The study investigated healthy claw samples from cross-bred heifers aged around 20 months. Histological studies adopted a novel sectioning approach along planes parallel to the wall, identifying dynamics of the keratinisation process, localisation of elastic fibres and anatomical features of cap papillae and horn. Structural molecules were investigated immunohistochemically, including cytokeratins, cytokeratin 14 (CK14) and β-actin. The results showed patterns of suprabasal keratin deposition and loss of signal for CK14 and β-actin markers in differentiating keratinocytes. Localisation of vimentin provided evidence of mesenchymal cells in laminar dermis. Transforming growth factor β1 (TGFβ1) and connective tissue growth factor (CTGF) were investigated immunohistochemically, by <i>in situ</i> hybridisation and RT-PCR. Immunohistochemistry showed signals in the dermis and epidermis, with mRNA presence solely in the dermis and high synthesis rates on comparison with internal control. Mean expression levels were higher in summer than in winter. Collagen I (COL1A2), elastin, estradiol receptor β, cyclin A and B were also investigated by RT-PCR and consistently amplified. Tissue cultures were carried out in order to study TGFβ1, CTGF and COL1A2 expression by RT-PCR in tissue explants incubated in presence of TGFβ1. Results identified a time effect but absence of a concentration effect. Proteomic analysis of fractions extracted from incubated and non-incubated (control) explants showed significant differences for a number of spots, mainly in the keratin region of the electrophoretic gels. In conclusion, the study has provided novel information on molecules of importance in the structure and regulation of epidermal and dermal cells and dermal extracellular matrix in the laminar region of the bovine claw.

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on June 11, 2009). Includes bibliographical references.

The forces and pressures applied to the hooves of Friesian cattle during gait were investigated using a combined force plate and pedobaroscope. Studies included those concerned with changes in loads and pressure with increasing live weight, flooring surface, stages of pregnancy and differences in gait with lameness. The forefeet carried significantly greater loads (i.e. equivalent to 60 per cent of body weight) than the hind feet (i.e. equivalent to 50 per of body weight), but no difference in load was observed between contralateral limbs. In most cases no significant difference was observed in contact area between feet. However with increasing live weight hoof-ground contact area increased at a rate exceeding that expected from allometry. The obtained relationship between area (A) and live weight (m) was A = 10.96 m<SUP>0.96</SUP>. Pressure did not increase significantly with live weight. No significant decrease in contact area or increase in pressure was observed with a simulated slot, of 12 mm width, in the floor. During pregnancy the load distribution did not change significantly, though pressures were observed to increase slightly on all feet in the pre-partum period. The vertical ground reaction and horizontal fore and aft force-time curves of lame cows were different to those obtained from non-lame cows. The force-time curves of the non-lame limbs of the lame cattle were also modified. It was concluded that the heel region was compressed of the inter-digital space increased to increase the solear ground contact with increasing load, to reduce applied pressure. This would reduce the risk of pressure-induced injury and lameness. The load distribution during pregnancy did not explain the higher incidence of lameness on the hind feet at this time and other factors may be implicated. Changes in applied forces on limbs with lameness may act to alleviate pain. The forces applied to the non-lame limbs may compensate for the change in load on the lame foot or act to further alleviate pain. Further work is suggested to relate the risk of injury and lameness on different floor types to the applied loads and pressures.

Call number: LD2668 .T4 1978 P38 / Master of Science

Thesis (M. Agr. Sc.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (Ph. D.)--Michigan State University. Dept. of Animal Science, 2006. / Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 127-153). Also issued in print.

Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisor: Eugene G. Mueller, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

Digitized by Kansas Correctional Industries

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Robert M. Dyer, Dept. of Animal and Food Sciences. Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Animal and Dairy Sciences. / Title from title screen. Includes bibliographical references.