 130.3 N/cm2) compared to the rubber floorings (Pav 24.9-29.7 N/cm2; Pmax 71.9-87.2 N/cm2). Pressure peaks occurred mainly in plantar and abaxial parts of the lateral claw and in apical and plantar regions of the medial claw. Load distribution displayed a widely unloaded slope region, but considering the pressure distribution under the claw, none of the zones showed a generally lower pressure exposure. CONCLUSIONS: Altogether, rubber floorings lead to a significant mechanical relief of the sole compared to concrete. Furthermore, relevant differences between the tested rubber mats could be determined. Therefore the used system may be applied to compare further flooring types.

Validation of 2 noninvasive, markerless reconstruction techniques in biplane high-speed fluoroscopy for 3-dimensional research of bovine distal limb kinematics.

Lameness severely impairs cattle's locomotion, and it is among the most important threats to animal welfare, performance, and productivity in the modern dairy industry. However, insight into the pathological alterations of claw biomechanics leading to lameness and an understanding of the biomechanics behind development of claw lesions causing lameness are limited. Biplane high-speed fluoroscopic kinematography is a new approach for the analysis of skeletal motion. Biplane high-speed videos in combination with bone scans can be used for 3-dimensional (3D) animations of bones moving in 3D space. The gold standard, marker-based animation, requires implantation of radio-opaque markers into bones, which impairs the practicability for lameness research in live animals. Therefore, the purpose of this study was to evaluate the comparative accuracy of 2 noninvasive, markerless animation techniques (semi-automatic and manual) in 3D animation of the bovine distal limb. Tantalum markers were implanted into each of the distal, middle, and proximal phalanges of 5 isolated bovine distal forelimbs, and biplane high-speed x-ray videos of each limb were recorded to capture the simulation of one step. The limbs were scanned by computed tomography to create bone models of the 6 digital bones, and 3D animation of the bones' movements were subsequently reconstructed using the marker-based, the semi-automatic, and the manual animation techniques. Manual animation translational bias and precision varied from 0.63 ± 0.26 mm to 0.80 ± 0.49 mm, and rotational bias and precision ranged from 2.41 ± 1.43° to 6.75 ± 4.67°. Semi-automatic translational values for bias and precision ranged from 1.26 ± 1.28 mm to 2.75 ± 2.17 mm, and rotational values varied from 3.81 ± 2.78° to 11.7 ± 8.11°. In our study, we demonstrated the successful application of biplane high-speed fluoroscopic kinematography to gait analysis of bovine distal limb. Using the manual animation technique, kinematics can be measured with sub-millimeter accuracy without the need for invasive marker implantation.

Pregnancy effects on distribution of progesterone receptors, oestrogen receptor alpha, glucocorticoid receptors, Ki-67 antigen and apoptosis in the bovine interplacentomal uterine wall and foetal membranes.

Until recently, studies dealing with the uterus of the pregnant cow focus primarily on the placentome or on early and late pregnancy. Thus, there is a paucity of information about many aspects of the interplacentomal uterine wall including adherent foetal membranes. Corresponding tissue specimens were collected at the slaughterhouse and in animals undergoing premature caesarean section. Two specimens per month of pregnancy were assessed immunohistochemically for progesterone receptors, oestrogen receptor alpha and glucocorticoid receptors, Ki-67 protein and TUNEL procedure was performed. The latter two methods were employed in three animals each per months 1 and 2, 3 and 4, 7 and 8 and in six animals undergoing caesarean section at days 274 and 275 post insemination or during spontaneous labour. Results indicate that proliferation and apoptosis are of minor importance for tissue homeostasis since both can histochemically be detected only sporadically. Thus, at the sites investigated here, cellular hypertrophy plays an important role for tissue growth during pregnancy. Progesterone receptors, oestrogen receptor alpha and glucocorticoid receptors, however, exhibit cell type and pregnancy stage specific distribution patterns within the tissues assessed. Progesterone receptor immunoreactive scores remained fairly unchanged during pregnancy. Oestrogen receptor alpha scores, however, generally decreased and glucocorticoid receptors increased with ongoing gestation. Progesterone receptors and oestrogen receptor alpha were present in endometrial stroma and in myometrial smooth muscle cells during whole pregnancy. Oestrogen receptor alpha was detectable during whole pregnancy also in uterine glands. Progesterone receptors were, however, present at a very low level at the latter site only during months 1-3 and 6-9. Oestrogen receptor alpha and glucocorticoid receptors may also mediate uterine blood flow since they were present in the tunica media of uterine blood vessels. Results of the present study indicate, that progesterone and its receptor play an important role during whole gestation, mainly for uterine quiescence. Glucocorticoids and their receptors - possibly in cooperation with oestrogens and decreasing amounts of the oestrogen receptor alpha - should trigger processes initiating parturition, such as endometrial prostaglandin production. Further studies - including the periparturient period - should help to understand the exact role of the extraplacental compartment of the uterine wall for the initiation and progress of parturition.

