Development of methods to evaluate hoof conformation and lameness in New Zealand dairy goats and the effects of trimming regimes on goat hoof health : a thesis presented in complete fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University (Manawatu) New Zealand
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2020
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Massey University
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Abstract
Lameness is a debilitating and painful condition. It is considered a major welfare and economic issue in the dairy industry, due to its high prevalence and associated production losses, and the serious impact it has on individual animals. One major risk factor for lameness is hoof overgrowth and consequently poor hoof conformation. Dairy goats in New Zealand are largely housed indoors; such environments offer limited opportunity for natural hoof wear, therefore hoof overgrowth is likely to be common. However, there are few data in New Zealand evaluating hoof conformation, lameness, or how we can best maintain a normally structured hoof and minimise lameness in commercially housed dairy goats.
The overarching aim of this thesis was to examine the hoof conformation and gait of New Zealand dairy goats and to evaluate how these factors are impacted by hoof trimming. Specifically, I aimed to develop and validate a hoof conformation assessment for use in dairy goats, and to develop a reliable gait scoring system that would allow detection of an uneven gait as a potential precursor to clinical lameness. Furthermore, I aimed to use these methods to evaluate the immediate impacts of hoof trimming and the longer-term impacts of early life hoof trimming and subsequent trimming frequency on anatomical (e.g., hoof conformation, joint positions, hoof growth) and behavioural (e.g., lying behaviour, gait) variables.
The hoof conformation assessment was determined to be reliable following considerable training of observers; both the objective measures and subjective scores could be used to accurately assess aspects of hoof conformation from photographs. As the subjective scores are less time-consuming and do not require technical equipment, I suggest they should be trialed for on-farm use.
A reliable 5-point gait scoring system was developed in a controlled setting at the AgResearch Goat Research Facility. It included an “uneven gait” category, allowing identification of goats which may be predisposed to developing clinical lameness. However, whether it is feasible to detect an uneven gait from live observations on commercial farms is still to be determined.
In an observational study conducted on 16 farms (n = 1099 goats; mean ± SD: 64 ± 9 goats/farm), goats that had not been trimmed prior to first mating (8.0 ± 0.70 months) had greater odds of poor hind hoof conformation at that time compared with goats on farms that had already trimmed prior to mating. In the longer term, goats on farms that had not trimmed before first kidding (14.8 ± 0.86 months) had greater odds of having dipped heels on the hind hooves at the end of second lactation (34.1 ± 0.90 months). In contrast, in a controlled experimental study conducted on one farm (n = 80 goats), only minor effects of early life trimming (before first kidding) on hoof conformation were found, and these were not consistent at assessments completed at the end of the first (13 months) and second lactations (25 months). In the experimental study, as poor conformation was observed in both the early and late trimmed treatments, it suggests that the subsequent hoof trimming (3 times per year) was not frequent enough to prevent overgrowth; the early life trimming treatment was not effective at this trimming frequency. In the observational study, trimming frequency following first kidding had no observable effects on hoof conformation. However, differences in the housing environment and management may be strongly impacting hoof conformation across the 16 farms.
In the short term, immediate beneficial effects of hoof trimming were observed in the experimental study, with aspects of hoof conformation and joint positions restored to more anatomically correct shapes and positions. There was also some evidence of a transient effect of trimming on lying behaviour, with lying time increasing the day after hoof trimming at 3 out of 4 assessments over the first two years of life. An increase in lying time may be indicative of a pain response. However, daily lying behaviour was highly variable so should be interpreted with caution.
High proportions of dipped heels, misshaped claws and splayed claws, particularly in the hind hooves, were recorded on 16 farms in the observational study and before trimming in the goats on the experimental study. Interestingly, on the latter farm, the prevalence of clinical lameness (scored from videos) in the same goats was lower than expected over the 2-year study period, though prevalence of an impaired gait (either uneven gait or clinical lameness) peaked after both kidding events. In addition, the rate of hoof growth changed across the goats’ first two years of life, slowing when the goats were in kid.
Overall, my findings suggest that the trimming regimes evaluated in these studies were not adequate to prevent poor hoof conformation in goats housed in indoor environments that do not promote hoof wear. In order to achieve good conformation and long-term hoof health, dairy goat hoof management strategies should include consideration of the timing of first hoof trimming and subsequent trimming frequency, as well as providing an environment that promotes hoof wear.
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Two papers in the Proceedings of the New Zealand Society of Animal Production were removed from Appendix Four Conference Proceedings, in accordance with publisher policy. The article in Appendix Three is republished under a CC BY-NC-ND license, and linked to the original article: https://doi.org/10.3168/jds.2019-16264
Keywords
Goats, Health, New Zealand, Hoofs, Care and hygiene