Biomechanical Properties of Bovine Claw Horn
ABSTRACT Inadequate properties of concrete floors in cattle houses seem to be the primary cause of most claw problems, resulting in economic losses and impaired animal welfare. Many claw diseases are sequels of an extreme local overload. In this paper, the mechanical strength of bovine claw horn is studied.The average Young's modulus E determined in bending and compression using a test velocity of 1 mm/min was 382 MPa for horn from the dorsal wall of the bovine claw, 261 MPa for horn from the abaxial wall and 13·6 MPa for bulb horn. There is a significant difference in Young's modulus, hence in stiffness, between dorsal and abaxial wall horn. The average yield stress was 14·3 MPa for dorsal wall horn and 10·7 MPa for abaxial wall horn in a three-point bending test, and 56·0 MPa for bulb horn in a compression test on samples with 100 mm2 surface area and 4 mm height. The registered average Poisson's ratio ν was 0·38. Histological observations could not explain the biomechanical differences between the dorsal and abaxial wall horn. The number of horn tubules per mm2 was smaller and the diameter of the tubules larger in bulb horn than in wall horn.In future research, the yield stress of the horn will be related with the maximum pressures that can occur between cattle claw and concrete floor.
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ABSTRACT: Flight feathers of birds interact with the flow field during flight. They bend and twist under aerodynamic loads. Two parameters are mainly responsible for flexibility in feathers: the elastic modulus (Young's modulus, E) of the material (keratin) and the geometry of the rachises, more precisely the second moment of area (I). Two independent methods were employed to determine Young's modulus of feather rachis keratin. Moreover, the second moment of area and the bending stiffness of feather shafts from fifth primaries of barn owls (Tyto alba) and pigeons (Columba livia) were calculated. These species of birds are of comparable body mass but differ in wing size and flight style. Whether their feather material (keratin) underwent an adaptation in stiffness was previously unknown. This study shows that no significant variation in Young's modulus between the two species exists. However, differences in Young's modulus between proximal and distal feather regions were found in both species. Cross-sections of pigeon rachises were particularly well developed and rich in structural elements, exemplified by dorsal ridges and a well-pronounced transversal septum. In contrast, cross-sections of barn owl rachises were less profiled but had a higher second moment of area. Consequently, the calculated bending stiffness (EI) was higher in barn owls as well. The results show that flexural stiffness is predominantly influenced by the geometry of the feathers rather than by local material properties.Journal of Experimental Biology 02/2012; 215(Pt 3):405-15. · 3.24 Impact Factor
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ABSTRACT: In the treatment of laminitis it is believed that reducing tension in the deep digital flexor tendon by raising the palmar angle of the hoof can reduce the load on the dorsal lamellae, allowing them to heal or prevent further damage. To determine the effect of alterations in hoof angle on the load in the dorsal laminar junction. Biomechanical finite element models of equine hooves were created with palmar angles of the distal phalanx varying from 0-15°. Tissue material relations accounting for anisotropy and the effect of moisture were used. Loading conditions simulating the stages in the stance where the vertical ground reaction force, midstance joint moment and breakover joint moment were maximal, were applied to the models. The loads were adjusted to account for the reduction in joint moment caused by increasing the palmar angle. Models were compared using the stored elastic energy, an indication of load, which was sampled in the dorsal laminar junction. For all loading cases, increasing the palmar angle increased the stored elastic energy in the dorsal laminar junction. The stored elastic energy near the proximal laminar junction border for a palmar angle of 15° was between 1.3 and 3.8 times that for a palmar angle of 0°. Stored elastic energy at the distal laminar junction border was small in all cases. For the breakover case, stored elastic energy at the proximal border also increased with increasing palmar angle. The models in this study predict that raising the palmar angle increases the load on the dorsal laminar junction. Therefore, hoof care interventions that raise the palmar angle in order to reduce the dorsal lamellae load may not achieve this outcome.Equine Veterinary Journal 03/2011; 43(5):536-42. · 2.29 Impact Factor
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ABSTRACT: Pedal claw geometry can be used to predict behaviour in extant tetrapods and has frequently been used as an indicator of lifestyle and ecology in Mesozoic birds and other fossil reptiles, sometimes without acknowledgement of the caveat that data from other aspects of morphology and proportions also need to be considered. Variation in styles of measurement (both inner and outer claw curvature angles) has made it difficult to compare results across studies, as have over-simplified ecological categories. We sought to increase sample size in a new analysis devised to test claw geometry against ecological niche. We found that taxa from different behavioural categories overlapped extensively in claw geometry. Whilst most taxa plotted as predicted, some fossil taxa were recovered in unexpected positions. Inner and outer claw curvatures were statistically correlated, and both correlated with relative claw robusticity (mid-point claw height). We corrected for mass and phylogeny, as both likely influence claw morphology. We conclude that there is no strong mass-specific effect on claw curvature; furthermore, correlations between claw geometry and behaviour are consistent across disparate clades. By using independent contrasts to correct for phylogeny, we found little significant relationship between claw geometry and behaviour. 'Ground-dweller' claws are less curved and relatively dorsoventrally deep relative to those of other behavioural categories; beyond this it is difficult to assign an explicit category to a claw based purely on geometry.PLoS ONE 01/2012; 7(12):e50555. · 3.73 Impact Factor
Biomechanical Properties of Bovine Claw Horn
A. Franck1; G. Cocquyt2; P. Simoens2; N. De Belie1
1 Magnel Laboratory for Concrete Research, Department of Structural Engineering, Faculty of Engineering,
Ghent University, Technologiepark-Zwijnaarde 904, B-9052 Gent, Belgium ; e-mail of corresponding author:
2 Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820
Merelbeke, Belgium ; e-mail: Paul.Simoens@UGent.be
Inadequate properties of concrete floors in cattle houses seem to be the primary cause of most
claw problems, resulting in economic losses and impaired animal welfare. Many claw
diseases are sequels of an extreme local overload. In this paper, the mechanical strength of
bovine claw horn is studied.
