Use of complex number in the analysis of increase in dry matter indigestibility with growth of forages

This study was conducted to give a trigonometric representation, using comp lex numbers and plane, of the increase in dry matter indigestibility [IDMI] with growth of forages. The following results were obtained. Divisional ca lculations between two coordinates of dry matter indigestibility [DMI] expr essed using complex numbers were related Go the subtraction theorem of tang ent. This relation might give some information on DMI changes, namely IDMI, the geometric mean of DMI [GMDMI] and relative IDMI (=IDMI/GMDMI). Changes in dry weight and indigestible dry weight with forage growth were visualiz ed by the geometric representation. Therefore, there were four information on IDMI given by the trigonometric representation of DMI on the complex pla ne. It was suggested that the complex representation of DMI of forages deri ved, from the subtraction theorem of tangent, some information opt IDMI wit h forage growth.