Influence of Drinking Water with Quebracho Tannin on Intake of Endophyte-Infected Tall Rescue by Cattle

Endophyte-infected tall fescue (TF) contains alkaloids that can adversely affect the productivity and health of livestock. These effects are exacerbated when livestock forage on TF grown in monoculture, but they are mitigated when livestock forage on pastures that contain TF in mixture with tannin-containing plants, evidently because tannins bind to the steroidal and protein-like alkaloids found in TF. Cattle and sheep will drink water that contains up to 20 g/L condensed tannins. We hypothesized that cattle (n = 8) offered water containing quebracho tannins (10 g/L) would eat more TF than cattle (n = 8) offered plain water. During the trial, cattle were offered 9 kg/(animal * d) of freshly harvested TF. Cattle drank less water with than without tannins (17.7 kg/d vs. 24.6 kg/d; P \u3c 0.005), and they tended to eat less TF (4.3 kg/d vs. 5.1 kg/d; P = 0.10). No differences in weight change occurred during the trial (P = 0.83) or between groups (P = 0.70). The negative impacts of tannins on water intake likely depressed intake of TF, but the lower intakes of tannin water and TF did not adversely affect BW. On the one hand, water restriction and dehydration reduce food intake and any agent that limits intake of water will adversely affect food intake and animal performance. On the other hand, while cattle with fresh water maintained BW during the trial, so did cattle with tannin water, which suggests the tannin may have benefited the cattle fed a diet of orchard grass hay and TF. Further studies are required to assess the role of tannins in water on both the intake and performance of livestock eating TF