Membrane-coating granules and the intercellular cementing substance (membrane-coating material) in the epidermis in different regions of the equine hoof.

This study aimed to carry out a comprehensive morphological examination of the structure and ultrastructure of the membrane-coating granules (MCG) and membrane-coating material (MCM) common to all hoof segments as well as segment-specific features in the MCG and MCM regarding their synthesis, structure and biochemical composition. Tissue samples from the hooves of the left front and right hind limb of 20 adult riding horses were used. Samples were preserved and embedded for histological routine methods as well as for histochemical techniques and tracer techniques for light and electron microscopy. The MCM shows a segment-specific structure, biochemical composition and function, which were demonstrated for the different parts of the hoof. The MCM and its properties are related to the segment-specific horn quality. Besides intercellular structural factors the MCM is of major importance for the structural integrity and the biomechanical properties of the hoof horn. The physiological structure and composition of MCM provides explanation for the existence of clinically well-known sites of predilection for hoof disorders such as the White Line Disease. Alterations of the MCM play a role in dysfunction and diseases of the hoof epidermis; they are particularly involved in the pathogenesis of infectious diseases of the hoof.

Invited review: formation of keratins in the bovine claw: roles of hormones, minerals, and vitamins in functional claw integrity.

Keratins are the characteristic structural proteins of the highly cornified epidermis of the skin, feathers, and hoof. Keratin proteins provide the structural basis for the unique properties of the biomaterial horn and its protective function against a wide range of environmental factors. Hoof horn is produced through a complex process of differentiation (keratinization) of epidermal cells. Formation and biochemical binding of keratin proteins and synthesis and exocytosis of intercellular cementing substance (ICS) are the hallmarks of keratinization. It is finalized by the programmed death of the living epidermal cells, i.e., cornification, that turns the living epidermal cells into dead horn cells. The latter become connected by the intercellular cementing substance. The functional integrity of hoof horn essentially depends on a proper differentiation, i.e., keratinization of hoof epidermal cells. Keratinization of hoof epidermis is controlled and modulated by a variety of bioactive molecules and hormones. This process is dependent on an appropriate supply of nutrients, including vitamins, minerals, and trace elements. Regulation and control of differentiation and nutrient flow to the epidermal cells play a central role in determining the quality and, consequently, the functional integrity of hoof horn. Decreasing nutrient supply to keratinizing epidermal cells leads to horn production of inferior quality and increased susceptibility to chemical, physical, or microbial damage from the environment. A growing body of evidence suggests that hormones, vitamins, minerals, and trace elements play critical roles in the normal development of claw horn and correct keratin formation.

Proliferation and apoptosis in bovine placentomes during pregnancy and around induced and spontaneous parturition as well as in cows retaining the fetal membranes.

