S. TUDSRI¹, Y. ISHII³, H. NUMAGUCHI³ and S. PRASANPANICH²

¹Department of Agronomy, and
²Department of Animal Science, Kasetsart University, Bangkok, Thailand
³Department of Biological Production and Environmental Science, Miyazaki University, Miyazaki, Japan

Abstract

Leucaena (Leucaena leucocephala) was grown with 3 grasses: ruzi (Brachiaria ruziziensis), and dwarf napier and Taiwan A25 (both Pennisetum purpureum) under rainfed conditions in Thailand. The pastures were cut at 20, 30 and 40-day intervals for 840 days. Dwarf napier produced more total and leaf dry matter than Taiwan A25 and ruzi (P < 0.05). Yield of all grass species increased with increasing cutting intervals. Leucaena yield was generally unaffected by cutting interval. However, at 40-day cutting intervals, leucaena dry matter yield was lower in the dwarf napier plots than in the ruzi and Taiwan A25 plots, which produced similar legume yields (P > 0.05). Growing leucaena with dwarf napier gave the lowest total legume dry matter yield (P > 0.05). Less frequent cutting increased total dry matter yields in all combinations through increases in grass yield. Maximum dry matter yield (41.5 t/ha) was produced by leucaena-dwarf napier.
Dwarf napier produced herbage of higher quality than the other grass species in terms of crude protein concentration in both stems and leaves and had a higher leaf : stem ratio. Leucaena produced higher crude protein levels than grasses. The crude protein concentration in stems and leaves of all species decreased with increasing cutting intervals. Phosphorus concentrations in leucaena and associate grasses were similar and declined little with age. Leucaena was lower in potassium but higher in calcium concentration than the associated grasses.
The results of this study are discussed in relation to the management of leucaena in mixed pastures for dairy production in Thailand.