Management of the prunings of Leucaena leucocephala for forage production in the dry season in Cuba

Ismael Hernández Venereo

ABSTRACT
The objective of this study was to evaluate the effect of cutting’s at the end of the rainy season, on the production and quality of the biomass of Leucaena leucocephala cv. Cunninghan, during the dry season. To accomplish this objective, two experiments were developed in the Experimental Station of Grasses and Forages Indio Hatuey, Matanzas, Cuba. For this purpose a plantation of Leucaena, with more than five years of establishment, was utilized and was planted as indicated: 0.60 m between plants and 3.0 m between arrays. In the first experiment, the factors under study were two months of initial cutting at the end of the rainy season (November and December) and four months of final cutting in the dry season (February, March, April and May), the experimental design utilized was randomized block design with an arrangement 24 with four repetitions. The second experiment was evaluated using similar initial cutting dates like in the first experiment. Two strategies of cutting’s were established in the dry season (February-April vs. April and March-May vs. May). The experimental design utilized was randomized block design with an arrangement 22 with four repetitions. Cuttings were done at 0.45 m of height, which was not fertilized and the weed control was carried out manually, in February. The variables evaluated for the components of the biomass (leave, edible stem, woody stem) were dry matter production, growing rate and proportions of biomass components. Branches production and height of plants were measured. Edible forage determined digestibility in vitro of the dry matter, content of crude protein, phosphorus and calcium as well as crude fiber. The results, of the first experiment, showed that leaf production increased with respect to the initial cut in December. Cuttings carried out in the dry season indicated that leaf production incremented from February to May, detecting significant differences (p< 0.05) with respect to the leaf production in February. Edible stem yields of March presented statistical differences (p< 0.05) in comparison with the others. Edible biomass yield was higher in the initial cutting of December. Total dry matter of Leucaena also incremented at the end of the dry season, detecting differences (p< 0.05) only in February. Longer cutting intervals results in a greater formation of woody stem, which is reflected in an increase of the height of plants. When initial defoliation was done close to the dry season (December), biomass production in fix cutting intervals (90, 120 and 150 days) and growing rate (regrowth) increase. The IVDDM of the leaves and the edible stem did not have variation between the treatments that were studied and the greater content of CP was presented in May. Yields in total CP and dry matter digestibility were incremented in similar forms during the months in the dry season. The content of crude fiber in the edible stem was twice the amount as in the leaves. No differences was found in the contents of Ca and P. In the second experiment, the yields in edible biomass, of the strategy of cutting’s of February-April, was less than the cutting’s in April. In the comparison of cutting’s in May versus the strategy of cutting’s of March-May, one can observe that the leaf yields were superiors in March-May, reaching 1.67 tm of DM/hectare without significant differences (p< 0.05) with cutting’s in May. When the plants were cut in March-May, a tendency existed to increased the total yields of Leucaena with respect to May. The quantities of total CP and dry digestible matter were greater in the treatment March-May. Leucaena leucocephala demonstrated that, under conditions of scarce environmental resources, it is capable of responding to the cutting’s at the end of the rainy period producing adequate quantities of edible biomass during the dry season in Cuba.