| Abstract: | A method for the evaluation of Mycobacterium bovis purified protein derivative (PPD) tuberculin in experimentally infected cattle is presented. The development of skin test responses in M bovis-infected cattle was determined for International Standard PPD-S, M bovis PPD-2, and M bovis PPD-5 at 24, 48, and 72 hours. Significantly larger reactions (dermal thickness) were observed at 48 and 72 hours than at 24 hours (P = 0.001). Statistically significant differences were not detected in the responses obtained with M bovis PPD-2, M bovis PPD-5, and International Standard PPD-S if comparisons were made at approximately the same concentrations in M bovis-infected cattle (P greater than 0.25). In Mycobacterium avium-infected cattle, M bovis PPD-2 produced skin test responses that were significantly smaller than responses obtained using M avium PPD-2 (P = 0.001). Significant variation was not observed in the PPD-S responses in 2 groups of M bovis-infected cattle (P greater than 0.1). |
