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It remains a challenge for the role of the dairy veterinarian to move beyond that traditionally held. In larger herds with a high reproductive workload, we are at great risk of becoming specialist technicians. Instead we seek greater involvement, to deliver comprehensive services and to be recognised for them, personally and financially. Given the frequency of our visits, knowledge and analytical skills we are in a unique position to provide inputs that complement advice given by other consultants. Failure to do so has economic consequences for both veterinarian and dairyman. The opportunity for and value of inputs will differ for every client, and we need to remain cognizant of their motivation. This review article shares perspectives, opportunities and tools that might enable moving beyond the traditional role. It starts with a review of available research describing the dynamic between dairyman and veterinarian and how this might impact an animal health production management programme. A description of the experiences of others follows, interspersed by the personal experiences of the author, working with large total mixed ration-fed herds in the United States of America. The following attributes and roles can be associated with a significant economic impact: gatekeeper; conduit; executor; verifier; monitor; facilitator and mediator; trainer, motivator and coach; applied nutritionist; technologist; champion of animal welfare, food safety and judicious antibiotic use; and confidant. Each is elucidated and described in context, revealing a need for continuing education. The nature of the relationship between veterinarian and client will determine the opportunity for and value of each. The veterinarian is in a unique position to become an integral part of the management team and to be fairly compensated as such. The onus rests on the veterinarian to broaden his/her knowledge and skills and to demonstrate their value.

Serum samples collected from feral swine (Sus scrofa) throughout Florida (USA) from 1980 to 1989 were tested for antibodies to pseudorabies virus (PRV) by the serum neutralization test, the latex agglutination test, or by the enzyme-linked immunosorbent assay. Seropositive swine were detected at 11 of 13 sites with a composite seroprevalence of 34.8% (579 of 1,662 samples; range = 5.9% to 58.2%) for sites with seropositive swine. Data on age and sex of the swine were available from three sites. Seroprevalence in males and females did not differ significantly (P = 0.62 for the combined data). Seroprevalence in adult (> or = 8 mo) and juvenile swine (< 8 mo) was significantly different at all sites (P < 0.05 for the combined data). From these data, PRV infections appear to occur widely in populations of Florida feral swine and may seriously undermine efforts to eradicate this virus from the domestic swine population of the USA.

Serum samples collected from feral swine (Sus scrofa) throughout Florida (USA) from 1974 to 1989 were tested for antibodies to Brucella sp. by the card test, the standard tube test, the rivanol test or the complement fixation test. Seropositive swine were detected at six of 18 sites with a composite prevalence of 23.4% (238 of 1,015 samples; range = 5.5% to 33.3%) for sites with seropositive swine. At one site for which age and sex data were available there was no significant difference (P = 0.50) in seroprevalence between males and females. Antibody prevalence in adult (> or = 8 mo) and juvenile swine (< 8 mo), however, was significantly different (P < 0.05). Based on these data, Brucella sp. infections are limited only to certain populations of feral swine. To avoid the spread of Brucella sp. organisms, however, relocation of feral swine is not recommended.

After confirming that long-term serum storage (frozen at -20 C for greater than 3 mo) causes optical density to drift upward, several modifications of an enzyme-linked immunosorbent assay (ELISA) protocol were evaluated to identify a protocol that would reduce background in porcine sera tested for trichinellosis. Modifications evaluated included blocking the antigen-coated ELISA plate with sample diluent containing 10% bovine serum albumin (BSA) or 10% nonfat milk powder (bovine lacto transfer optimizer or BLOTTO), diluting sera in sample diluent containing 10% BSA or 10% BLOTTO, and preincubating samples in sample diluent containing 10% BSA or 10% BLOTTO. Overnight preincubation (approximately 12 hr at 2 C) of fresh sera diluted (1:10) in sample diluent containing 10% BLOTTO significantly reduced background and improved the detection of experimentally infected pigs by enhancing positive-negative discrimination. When testing stored sera, the modified protocol effectively reduced the effect of storage and the kit revealed specificity of 98.4%; there was no loss in sensitivity. The effect of long-term storage at -20 C must therefore be considered when testing swine sera for trichinellosis by ELISA and possibly also when conducting other immunoglobulin assays. The modification described here may prove useful if there is no alternative to using serum stored for greater than 3 mo at -20 C.

Following the use of diflubenzuron controlled-release insecticide boluses in a dairy herd, there was a concern that post-calving cows were testing positive on a milk antibiotic residue test for more milkings than they had prior to the use of diflubenzuron. A field trial was conducted to examine for possible effects of diflubenzuron milk residues on the milk antibiotic residue test, Delvotest-P. Data of 24 cows in the treatment group and 29 cows in the control group were analyzed. There was no significant difference in the number of milkings after calving in which the milk tested positive on the milk antibiotic residue test between the treatment (2.75 +/- .94) and control (2.97 +/- 1.05) groups when cows in all lactations were analyzed or when analyzed by lactation (1, 2, and greater than or equal to 3). It was concluded that the use of diflubenzuron boluses had no effect on the milk antibiotic residue test.