Effects of Cutting Management on a Desmodium intortum (Mill.) Urb / Setaria sphacelata (Schumach.) Mixture

A study was conducted to determine the influence of two heights (8 and 20 cm) and three frequencies of cutting (3, 6 and 9 weeks) on the yield, botanical composition, and nutritive value of Desmodium intortum (Mill.) Urb grown in association with Setaria sphacelata (Schumach.). The mixture was established on a latosol soil at Kabanyolo, Uganda. Herbage samples were hand separated to ascertain botanical composition. Crude protein (CP) and in vitro dry matter (IVDM) analyses were determined for each species for all cutting treatments. Annual dry matter yields of the mixture ranged from 5.67 to 14.97 mt/ha. The productivity of the mixture was enhanced as the tune of the cutting interval increased. No notable yield differences were found between cutting heights. Close frequent clipping had a deleterious effect on D. intortum. The slow recovery of this legume after close cutting led to a rapid increase in the grass and weed components. The CP content of D. intortum was more than double that of S. sphacelata. There were significant differences in CP content among cutting irequencies in S. sphacelata. As the time of the cutting interval increased, the CP content decreased. In vitro dry matter digestibilities of S. sphacelata varied from 61.9 to 68.2%. As the time of the cutting interval increased, the IVDM percent digestibilities of S. sphacelata decreased. There were no notable differences among IVDM digestibility percentages of D. intortum. This study demonstrated that the productivity and persistence of D. intortum were greatly influenced by the clipping treatments applied. Results clearly indicated that proper cutting management is needed in order to maintain the legume in the mixture. Long cutting intervals (6 to 9 weeks) at 20-cm height were essential to keep D. intortum in adequate amounts when grown in association with S. sphacelata. The CP percent and degree of in vitro digestibility indicated that a balanced D. intortum/S. sphacelata mixture would adequately meet the nutritional requirements of grazing animals.