The average Young’s modulus E determined in bending and compression using a test velocity
of 1 mm/min was 382 MPa for horn from the dorsal wall of the bovine claw, 261 MPa for
horn from the abaxial wall and 13.6 MPa for bulb horn. There is a significant difference in
Young’s modulus, hence in stiffness, between dorsal and abaxial wall horn. The average yield
stress was 14.3 MPa for dorsal wall horn and 10.7 MPa for abaxial wall horn in a three-point
bending test, and 56.0 MPa for bulb horn in a compression test on samples with 100 mm2
surface area and 4 mm height. The registered average Poisson’s ratio ? was 0.38. Histological
observations could not explain the biomechanical differences between the dorsal and abaxial
wall horn. The number of horn tubules per mm² was smaller and the diameter of the tubules
larger in bulb horn than in wall horn.
In future research, the yield stress of the horn will be related with the maximum pressures that
can occur between cattle claw and concrete floor.
bovine claw, keratin, concrete floor, Young’s modulus, Poisson’s ratio
E Young’s modulus, MPa
N number of samples
? Poisson’s ratio
s stress, MPa
In modern farms cattle are almost uniquely housed on full concrete floors or on pre-fabricated
slatted concrete floors. Despite the many advantages of concrete floors, animals often show
claw diseases which are the direct and indirect effects of the roughness and slipperiness of the
floor (McDaniel & Wilk, 1991). Many claw diseases are caused by traumata of the dermis of
the sole, which are sequels of an extreme local overload (Distl & Mair, 1993). Lameness in
cattle is widely recognised as a major economic and welfare problem (Vermunt & Greenough,
In this paper, the determination of the biomechanical properties of bovine claw horn is
presented. These properties are related with the architecture of the wall and bulb horn, i.e. the
arrangement and spatial relationship of tubular, intertubular and laminar horn cells.
The support and load bearing function of the bovine claw is provided by the epidermal claw
wall (mainly its abaxial portion) and partly by the bulbar part of the sole (Toussaint Raven et
al., 1977). This is especially the case on hard floor surfaces because, due to the axial
inclination of the sole, only the abaxial claw wall margin (solear margin) is in contact with the
substrate. On a soft soil, the sole will contribute more to the load bearing function.
As in most biological tissues, the equine hoof wall material is morphologically non-
homogeneous and mechanically orthotropic. In horses’ hooves there are differences in
biomechanical properties between inner and outer wall segments because of the difference in
histological and cytological organisation of the stratum medium and the regional differences
in water content (Leach & Zoerb, 1983). Similar differences can also be expected in bovine
claws. No significant differences in tensile forces on the nails that fixate the horseshoe could
be found between black and white horse hooves (Runciman et al., 2004), hence no differences
in mechanical strength between dark and light bovine claws are expected.
It has previously been proven that floor surface roughness has a profound effect on the claw-
floor contact area, average contact pressure and maximum local contact pressure (De Belie &
Rombaut, 2003). This study should contribute to better designed floors and improved animal
welfare and economy.
2. Materials and methods
2.1. Horn samples
The biomechanical properties of 46 samples of claw horn from 16 cattle were tested. The data
registered for all samples are summarised in Table 1. The mean weight of the samples was
3.049 g for dorsal and abaxial samples and 0.470 g for bulb samples. The mean age of the
cows the samples were taken from was 37.9 months and the mean weight was 671 kg.
A three-point bending test was used to examine 36 samples of wall horn (21 dorsal and 15
abaxial), and 10 samples of bulb horn were submitted to a compression test. No axial wall
samples were submitted to bending tests because the horn wall in this area was not high
enough to make a sample with sufficient length. The choice of the tests reflects the way the
claws are loaded in living animals.
The horn samples were cut from the claws of freshly slaughtered cows by m eans of an
oscillating saw (Figs 1 and 2). The underlying soft dermal structures were removed
The horn samples were stored in small sealed plastic containers to prevent dehydration. The
samples were then kept at 7°C until further refinement with a planing machine (with a slowly
moving chisel). This equipment was used to make a sample with smooth, parallel surfaces and
with precise dimensions (deviations of 0.1 mm only). This procedure was requisite because all
samples needed to have the same cross section for bending tests and the same surface area for
The dorsal and abaxial wall samples for the bending tests were 10 mm broad, 4 mm thick and
the length ranged between 45 and 60 mm, exceeding the 40 mm span between the supports of
the test machine. In the samples, the horn tubules were parallel with the length axis of the