As loss of weight is almost the only sign of ovine PTBC, we compared the digestibility of paratuberculous sheep to that of animals affected by respiratory wasting diseases, as a means to check the importance of malabsorpiton in the pathogenesis of PTBC. The study was a conventional digestibility trial in which a total of 18 ewes were used in 3 series of 6. The digestiblity was assessed for 9-10 days, in a daily and individual basis, as the percentage of dry matter, organic matter and crude protein consumed that was not excreted by feces. The actual status of each animal was tested post-mortem on the basis of gross and microscopic lesions. Finally, only 3 animals with extensive lesions of PTBC were retained. The respiratory group was dividied in 3 animals with maedi and 3 with pulmonary adenomatosis. This, analysis of the results were carried out for 4 groups instead of 3, with only 15 ewes. The only group that gained weight throughout the experiment was the paratuberculosis one, which was the only one that consumed all the food offered. The highest loss of weight was observed in the control group, which only ate about 70% of its food. Regarding the digestibility, no significant differences between groups were found for any of the variables, being the results ranked from the best ones of the paratuberculosis group to the worst ones of the maedi group. Although a number of difficulties affected the study, our results indicate that the mere presence of extensive lesions does not interfere with digestive function of sheep. This could be in agreement with observations on the ability of PTBC diseased animals to improve their condition for short periods, and with the known lack of correlation between severity of pathological changes and clinical signs. Thus, the results of our trial, suggesting that intestinal malabsorption could not place a significant role in ovine paratuberculosis, further support the likely hypothesis of macrophage release of TNF-a being the mechanism of wasting in PTBC.