193 Tannins as antinutritive chemicals in red cedar

Abstract

Abstract Studies using goats to control red cedar (Juniperus virginiana) have shown that goats more readily consume red cedar at some locations while in other locations, they consume relatively little, but consume more during the winter. It was hypothesized that differences in red cedar intake may be caused by tannins acting as an antinutritive chemical. The purpose of this study was to characterize the levels and types of tannins in red cedar from different locations and seasons of the year. Thirty-seven samples of red cedar needles were obtained from four locations (LOC; Langston, OK; Midwest City, OK; Mannford, OK; Neosho, MO) at monthly intervals (SEA) over a 1-yr period. Needles were manually stripped from branches at approximately 1.5 m high from at least 25 plants at each location. Samples were refrigerated until analyzed for extractable condensed tannin (ECT) and total tannin (TOT) by procedure of Terrill et al. (1992). Data were analyzed by SAS GLM with main effects of LOC and SEA. ECT was significantly lower for Neosho (1.53%) than for Mannford (2.69%), Midwest City (2.79%), and Langston (2.37%), which were similar. ECT was lowest for Summer (1.76%), similar to Fall (1.85%) and both were significantly lower than for Winter (3.32%) and Spring (2.39%). TOT followed a similar pattern being highly correlated to ECT (R = 0.955; P < 0.001) and was significantly lower for Neosho (2.61%) than for Langston (3.79%), Mannford (3.81%) or OKC (4.15%). Total tannins were significantly higher in the winter (4.71%) than for the other seasons (Spring 3.64, Fall, 3.18% and Summer 2.87%). Tannins were lowest for Neosho where goats browsed red cedar most aggressively, killing >85% of the trees whereas goats killed <10% cedars at other locations. Tannins may be a significant antinutritive factor in red cedar, affecting consumption and degree of control