Milk samples from dairy cows provide a ready source of material for measuring antibody reactions to antigens. (1). The test-and-slaughter programs have been based on screening of animals using the tuberculin pores and skin test, which measures delayed hypersensitivity reactions to purified protein derivative (PPD) prepared from or which, in some countries, compares PPDs prepared from and infections in animals which have not responded in pores and skin checks HCl salt (4, 5, 6), particularly those which possess severe pathology and are more likely to shed in milk samples provides advantages in that milk samples are routinely collected for dairy herd improvement HCl salt screening and can become pooled from groups of animals. In regions of New Zealand which are considered free of bovine TB, the interval between tuberculin pores and skin checks has been extended to 3 years. The use of an inexpensive testing assay such as a pooled milk serological test for bovine TB in the interval between skin checks might provide added assurance the herds remain free of TB. An economic analysis of the control strategies for bovine TB monitoring indicated that enzyme-linked immunosorbent assay (ELISA) screening of bulk milk samples may be a cost-effective strategy if the screening became feasible (7). Motivating results for the detection of antibodies to in individual and bulk milk samples were recently reported (6, 8), and the detection of antibodies in bulk milk samples has been used in control programs for the diagnosis of brucellosis, enzootic bovine leukosis, and Johne’s disease in cattle (9C11). However, one of the concerns with the use of serological tests for the detection of infection in cattle has been the variation in the sensitivities of tests when applied to sera from = 184), 69% from Ireland (= 130), 46% from the United States (= 122), and 40% from New Zealand (= 42). These variations may have resulted from cattle being at different stages of infection or from differences in the antigenicities or virulence of the strains. In addition, there might have been differences in how the diagnostic tests were applied; whether blood samples for serology were collected following tuberculin skin testing, possibly boosting antibody responses or blood sample collection for serology, was not related to the application of the skin test. The sensitivities of the serological tests appeared to be lower in countries where control of the disease has been more successful, such as the United States and New Zealand, than in countries with less successful control, such as Ireland and Great Britain. As of June 2012, only 70 cattle and farmed deer herds in New Zealand were classified as being infected with bovine TB (12). The current study was undertaken to determine whether a milk serological test can be a valuable test in a country which has a low incidence of bovine TB in domestic animals and also in which infected animals are generally detected at an early stage of the disease. MATERIALS AND METHODS Samples from infection. The majority of the samples in the 2010-2011 milking season (= 72) were collected in the period HCl salt of 10 to 30 days after injection of the skin test reagents when blood samples were collected for the whole-blood gamma interferon (IFN-) test (Bovigam test; Prionics AG, Schlieren, Switzerland), while samples in the 2011-2012 milking season (= 188) were predominantly collected at the time of reading of the skin test, as this was considered more time efficient. A total of 135 animal necropsies were performed in accordance with the decision to slaughter TB reactor cattle based on the HCl salt disease history of the herd and results of the whole-blood IFN- test using previously described cutoff values (3). Forty-four cows were classified as infected with was cultured from their pooled lymph nodes. The definition of infection was based on the culture of by Bactec and confirmation by Accuprobe or typical tuberculous-like lesions with histopathological confirmation. Confirmation by histopathology was used only when more than three animals MCF2 from a herd had tuberculous-like lesions on one occasion, and samples from three animals with lesions had been collected for culture of infected to allow comparisons between antibody responses in milk and serum samples from HCl salt the same animals gathered on a single day time. The 216 pets which were tuberculin reactors but weren’t categorized as contaminated with were.