TANNIN AND IN-VITRO DIGESTIBILITY OF TROPICAL BROWSE - PREDICTIVE EQUATIONS

Summative equations to predict digestibility of tropical browse specie s for cattle were tested by comparison to in vitro digestibility. Four equations were used for the comparison: first the 2 Van Soest equatio ns, 1 using sulfuric acid lignin and the other using permanganate lign in, neither of which have a correction for tannins. And second, the 2 Horvath equations, each using 1 of the 2 above mentioned lignin values and both include a value for tannin content. The Van Soest equation u sing permanganate lignin and the Horvath equation using sulfuric acid lignin predicted the in vitro digestibilies of the leaf species quite well (r = 0.89 for both). The same Horvath equation predicted the dige stibility of the high tannin species better than the Van Soest equatio n (r = 0.93 versus 0.84). For initial evaluation and ranking of browse species suitable for future research efforts, either equation suitabl e.