Generation of EST and cDNA Microarray Resources for the Study of Bovine Immunobiology*

Differential gene expression segregates cattle confirmed positive for bovine tuberculosis from antemortem tuberculosis test-false positive cattle originating from herds free of bovine tuberculosis

Antemortem tests for bovine tuberculosis (bTB) currently used in the US measure cell-mediated immune responses against Mycobacterium bovis. Postmortem tests for bTB rely on observation of gross and histologic lesions of bTB, followed by bacterial isolation or molecular diagnostics. Cumulative data from the state of Michigan indicates that 98 to 99% of cattle that react positively in antemortem tests are not confirmed positive for bTB at postmortem examination. Understanding the fundamental differences in gene regulation between antemortem test-false positive cattle and cattle that have bTB may allow identification of molecular markers that can be exploited to better separate infected from noninfected cattle. An immunospecific cDNA microarray was used to identify altered gene expression (P ≤ 0.01) of 122 gene features between antemortem test-false positive cattle and bTB-infected cattle following a 4-hour stimulation of whole blood with tuberculin. Further analysis using quantitative real-time PCR assays validated altered expression of 8 genes that had differential power (adj  P ≤ 0.05) to segregate cattle confirmed positive for bovine tuberculosis from antemortem tuberculosis test-false positive cattle originating from herds free of bovine tuberculosis.

Methodologies by which to study and evaluate welfare issues facing livestock systems of production

The viability of livestock farming requires practices that are not only productive and profitable but fit with society’s expectations on ethical dimensions such as animal welfare. Scientific methodologies for the evaluation of welfare issues and welfare status that reflect the diversity of ethical views about animal welfare are required. Unfortunately, there is no comprehensive, fully validated system for evaluating the welfare standards of livestock in New Zealand, Australia or elsewhere. Development of appropriate welfare assessment methodologies that are credible to all stakeholders will require a better understanding of: (i) changes in physical health and functioning that correspond with different levels of welfare; (ii) the capacities of livestock to experience negative and positive mental states and associated levels of welfare; (iii) the ways that separate measures and welfare attributes can be weighted and integrated to give an overall index of welfare; and (iv) validated, practical measurement tools for use in the production environment. It is argued that an animal-centric approach is required to achieve these aims, particularly the use of measures that reflect not just the responses of animals, but their perceptions as well. Further, there is a need to extend the perceptions approach from the current focus on measurement of resources that animals need (or need to avoid), to measurement of perceptions about health states. Existing and novel techniques based on behavioural economics offer the most promise for achieving these aims. A similar animal-centric, perception approach offers a novel method for developing an overall index of welfare that allows integration of welfare status across welfare domains and reflects the animals’ views (rather than human judgement, as at present). Conventional wisdom has it that animal welfare is high in pastoral production systems typical for Australasia. The reality of this perception awaits the further development and application of comprehensive practical, validated welfare monitoring methodologies.