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.