Placental growth can be achieved by either cellular proliferation or hypertrophy. Tissue regeneration and the nutrition of the fetus via embryotrophe require high rates of cellular turnover and the so-called pre-term 'maturation' of the placenta is correlated with a reduction of maternal crypt epithelial cells. Placentomes of 45 pregnant cows were collected from an abattoir to assess the role of proliferation and apoptosis in placental physiology and pathology. Placentomes were also taken from five cows undergoing premature Caesarean section and from ten naturally calving cows immediately after the expulsion of the fetus. Five of these animals had not released the fetal membranes after 12 h. Tissue sections of placentome were assessed for the Ki-67 protein; the TUNEL procedure was performed and verified by transmission electron microscopy. The maternal crypt epithelium and the fetal chorionic epithelium had a higher percentage of Ki-67-positive cells than the stroma. The percentage of Ki-67-positive cells increased significantly during pregnancy in fetal chorionic epithelium and was significantly decreased in fetal chorionic epithelium and maternal crypt epithelium after the expulsion of the fetus in comparison with tissue from month 9 of pregnancy. The number of apoptotic cells increased significantly during pregnancy in maternal crypt epithelium, maternal stroma and fetal chorionic epithelium as detected in slaughtered animals. Significantly more apoptotic fetal chorionic epithelial cells were found in animals retaining their fetal membranes in comparison with prepartum cattle during month 9 of pregnancy, at premature section and in animals releasing the fetal membranes completely. The results strongly indicate that bovine placentomes have cell type-specific rates of cellular turnover reflecting tissue growth, embryotrophe and placental maturation. Retention of fetal membranes is characterized by a large number of fetal chorionic epithelial cells undergoing apoptosis immediately after the expulsion of the fetus. This finding indicates that incomplete maturation of placentomes plays an important role in fetal membrane retention and that massive apoptosis after the expulsion of the fetus should be the consequence of diminished blood supply to the uterus, as verified in a recent study.

Pododermal angioarchitecture of the bovine claw in relation to form and function of the papillary body: a scanning electron microscopic study.

The region-specific angioarchitecture of the bovine pododerma was examined using systematic scanning electron microscopy of micro-corrosion casts of juvenile and adult bovine claws. Particular emphasis was laid on the demonstration of specialised vascular structures such as arteriovenous anastomoses. Comparing the results of main and dew claws, respectively, of juvenile and adult claws, a relation between burdening of the claw and density and differentiation of the pododermal papillary and lamellar blood vessels was detected. The results suggest a possible influence of body weight (or age) and weight-bearing on the formation and vascularisation of the pododermal papillary body. The lamellar and papillary microvascularisation and microcirculation are discussed.

Prevention of venous graft sclerosis with clopidogrel and aspirin combined with a mesh tubing in a dog model of arteriovenous bypass grafting.

OBJECTIVE: to investigate the effect of clopidogrel combined with aspirin or aspirin alone on fibromyointimal hyperplasia (FIMH) in a bypass model with native vein grafts (NVG) and biocompound grafts (BCG). DESIGN: twelve Beagle dogs were randomised into two equal groups. In each animal NVG and a BCG were interposed in the common carotid arteries. Postoperatively, Group 1 received clopidogrel (200 mg/d) and aspirin (100 mg/d) and Group 2 received aspirin (100 mg/d) alone. METHODS: the BCG was constructed by sheathing the ipsilateral jugular vein with highly flexible metal mesh tubing. After 30 days the grafts were harvested and pressure fixed. FIMH was determined by morphometry. RESULTS: the average wall thickness of the BCG was significantly lower than that of the NVG in both groups (0.26 (SD)0.02 mm vs 0.47 (SD)0.15 mm, p = 0.04 and 0.28 (SD)0.05 mm vs 0.70 (SD)0.29 mm, p = 0.01, respectively). For BCG treated with aspirin, the wall cross section area was lower (5.0 (SD)0.6 mm(2)vs 9.1 (SD)3.3 mm(2), p = 0.02) and the lumen larger (25.2 (SD)5.9 mm(2)vs 9.7 (SD)3.4 mm(2), p < 0.01) than for the NVG. There was also a difference in the lumen cross section area of the NVG, which was larger after combined therapy with clopidogrel and aspirin (17.9 (SD)7.8 mm(2)vs 9.7 (SD)3.4 mm(2), p = 0.04). CONCLUSIONS: in this dog model the sheathing of vein grafts effectively prevents FIMH following bypass surgery. Clopidogrel is effective in NVG.

Butyric acid stimulates rumen mucosa development in the calf mainly by a reduction of apoptosis.

In ruminants the stimulation of papillar growth by butyric acid is well described but effects on mitosis and apoptosis are not known. To clarify the effect of short chain fatty acids three groups of three calves received a basic ration of 100 g hay per day for 6 weeks and additionally milk replacer. From these, two groups were fed with increasing amounts of the salts of either propionic acid (53 to 390 g) or butyric acid up to (54 to 326 g). The control group instead received an additional isocaloric amount of milk replacer. Mitosis was characterized by Ki67 immunoreactivity, apoptosis by a modified TUNEL assay and by electron microscopy. The feeding regimes led to significant differences of papillar length, increasing from 1.0 mm (controls) to 2.2 mm (propionic acid) and 4 mm (butyric acid). This enlargement was partly explained by an increased mitotic rate for the two fatty acid groups. The difference between the fatty acid groups was mainly explained by different apoptotic rates which were only one third for butyric acid compared to propionic acid (P < 0.001). In conclusion, butyric acid is a specific inhibitor of ruminal apoptosis in vivo.

