South African Journal of Animal Science
On-line version ISSN 2221-4062
Print version ISSN 0375-1589
Digestion trials using sheep and voluntary feed intake (VFI) trials using long yearling heifers in Calan gates were conducted in the spring, summer and autumn over 5 years. These data and the chemical composition of the herbage were regressed on DMD and VFI. Excluding the mineral fractions, only three of the chemical components of the herbage emerged as important, namely, the DM content of the herbage as fed, accounting for 32% of the variance in DMD, the NPN content of the herbage accounting for only 12.2% of the variance and the ash content of the herbage accounting for 15.9% of the variance in digestibility. Of the macro-mineral components, Ca, Mg and P tended to be positively associated with DMD, while Na and K were significantly related to DMD. NDF was positively correlated to VFI, accounting for 37% of the variability in intake, while non-protein nitrogen was negatively correlated to VFI, although it did not account for much of the variability (11%) in VFI. Ca was also positively correlated to VFI, also accounting for very little of the variation in VFI (11.7%). Herbage Mg had a positive influence on VFI, accounting for 24% of the variation in VFI. Both DMD and VFI were highly negatively influenced by the moisture content of the herbage.
Keywords : Pennisetum clandestinum; DMD; VFI; chemical composition.