The prediction of grass silage intake by beef cattle receiving barley-based supplements

Abstract

Data on the intake by beef cattle of 11 silages either unsupplemented or supplemented with barley-based concentrates were provided from six studies carried out at the Institute. An empirical model was developed from these data which described an exponential decrease in silage intake as concentrate intake was increased, with y-axis intercepts corresponding to unsupplemented silage intakes and a common x-axis intercept of 73.2 (S.E.=2.00) g/kg W 0.75 corresponding to concentrate intake when offered as a sole feed. The model curvature ( r parameter) was also shown to be constant for all silages (1.025 (S.E.=0.0038)). When the model was validated against external data (11 published studies), the relationship between actual and predicted silage DMI gave an R 2 of 0.89 with an intercept and slope not significantly different from 0 and 1, respectively. Seventy-six percent of silage DMIs predicted using the developed model were within 0.5 kg DM of the observed intakes in the validation data. The developed model showed an improvement over a previously published model, as indicated by a significant reduction in the mean squared prediction error.