The effect of condensed tannins on immune response in beef cattle

Selection for nutrients alone is likely insufficient to account for highly variable ruminant diets. Selection for plant secondary compounds may occur to rectify deficiencies and even self-medicate. This study investigates the relationship between condensed tannins and immune response. Twenty angus heifers were randomly assigned treatment groups. All heifers were offered 4% body weight in feed, daily. Treatment feed contained 6% grape/blueberry pomace as a source of tannins. Intake was measured for the duration of the trial (21 days). On day 15, heifers were vaccinated with modified-live IBR/BVD vaccine. Body temperatures and blood (erythrocytes, leukocytes, and immunoglobulins) were collected pre/post-inoculation. Treatment group intake was higher post-inoculation (P ≤ 0.05). Blood data and average daily gain were similar among treatments. A significant, though apparently artifactual, group-day interaction was observed for body temperature. While a relationship between condensed tannins and immune cells/antibody production was not established, intake results suggest tannins may still be relevant.