FORMATION OF INDIGESTIBLE MATERIALS AND INCREASE IN DRY-MATTER INDIGESTIBILITY IN THE GROWTH OF 2 TROPICAL FORAGES

This study was conducted to analyze the formation of indigestible mate rials [equation (A)] and the increase in dry matter indigestibility [e quation (B)] in the growth of Rhodes grass (Rg) and Greenleaf desmodiu m (Gd). 1/W . dl/dt = C/W . (1/C . dL/dt) . dl/dL, (A) where (1/W) . ( dl/dt) = formation rate of I (indigestible materials) per unit W (fora ge dry weight) [FRI], C/W = the ratio of C (cell wall constituents) to W [CWC ratio], (1/C) . (dL/dt) = formation rate of L (lignin) per uni t C [Specific FRL], dl/dL = formation of I per unit increase in L [FIL ]. I-2/W-2 - I-1/W-1 = (1 - W-1/W-2) . ((FRI) over bar/<(RGR(w))over b ar> - I-1/W-1), (B) where (I-2/W-2-I-1/W-1) = increases in dry matter indigestibility [IDMI], W-1 not equal W-2, (1-W-1/W-2) = forage growth index [FG index], <(FRG(w))over bar> = mean relative growth rate of f orage, ((FRI) over bar/<(RGR(w))over bar> - I-1/W-1) = index for dry m atter partition into indigestible materials [DMP index]. Each attribut e was given a bar on it to show mean value over the interval t(1) to t (2). The results obtained were as follows. 1. (FRI) over bar was highe r in Rg than in Gd and this was due to both higher <(CWC ratio)over ba r> and higher (FIL) over bar in Rg. 2. IDMI was larger in Rg compared to Gd, which was due to higher DMP index with some contribution by FG index. It was suggested that this method was available for a macro ana lysis of the change in dry matter indigestibility occurring in the gro wth of forages.