Effect of dental correction on feed digestibility in horses

To test the hypothesis that routine dental correction (removal only of sharp hooks and points from molars and premolars) would improve digestion of a hay/grain ration whereas performance 'floats' (rounding and smoothing of the dental arcades) would adversely affect digestion, 8 mature horses free from dental correction for over a year were used. Five-day digestion trials were conducted before and 2 and 4 weeks after correction in all horses. Although all horses had sharp points and minor premolar hooks, none had severe dental abnormalities. There were no significant differences found in apparent digestion of dry matter, crude protein, neutral detergent fibre or acid detergent fibre relative to precorrection data or controls (uncorrected horses on same digestion trial). Apparent digestibility of crude protein and fibre, however, was reduced if the occlusal angle of premolar 307 was greater than 80 degrees relative to the vertical axis (flattened). It should be recommended that regular dental correction be continued. However, if only small points and hooks are present, correction will not significantly improve digestion. Performance floating does not adversely affect digestion 2-4 weeks after the procedure is performed. Alterations in molar occlusal surface angle may affect digestibility of protein and fibre.     

A comparison of the efficacy of two commercial Aujeszky's disease vaccines with glycoprotein-I deletion in pigs

Two commercial Aujeszky's disease vaccines, a modified killed vaccine and a sub-unit vaccine, both carrying a deletion of glycoprotein-I, were evaluated in pigs. Each vaccine was administered to two groups of four pigs, twice at 4-week intervals, with two pigs held as unvaccinated controls. All pigs were challenged with a New Zealand field isolate of Aujeszky's disease virus 3 weeks after the second vaccination. The results indicate that the sub-unit vaccine was able to protect pigs against clinical Aujeszky's disease much better than the pigs vaccinated with the modified killed vaccine when challenged with a virulent virus. However, the amount and the duration of virulent virus excretion following challenge was greater with the sub-unit vaccine than the modified killed vaccine. Pigs vaccinated with the sub-unit vaccine were shown to be latently infected following challenge. Latent infection was demonstrated by excretion of Aujeszky's disease virus from the nasal cavity after dexamethasone treatment and seroconversion of a sentinel in contact pigs to Aujeszky's disease virus.     

gIII antibody responses in pigs following vaccination and challenge to Aujeszky's disease.

Serological responses to a genetically engineered Aujeszky's disease "marker" vaccine (dl gIII + dl tk) were monitored using a blocking-ELISA (B-ELISA), a serum neutralisation test (SNT) and an indirect ELISA (I-ELISA). The B-ELISA is capable of differentiating pigs vaccinated with the above vaccine from natural infection. The SNT and the I-ELISA indicated that the pigs responded to vaccination and challenge. All three tests showed that the controls and the in-contact pigs always reacted negative for antibodies. The B-ELISA was able to detect pigs challenged with a field isolate 24 days post-challenge. These pigs remained positive until 110 days post-challenge when last tested. These findings indicate that the B-ELISA could be used successfully with this vaccine in a control eradication programme. This trial also shows that the vaccine virus did not spread to the in-contact pigs and also the vaccinated and challenged pigs did not transmit the disease to other susceptible pigs when they were introduced 14 days after challenge.