Three-dimensional appearance of bovine epidermal keratinocytes in different stages of differentiation revealed by cell maceration and scanning electron microscopic investigation.

The epidermis of the modified skin of the bovine hoof is a highly mechanical loaded tissue. Consequently, all cell connections have to withstand high mechanical forces. As an adaptation to this stress, the epidermal keratinocytes show characteristic surface modifications. Furthermore, the tissue displays a complex three-dimensional architecture which is difficult to appreciate from histological sections. SEM-observation of macerated tissue samples is a fast, easy to use and reliable tool to receive three-dimensional information about the appearance and spatial relationship of cells within a tissue. Using cell maceration, the aim of this study was to separate individual as well as smaller groups of keratinocytes in order to reveal the formations of the cell surface, the appearance of individual cells and the spatial relationship of cells within the tissue. A NaOH maceration method described in literature was modified and applied to tissue samples from the wall and bulbar segment of the hooves of six cows. The method facilitated separation between the epidermal cells. Single cells as well as cell groups were available for SEM observation which revealed a three dimensional appearance characteristic for different stages of differentiation of the keratinocytes. The observed findings suggest that throughout the process of differentiation the surface modifications provide the basis for a stable cell to cell adhesion which is established by desmosomes and the intercellular cementing substance. Additionally, the broadened cellular surface area is related to the supply of the highly metabolic active living epidermal cells with nutrients and oxygen. Longer cell processes typically found in the central surface area of the keratinocytes may carry gap junctions and may be involved in cell communication. This, however, has to be clarified by further electron microscopic studies. The demonstrated appearance of individual cells and the complex architecture enable the hoof epidermis to fulfill its unique biomechanical functions.

How structures in bovine hoof epidermis are influenced by nutritional factors.

The structure of the hoof epidermis is the link between nutrition and horn quality. The aim of this study was to demonstrate the relationship of single structures in the process of keratinization and cornification of bovine hoof epidermis to certain nutritional factors such as lipids, minerals and vitamins. Furthermore, we wanted to show the structural changes in the dyskeratotic epidermis caused by an insufficient supply of keratinizing epidermal cells. For our study we used samples of hoof epidermis from 25 dual-purpose dairy cattle, with ages ranging between 2.5 and 4 years. We also obtained a complete set of hooves from a biotin-deficient calf. All samples were investigated by light and transmission electron microscopy, using routine methods as well as histochemical and enzyme-histochemical techniques. We focused on epidermal structures that have a major influence on horn quality and are known to be related to single nutritional factors. The strength of the keratin filament bundles is determined by their cross-linking via sulphur-containing amino acids. Essential fatty acids are required for the synthesis of an intercellular cementing substance connecting the horn cells and establishing a permeability barrier in the stratum corneum. Minerals, in particular calcium, are essential for activation of enzymes that are a prerequisite for physiological keratinization and cornification. Furthermore, vitamins such as biotin are essential in the metabolism of the keratinizing epidermal cells.

Microvasculature of the bovine claw demonstrated by improved micro-corrosion-casting technique.

A new and improved technique for microvascular corrosion casting was developed and verified by examination of corrosion casts of 90 bovine limbs. The described technique renders a complete filling of the vasculature of the claw even in regions that hitherto proved to be difficult regarding completeness of filling such as the dorsal area of the claw. This is demonstrated by an exemplary examination of all regions of the claw. The advantages and disadvantages of the new method are discussed.

[Morphologic detection of Bacillus cereus in blank cartridges]. / Morphologischer Nachweis von Bacillus cereus in Knallkartuschen.

