Effects of ruminal inoculations with tannin-tolerant bacteria on fibre andnitrogen digestibility of lambs fed a high condensed tannin diet

The goal of this study was to evaluate the effects of dosing unadapted lamb s with tannin-tolerant bacteria to improve the digestibility of a high cond ensed tannin (CT) diet. During the initial phase (metabolism study), a diet containing 30% peanut skins was fed to two groups of Suffolk x Finn-Dorset ram lambs that were about three months old and weighed an average of 24.2 +/- 1.4 kg. All animals received 150 ml of a culture (A(600) of 1.0) of a G ram positive rod (a close relative of Eubacterium cellulosolvens) that was able to tolerate 0.5 g/l of purified CT from Desmodium ovalifolium. The con trol group (7 animals) was inoculated with autoclaved bacteria. The treatme nt group (6 animals) was inoculated with actively growing bacteria. Inocula tions were made daily during a three-week period. Dry matter intake (DMI) w as 55.4 and 64.9 g/kg(0.75)/day for the control and treatment group, respec tively, (P = 0.13). Digestibility of DM, crude protein (CP) and neutral det ergent fibre (NDF) was similar between treatments. Crude protein intake (P = 0.10) and CP retention (P = 0.07) were higher for animals inoculated with live bacteria. The CP retention/CP intake ratio was also higher for animal s inoculated with the live bacteria (P = 0.07). To investigate carry-over e ffects on animal performance due to the bacterial inoculations after the me tabolism study, the animals were kept in metabolism cages, but they receive d no supplemental bacteria. During a subsequent two-week period, the animal s continued to receive the high CT diet. Dry matter and CP intake, as well as the feed : gain ratio, were similar between the groups of animals. Final ly, for a second two-week period, the animals were fed a low CT (normal) di et without peanut skins. Dry matter intake was 92.9 and 88.6 g/kg(0.75)/day for the control and treatment groups, respectively (P = 0.14). Crude prote in intake and feed : gain ratio were similar between the two groups of anim als. (C) 1999 Elsevier Science B.V. All rights reserved.