Dry matter (DM) concentration of maize silage is directly related to maturity of the crop at harvest and widely reported to be positively correlated with total forage DM intake. The objective of this experiment was to investigate these effects using a late maturing beef genotype and a contemporary forage maize variety.

Forage maize (variety Hudson) was harvested at four different stages of maturity during September and October 1996. Each stage of maturity was ensiled in a separate clamp with no additive. Resultant silage corrected dry matter contents were 247 (L), 305 (M/L), 331(M/H) and 388 (H)g/kgFW, respectively. Each diet was formulated to be isonitrogenous with fishmeal fed twice daily on top of the silage. Silage was offered ad libitum to 32 growing Simmental X Friesian heifers (mean initial weight 217kg), housed in individual pens in an open-sided Dutch barn and bedded on wheat straw. Eight animals were allocated to each treatment, in a completely randomised design with pre-treatment intake (non-experimental maize silage) used as a covariate in the statistical analysis.