Wound infections after gunshot wounds from live ammunition can produce serious complications. It is well known that projectiles per se are neither sterile nor does their firing cause sterilization. The germs on the surface of a projectile enter the body together with the projectile and are thus introduced into the wound together with skin bacteria. However it is less known that wound infections can occur in wounds caused by the gas jet from blank ammunition (mainly from shots at very close range). In such ammunition without a projectile, the propellant particles are usually contaminated with bacteria which find their way into the wound together with skin germs. In previous investigations, we have microbiologically detected the species Bacillus cereus in the propellant of blank cartridges. In the present study, we have applied scanning electron microscopic methods to find out which areas of the blank cartridges are colonized by these bacteria. For this purpose 20 blank cartridges, each from 4 different manufacturers, were electronmicroscopically examined. B. cereus only found on the surface of intact nitrocellulose particles but not in the interior of broken prepared propellant particles. Bacterial structures were not morphologically identified on black powder particles.

Subsurface crypts and interstitial cells in the ovary of the seal (Phoca vitulina vitulina): light and electron microscopic findings.

This morphological study on the ovary of the seal focuses on two structures of special interest: the subsurface crypts and the interstitial cells. Ovaries from 110 seals (from 1,5 months to 12 years) were used. Most of the seals of our study originated from German North Coast, a few from Island. The ovaries were examined by light microscopic as well as by transmission and scanning electron microscopic techniques. The seal's ovary conforms to the basic structure of the ovary of other mammalian species. However, the surface epithelium cell layer lowers itself into an epithelium lined - broadly branching system of subsurface crypts. The size and extent of these crypts and the proliferation of the epithelium appear to be mainly related to the reproductive activity. The ultrastructure of crypt epithelium cells indicates a remarkable metabolic activity. In juvenile ovaries cell buds proliferate from the crypt epithelium and grow as plug-like strands into the cortical stroma. These cells show ultrastructural changes during their proliferation and appear to transform into steroid producing interstitial cells. In the adult seal the interstitial cells are completely differentiated established and, according to their origin, can be divided into epithelial and fibroblastic interstitial cells. It is suggested that a major function of the crypts is the formation of the ovarian blastema with particular reference to ovarian interstitial cells. The intensive proliferation of interstitial cells is in agreement with the extraordinary high level of 350 pmol estrogen/l blood serum.

Rate of keratinization of the wall segment of the hoof and its relation to width and structure of the zona alba (white line) with respect to claw disease in cattle.

OBJECTIVES: To determine contribution of the wall segment of bovine cattle hoof to horn production, and relevance of structural differences of the wall segment and its horn production rate to claw disease. DESIGN: Epidermis and papillary body of the wall segment were examined by mesoscopy, light microscopy, and transmission and scanning electron microscopy. Morphometry of the entire length of the zona alba was examined, and the horn production rate of the wall segment was calculated. ANIMALS: Mixed-breed, dual purpose (beef and dairy) cattle of either sex, and young (20 months) Holstein-Friesian beef bulls. PROCEDURE: Blocks of a strip of the hoof from the coronary segment to the sole margin, including epidermis and dermis, were prepared for light and transmission electon microscopy. Prepared specimens of the wall-sole border were examined by scanning electron microscopy. Morphometry was performed on the outer, middle, and inner parts of the zona alba structures on unfixed horn specimens of beef bull claws. After removal of the zona alba specimens, the claw was removed and the proximodistal extent of the epidermal leaflets was measured and analyzed statistically. RESULTS: Horn production increased in the distal half of the wall segment, was greatest at the wall-sole border, and highest above the abaxial end of the zona alba. High horn production resulted in an incompletely keratinized, softer horn. CONCLUSIONS AND CLINICAL RELEVANCE: High horn production at the zona alba increases susceptibility to vascular disturbance. Claw dyskeratoses appear first in areas of high horn production, areas which are also subject to a greater frequency of claw lesions.

[Structural factors influencing the horn quality and predilection sites for diseases at the bottom surface of the bovine hoof]. / Strukturelle Faktoren mit Einfluss auf die Hornqualität und Prädilektionsstellen für Erkrankungen an der Fussungsfläche der Rinderklaue.

The quality of the horn of the cattle hoof varies in the different segments of the ground surface adapted to weight bearing. Horn quality is influenced by the following main factors: the keratin proteins as the most important intracellular factor, the intercellular cementing substance as the intercellular factor, and the architecture of the cluster of horn cells, i.e. the arrangement of horn cells in tubular and intertubular horn. Differences in the structure and composition of these factors and their respective combination determine the different degrees of hardness of hoof horn, which are even palpable. In special places, as i.e. the white zone, the combination of all these above-mentioned factors determines sites of predilection for diseases of the cattle hoof like white line disease.