Establishment year productivity, botanical composition and nutritive value of grass/lucerne/plantain dairy pasture mixtures

Abstract

In the context of dairy grazing systems, pasture mixtures including tall fescue, lucerne and plantain have been identified by animal modelling as having potential to both improve milk production and reduce urinary nitrogen excretion. A grazed paddock-scale trial was established in the Waikato in September 2015 to test this in two short-term grazing trials including these species. This paper presents the pasture production, botanical composition and nutritive value data generated from four pasture mixtures sown in spring 2015 and sampled until autumn 2017 (18 months). The pasture mixtures represented a comparison between perennial ryegrass and tall fescue, with and without the herb narrow-leaved plantain. The inclusion of plantain in grass-lucerne mixtures had a positive effect on firstyear herbage dry matter (DM) production, by ~2.6 t DM/ha/year in ryegrass-based pastures and ~1.6 t DM/ ha/year in tall fescue-based pastures. Where plantain was included, the proportion of grass was reduced by more than half from autumn 2016 through to summer 2016-2017, while the proportion of lucerne was reduced to a lesser degree. The proportion of plantain was 35-70% through most of the first year, declining to <20% in the second autumn. Plantain pastures had slightly less crude protein (CP %) in winter, but the inclusion of plantain did not significantly affect digestibility or metabolisable energy in any season. Given the evidence from other studies that plantain can reduce urinary nitrogen concentration in dairy cows, this study indicates that it can be a useful component in mixed pastures from a forage production and nutritive value perspective. Keywords: nitrogen, pasture production, narrowleaved plantain, perennial ryegrass, tall fescue