Nguyen Van Sao et al., 2010. Livest. Res. Rur. Dev., 22 (8): 151

Three experiments were carried out at the Goat and Rabbit Research Centre and on farms in Bavi, Ha Tay province of North Vietnam. In the first experiment, biomass production of Tithonia diversifolia (Wild Sunflower) and the effect on soil fertility was studied in a complete random plot design with three treatments: (TD) Tithonia in pure stand; (GG) Guinea grass in pure stand; and TD-GG Association of Tithonia and guinea grass. Cattle manure (10 tonnes/ha/year) was supplied for all plots. Soil fertility changes were monitored with the bio-test method by using maize plants grown in the soil taken from experimental plots before and at the end of the trial. The second experiment was a 3*3 Latin square design to determine apparent digestibility and nitrogen retention when goats were fed Tithonia as sole feed compared with foliage of Stylosanthes and Jackfruit. In the third experiment, feed intake was recorded in a trial with 5 treatments: (TD) Tithonia as sole feed fed ad libitum; (TD-GG) Tithonia fed ad libitum+1.5% of LW (DM basis) of guinea grass; (TD-GG-JA) Tithonia fed ad libitum+1.5% LW of guinea grass+1% LW of Jackfruit foliage, (TD-GG-BL); Tithonia fed ad libitum+1.5% LW of guinea grass+1% LW of Banana leaf; and (TD-GG-CA) Tithonia fed ad libitum+1.5% LW of guinea grass+1% LW of Caliandra foliage. After 12 months growth, the edible biomass yield of Tithonia was 172 tonnes/ha/year in fresh form equal to 25 tonnes DM with 6 tonnes crude protein (CP)/ha/year when Tithonia was planted in pure stand. Soil fertility was improved according to maize biomass yield grown in the soil taken from plots planted with Tithonia. Foliage of Tithonia contained 23.9% CP (DM basis) and had low NDF content (38.4%). Apparent digestibility coefficients of DM and CP were 53.7% and 67.8%, respectively, higher than for Jackfruit foliage (51.52% and 38.37%) and Stylosanthes (51.0% and 62.3%). However, nitrogen retention of goats when fed Tithonia as sole feed was lower than that obtained with Jack fruit foliage and Stylosanthes. Urine N was 15.8 g/day on Tithonia compared with 5.7 and 7.2 on Jackfruit and Stylo, indicating that a high proportion of the feed N was degraded in the rumen and excreted in the urine. It is concluded that Tithonia plants have high biomass yield per unit of land and could improve soil fertility. Foliage of Tithonia is well consumed by goats but needs appropriate supplementation for the expression of its potential nutritive value.