This thesis is an investigation of the prevalence of, and factors associated with, hock, knee, and neck injuries on dairy cattle in Canada. Tie-stall (n = 100) and free-stall farms (n = 90) were visited in Quebec, Ontario, and Alberta, Canada. Cows were scored for hock (tarsus), knee (carpus), and neck injuries on a 3 or 4-point scale combining the attributes of hair loss, broken skin, and swelling. Animal-based and environmental measures were taken which were hypothesized to be risk factors for injury. On tie-stall farms the mean herd-level prevalence of hock, knee, and neck injuries was 56, 43, and 30%, respectively. On free-stall farms the mean herd-level prevalence of hock, knee, and neck injuries was 47, 24, and 9%, respectively. Having sand stall bases, feed rail heights above 140 cm and managing cows to reduce slips and falls were associated with reduced injury prevalence. / Dairy Research Cluster (Dairy Farmers of Canada, Agriculture and Agri-Food Canada, Canadian Dairy Commission)

Increased rates of involuntary culling as a consequence of poorer health and fertility had led to the conclusion that dairy cows appear to be less “robust” or adaptable than in the past. A way to address these concerns in breeding programs could be to select for health and welfare by including appropriate traits in a broader breeding index. However, it is important to consider any consequences that such breeding goals may have on dairy cow temperament and welfare. There were two phases to this study. The main objective of phase I was to develop tests for measuring responsiveness to humans and novelty, aggression at the feedface and sociability in dairy cows for use on commercial farms. To allow these tests to be used on commercial farm, they must be short in duration, non-invasive and not disruptive to the daily farming routine, while at the same time allowing comparisons between an individual cow’s responses in a number of similar situations. Results from this study suggested that a standardised human approach test and a stationary visual object are reliable tests for measuring responsiveness of dairy cows to changes in their environment. Measuring behaviour at the feedface proved to be an effective measure of between cow aggression. Inter-animal distance, position in relation to the herd, behavioural synchrony and presence at the feedface proved accurate measures of sociability. The remaining part of the study (Phase II) focussed on assessing how the implantation of a breeding index can affect the temperament of dairy cows on commercial farms. The tests developed were then recorded on 402 first lactation Holstein-Friesian dairy cows selected from sires that scored high (HI) and low (LO) for robustness (health, fertility and longevity traits) to produce two treatment groups on 33 commercial farms. For the purpose of this thesis, only the results from the assessment of aggressiveness are presented. Continuous focal sampling was used to record aggressive behaviour during feeding of the HI and LO cows within the herd. Cows from the HI group were involved in more aggressive interactions, initiated more aggression and received more aggression than cows from the LO group. There was a strong influence of management factors influencing aggression such as the quality of stockmanship, feedface design and nutrition. In conclusion, daughters from sires scoring high for robustness may be expressing a greater ability to maintain position at the feedface during an aggressive interaction. This highlights the importance of assessing the correlated effects of selective breeding, in this case for robustness, on behavioural traits.

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