The effect of plant structure on the acceptability of different grass species to cattle

Abstract

The changes in the acceptability to cattle of nine indigenous grass species over the grazing season were related to nine characteristics of the species. Acceptability was positively related to tuft diameter, leaf percentage, leaf table height and leaf crude protein, but was negatively related to stemminess. Species of preferred acceptability were leafy and non‐stemmy, with a high leaf table and had leaves of low tensile strength containing high crude protein. Avoided species were generally stemmy and had leaves containing low crude protein. Acceptability was largely determined by plant structure but was also influenced by leaf crude protein and tensile strength. Plant structure appears to modify acceptability by altering the nutritive value of the plant to the animal through its effect on intake rates. It is suggested that stemminess may increase resistance to herbivory by limiting the degree of tissue loss.

Die verandering in die aanvaarbaarheid van nege inheemse grasspesies vir beeste is gedurende die groeiseisoen met nege verskillende eienskappe van die grasspesies vergelyk. Daar is gevind dat ‘n positiewe verwantskap tussen die aanvaarbaarheid en pol‐deursnee, blaartafelhoogte, blaarpersentasie en blaar ru‐protefen bestaan, maar ‘n negatiewe ooreenkoms met stokkerigheid toon. Voorkeurspesies was blaarryk, nie stokkerig nie, het ‘n hoe blaar ru‐proteïen‐inhoud maar lae blaar breekkrag gehad. Aanvaarbaarheid is grootliks deur plant‐struktuur bepaal, maar is ook deur blaar ru‐proteïen en blaar breekkrag beinvloed. Klaarblyklik bei'nvloed die plantstruktuur aanvaarbaarheid, deurdat dit die tempo van inname negatief bei'nvloed, wat die voedingswaarde van die plant vir die dier benader.

Additional index words:

• Leaf accessibility
• protein
• tensile strength