Does pasture diversity enhance growth and nutritive characteristics of dairy pastures in south-eastern Australia?

Abstract

Context Australia’s dairy production relies predominantly on grazed rainfed perennial ryegrass pastures. Multi-species pastures, including grasses, legumes, and herbs, have potential to improve pasture dry-matter (DM) production and nutritional value, relative to perennial ryegrass pastures. However, there are limited data on their performance under Australian conditions. Aims To assess pasture yield and nutritive characteristics of multi-species pastures compared with perennial ryegrass pastures on Victorian dairy farms. Methods A paired paddock approach over 18–24 months (June 2022 to June 2024) across 10 commercial dairy farms was used. Seasonal DM production and nutritive characteristics were assessed, and pasture type × season interactions were tested. Key results Significant pasture type effects were observed at six of the nine farms, either as main effects or through interactions with season and/or year. At Barongarook West, multi-species pastures outperformed perennial ryegrass pastures notably in summer 2023/24 (3.52 vs 1.76 Mg DM ha−1). At Tallandoon and Towong Upper, multi-species pastures produced biomass in autumn 2024 (2.86 and 0.23 Mg DM ha−1 respectively), whereas perennial ryegrass did not grow, demonstrating better production under challenging conditions. Where conditions were favourable (e.g. spring 2023), no significant difference between pasture types was observed at six of the nine farms. Crude protein tended to be higher in multi-species pastures, particularly in summer, whereas metabolisable energy generally did not differ between pasture types. Conclusions Multi-species pastures did not consistently increase total DM production relative to perennial ryegrass pastures over the study period, but increased seasonal DM production at several farms, particularly during summer and autumn. Maintenance of species diversity, especially legumes and herbs, is required for their ongoing performance. Implications Multi-species pastures provide one solution to improving year-round feed in dairy pastures under increasingly variable Australian climates.