Characteristics of Claw Horn Microstructure and the Effect of Flooring Systems on Horn Quality

Introduction:  Interactions between horn quality and flooring systems significantly impact on claw health. Poor horn quality is associated with reduced milk yield, painful lesions or slaughtering. Horn quality is determined by horn cells, intercellular cement and hoof horn architecture, i.e. the structure and arrangement of the horn tubules. Soft and elastic flooring systems have been reported to have a positive influence on the microstructure of hoof horn. Aims:  We wanted to correlate the microstructure of claw horn to the horn quality in a large number of samples and detect influences of the flooring system on hoof horn microstructure. Methods:  Samples were obtained from two different studies: 40 cows from Hohenheim/Germany kept on slatted floor and subsequently on rubber mats for 4 months; 1000 cows from 11 farms in Luxembourg, kept on concrete floor. From all samples 7 μm-sections were cut and stained with the PAS-reaction. Morphometry was done with the LuciaG©-software (Nikon GmbH, Dusseldorf, Germany) and statistical analysis was performed with SPSS® (SPSS Inc., Chicago, IL, USA). Parameters measured were area, minimal and maximal diameter of both medulla and cortex of horn tubules. Statistical analysis included: tubules per visual field, area per visual field, total medulla area, total cortex area and the limiting values of diameters. Results:  Luxembourg samples showed consistency of tubule-parameters between both dates; all farms showed an average number ranging from 13.36 to 14.79 tubules per visual field. Hohenheim horn from the hard flooring showed 19.9 and horn of the same animals kept on rubber floor showed 20.5 tubules per visual field. Maximum diameter of hard-floor horn is 55 μm whereas 45 μm in animals kept on rubber floor. Conclusions:  The results show that genetic/individual differences take smaller influence on horn quality than housing systems. These outcomes provide evidence for the economical and animal welfare benefit of soft and elastic flooring systems. Further research will focus on correlation of biodata, such as physiological state, lactation, age, and claw horn microstructure. This work was supported by Biopsytec/Rheinbach.