DEGRADABILITY in situ OF THE DRY MATTER OF Tithonia diversifolia (Hemsl.) A. Gray IN THREE SEASONS OF THE YEAR

Background. Forage trees and shrubs are an alternative that improve dry matter intake and digestibility in ruminants, due to their high ruminal degradation rate, higher nitrogen contribution for rumen microorganisms, low percentage of neutral and acid detergent fiber. Objective. To estimate the availability, nutritional quality and degradability for Tithonia diversifolia (Hemsl.) A. Gray were estimated at different cutting age, in three seasons of the year. Metodology. Forage production and nutritional quality were measured every 14 d, from cutting to 84 d of age. Leaf and stem samples were taken to determine crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and the "in situ" degradability of dry leaf matter (DM). Results. Total DM production was similar in autumn and winter, and both were greater than for spring. In autumn, at 56 d and in winter at 70 d after cutting, DM production was 9 t ha-1, while in spring at 84 d it was close to 3 t ha-1. Crude protein content increased linearly with days after cutting. Implications. In autumn and winter, the highest percentages of NDF and ADF were observed. Plants at 42 d of regrowth had a lower percentage of ADF. Conclusions. The DM production and the nutritional quality of T. diversifolia differ according to the season of the year and the age of regrowth, at 42, 70 and 84 days of regrowth in autumn, winter and spring, respectively, under the agroecological conditions of the growing area. study, the best conditions for growth occur in Autumn. The DM degradability is similar between the ages of 42, 56 and 70 days of regrowth. However, harvesting plants at 42 days could sacrifice biomass yield at a very early age.