VALUATING THE POTENTIAL OF TRIDAX PROCUMBENS FOR LIVESTOCK FEED

MORPHOLOGICAL STAGE OF DEVELOPMENT AND CHEMICAL COMPOSITION

Résumé

A quantitative method of specifying the morphological stage of development in Tridax procumbens was used for evaluating the chemi­cal _composition of the plant at specified cano­py ages. An eight stage classification system was defined and assigned numerical values from 1 to 8 in a sequential order of increasing maturity. The mean stage of total herbage (MSW) at a specified age of canopy was calcu­lated as the average of the individual stages present and weighted for the dry weight in each stage. For the individual morphological stages present in a herbage samples, quality components measured by_. leaf percentage, crude protein (CP), in vitro true digestibility (IVTD), progressively decreased with maturi­ty. From the vegetative to the mature seed stage, decreases were from 90% to 26% for the leaf proportion; 28% to 14% for CP; and from 82% to 53% for IVTD. Corresponding increases in fibre composition were from 26% to 59% for the total cell wall or neutral deter­gent fibre (NDF); 22% to 40% for ligno-cellu­lose or acid detergent fibre (ADF); and from 25% to 9% _ilignin^. . Older canopies reached siginificantly higher mean stage (MSW) values than younger canopies. Associated with these were lower percentage, CP, and IVTD; higher NDF; ADF, and lignin at higher MSW values. The implications of these findings are fully discussed