Difference in yield and persistence among perennial forages used by the dairy industry under optimum and deficit irrigation

Perennial ryegrass ( Lolium perenne L.) is the dominant forage grazed by dairy cows in Australia; however, poor persistence has led to an increasing interest in alternative forages. This study was conducted to identify more productive and/or persistent perennial forage species than perennial ryegrass. We evaluated 15 perennial forages under optimum irrigation (I1) and 2 nominated deficit irrigation (I2, 66% of irrigation water applied to I1; I3, 33% of irrigation water applied to I1) regimes, over 3 years at Camden, NSW (34°3′S, 150°39′E), on a brown Dermosol in a warm temperate climate. The forages were: perennial ryegrass, cocksfoot ( Dactylis glomerata L.), phalaris ( Phalaris aquatica L.), prairie grass ( Bromus catharticus M. Vahl), tall fescue ( Schedonorus phoenix (Scop.) Holub), kikuyu ( Pennisetum clandestinum Hochst. ex. chiov.), paspalum ( Paspalum dilatatum Poir.), birdsfoot trefoil ( Lotus corniculatus L.), lucerne ( Medicago sativa L.), red clover ( Trifolium pratense L.), strawberry clover ( Trifolium fragiferum L.), sulla ( Hedysarum coronarium L.), white clover ( Trifolium repens L.), chicory ( Cichorium intybus L.), and plantain ( Plantago lanceolata L.). Under non-limiting conditions of water and fertility, tall fescue, kikuyu, and prairie grass had the highest mean annual yield over the 3 years of this experiment (24.8–25.5 t dry matter (DM)/ha), which was significantly greater ( P