The main limitation of tropical grasses is their high content of structural carbohydrates, which determine the use of grass by animals. When pastures or forages grow in adverse ecosystems there are important changes in the ruminal degradability of the compounds of interest. The objective was to characterize, at different ages of regrowth, the in situ ruminal degradability of the organic matter of different varieties of Cenchrus purpureus genetically improved to tolerate dry environments. Three drought tolerant varieties (CT-601, CT-603, and CT-605) were taken at different regrowth ages (60, 80, 100, and 120 days). Two fistulated Creole cows of 400 ± 50 kg of live weight were used. The bags were introduced in the rumen for 0, 4, 6, 8, 12, 24, 48, and 72 hours, the estimation of the rumen degradation was made fitting the data to the exponential equation (a + b) * (1-e (-c * t)). The best performance in situ ruminal degradability of the potentially degradable fraction (a + b) of leaves was observed at the age of eighty days, while the effect of the degradation dynamics due to the effect of regrowth age was common for leaves and stems. Fraction degradation values did not exceed 10% for leaves and stems; however, the degradation of b showed values that exceeded 71% for leaves and 30% for stems. The new varieties showed a ruminal fermentation pattern close to 50%, characteristic of tropical grasses.

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<p><strong>Background. </strong>Background. The <em>Moringa oleifera</em> Lam is a fast growing deciduous tree. <strong>Objective</strong>. To evaluate under conditions of Cauto Valley, Cuba, the effect of the combination of cutting height with cutting age in morphological and productive variables in <em>Moringa oleifera</em> vc Criolla. <strong>Methodology</strong>. The evaluations were developed in a design of divided plots with four replicas, the cutting height (0, 10, 20, 30 and 40 cm) was identified as the main plot, and the cutting age (45 and 60 days) as a sub plot. for a total of ten treatments. <strong>Results.</strong> Plant height (103.9 cm) and number of leaves per plant (29.15) were favored (p≤0.05) when the cut was combined at 60 days at 40 cm height, the stem diameter was variable depending on cutting height The green matter yield (GMY) did not show significant differences (P≥0.05) when the cut was used between 10 and 40 cm in height at 60 days (5.62-5.85 t GM / ha-1), at 45 days to All the results were variable, but lower (p≤0.05) than those obtained at 60 days. The DM yield was favored in the same range of cutting height and age as for GMY, and ranged between 1.14-1.73 t DM / ha-1. <strong>Implications.</strong> It is recommended to use this management for the production of fodder in the conditions of the Cauto Valley and evaluate it over time, emphasizing the survival of the plants and sustainability of the forage production. <strong>Conclusions.</strong> The management system evaluated for forage production of <em>Moringa oleifera</em>, contributed an important accumulation of leaves that contributed to acceptable GM and DM productions, the combination that contributed most to this result was the cut at 60 days at 40 cm high.</p>