Dairy cattle lameness in New Zealand : defining the problem and investigating preventative and treatment strategies : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University

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Massey University
Listed in 2024 Dean's List of Exceptional Theses
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Lameness is ranked in the top three most important animal health diseases in dairy cattle worldwide, and has significant negative impacts on animal welfare, farm productivity, greenhouse gas emissions and the social license to dairy farm. Despite this, there has been an under-investment in research into lameness in New Zealand over the past three decades. This thesis aimed to fill some of the gaps in knowledge of dairy cattle lameness in New Zealand by addressing three overarching goals; to define the extent of lameness on New Zealand dairy farms, to improve the treatment of claw-horn lameness and to prevent new cases of lameness. To define the extent of lameness, the prevalence and duration of lameness were assessed. The prevalence of lameness across 120 dairy farms across eight regions was assessed by trained observers collecting lameness scores of the lactating cattle at two time points over a season. The time to soundness following industry-recommended lameness treatment protocols for claw-horn lameness was also reported from five farms in the Waikato. The median farm level prevalence was 2.8% (interquartile range 1.5 – 4.5%) and median time to soundness 18 (interquartile range 14 - 21) days. Both these outcomes provide confidence that the New Zealand dairy industry are world-leaders when it comes to lameness control, and that appropriate lameness treatment strategies can result in rapid cure rates. However, a large range in farm-level lameness prevalence (0 – 17% on any given day) and differences in cure rates between farms were reported, both suggesting strong farm-level risk factors for lameness. To improve the treatment of lameness, consistent evidence-based advice is required. Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended for painful and inflammatory conditions of dairy cattle. However, the use and advice given for NSAIDs with respect to lame cow treatment is varied. A systematic review of the evidence for NSAID use as part of the treatment of claw-horn lameness was undertaken. Little evidence exists on the benefit of NSAID treatment in isolation at improving lameness cure rates. However, when NSAID are used in conjunction with hoof blocks and early identification of lameness, time to lameness cure can reduce by half. Most farmers (77%) surveyed relied on informal identification of lame cows by farm staff, and few had formal lameness policies implemented on farm. As response to NSAID, and improved lameness cure rates in general, revolve around early identification of lameness on farm, these are areas of improvement that dairy farmers should focus on. Preventative measures for lameness were addressed via three objectives; identifying farm-level risk factors for lameness, investigating a practical pre-calving heifer intervention to reduce lameness incidence and exploring the barriers to lameness control and the motivators for lameness control as reported by farmers. From a questionnaire of 119 of the 120 farmers enrolled into the prevalence study, the use of a concrete stand-off pad during periods of inclement weather was a strong determinate of farm-level lameness, with animals on farms implementing this practice associated with a 1.49 (89% uncertainty interval 1.19 – 1.88) times odds of lameness compared to animals from farms that did not use concrete stand-off pads. Animals from farms that reported peak lameness incidence from January-June or all-year-round, had 0.76 times odds of lameness compared to animals from farms that reported peak lameness incidence from July-December (89% uncertainty interval 0.51 – 0.84). Other risk factors that were associated with greater odds of lameness at the univariable level included split-calving herds compared to 100% spring calving herds, no top gate compared to farms that had and used a top-gate, and no backing gate alarm/hose compared to farms that had an alarm or hose on the backing gate when it moved. Reducing time to first lameness case is one of the keys of lameness control. A randomised clinical interventional study was carried out investigating if a heifer pre-calving intervention involving exercise and time on concrete would result in a reduction in the hazards of lameness. No difference in the time to lameness was noted in heifers exposed to concrete for one hour a day and walked 1km a day on farm tracks for five days a week for five weeks compared to control heifers. The intervention may not have been intense enough to result in the desired response, with evidence for this from the lack of difference in hoof wear between treatment and control heifers. However, as it was possible that a longer or more intense intervention may have resulted in harm, and would have been less practical for a farmer to carry out, it is unlikely that this, or similar interventions will result in meaningful reductions in lameness rates in New Zealand. Finally, the successful implementation of lameness treatment and prevention strategies requires the buy-in of farmers. From the 120 dairy farms enrolled into the prevalence study, 101 responded to a second questionnaire on the barriers, motivators and perceived impacts of lameness. A farmer’s perception of lameness was a poor predictor of true lameness prevalence. The two most important farmer barriers were time and skilled labour, with the most important motivators feeling sorry for lame cows and pride in a healthy herd. Despite the relatively low lameness prevalence, many New Zealand dairy farmers believe lameness is a problem on their farm, and they rank welfare impacts of lameness of high importance.
Lameness in cattle, Diagnosis, Hoofs, Care and hygiene, Dairy cattle, Health, New Zealand, lameness, dairy cattle, prevalence, prevention, treatment, Dean's List of Exceptional Theses