The aim of this thesis was to provide knowledge to the dairy industry about HT and to provide science based recommendations on if LIT or BIG model is more effective at preventing lameness and lesions. Based on the results from this thesis it was shown that the HT process is associated with behavior changes and causes an acute stress response and decreases milk yield. Based on the results of these objectives the acute stress response is due to restraint, not the actual removal of horn during the HT process. The decrease in milk yield that was observed after HT needs further research to determine what effect disruption of the cow's day with no access to feed has on milk yield. In addition, we compared a HT technique that is currently used in the industry to an adaptation that increased the modeling on the weight bearing claw. Based on a subset analysis, this adaptation was protective for hoof horn lesions and lameness for cows trimmed at the end of their first lactation. However, there was no difference between the two HT techniques for long term milk yield and culling risk. The final conclusion was BIG model is more effective at preventing hoof horn lesions than the LIT model, and there was no evidence that BIG model (vs LIT) was detrimental to the welfare of the cow based on milk yield and culling risk.
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