CHEMICAL-NUTRITIONAL COMPOSITION OF VARIETIES OF Cenchrus purpureus (Schumach.) Morrone DURING THE RAINY SEASON

Background: The rainfall regime and its distribution define the productivity and quality of the pastures for use as forage. Objective: Evaluate changes in the chemical-mineral composition and nutritional value of Cenchrus purpureus sprouts in the rainy season. Methodology: A study was developed in a completely randomized design in factorial arrangement, with varieties of C. purpureus (CT-601; 603 and 115 as control) at different regrowth ages (60, 80, 100 and 120 days) and their interaction 4 x 3, for a total of twelve treatments with four repetitions. Results: The second degree interaction affected the structural composition of the cell wall in leaves, increasing (P≤0.001) the fiber concentration in acid detergent (FAD) as the age of the plant advanced, while lignin (LAD), cellulose (Cel) and hemicellulose (Hcel) showed erratic behaviors at different ages in the three varieties (P≤0.001). In the whole plant (WP), the FAD and FND decreased (P≤0.001) as a function of the increase in age, LAD, Cel and Hcel showed the same pattern as in leaves, differing (P≤0.001) between varieties with respect to the control in the different ages. The highest in vitro degradability’s of dry matter (IDDM) and organic (IDOM) in leaves were centered at the age of 60 days in the varieties CT-603 and 115, respectively, in WP at 100 days in CT-601 and 603 (P≤0.001) compared to CT-115. Implications: The varieties CT-601 and CT-603 do not show affectations in the structure of the cell wall that affect the nutritional value with respect to the control treatment (variety CT-115). Conclusions: Varieties, depending on DR, modify the structure of the cell wall, without affecting their nutritional value.