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The experimental challenge with M. ptb produced subclinical Johne's disease in the majority of deer, but did not cause any clinical disease. The number and severity of gross and microscopic lesions was significantly reduced in the COM compared with Control and EXP groups; vaccination of the EXP group did not appear to give significant protection. Deer vaccinated with the commercial vaccine are likely to give a false-positive reaction to the MCT but should have an avian reaction to the CCT, if it is carried out >12 months after vaccination. Most of the deer vaccinated with the commercial vaccine produced significant levels of antibodies against both M. ptb and M. bovis, which interfered with ancillary Tb tests. If this vaccine or similar oil-based vaccines are used on deer farms in the future, it may be advisable to only vaccinate animals destined for slaughter, that would not need to be Tb-tested, but would be 'works-monitored' for evidence of Tb instead.

This study demonstrated a high rate of transmission of M. ptb from dam to fetus in red deer, and a potential risk of transmission to fawns suckling from mothers that are subclinically affected with Johne's disease.

The Lucerne for Lambs Sustainable Farming Fund project used on-farm data and whole-farm modelling to help farmers understand the impact of increasing the amount of grazing dryland lucerne on Central Otago farms. On-farm results from 2 years showed that spring stocking rate on lucerne-based pasture averaged 10 ewes and their lambs per hectare compared with 3 ewes and their lambs on dryland grass-based pasture. Lamb growth rate was approximately 50 g/day higher on lucerne-based pastures, resulting in a total lamb production of 358 kg liveweight/ha at weaning compared with 108 kg liveweight/ha on grass-based pastures. Whole-farm modelling showed that increased profitability could be achieved by the addition of significant areas of grazing lucerne. Profitability increased by $119/ha on a 5000 ha traditional merino property. Profitability of a 522 ha partially irrigated valley floor property running crossbred ewes was increased by $249/ha. Using lucerne for spring grazing also reduced the impacts of both winter and summer droughts in the variable conditions of Central Otago. Keywords: dryland, lamb growth, lucerne, modelling, profitability, stocking rate, whole farm systems.