Características fermentativas e valor nutritivo de silagens de cultivares de palma forrageira contendo níveis de feno de leucena

Abstract

The production of cactus pear silage may optimize the use of this important forage resource in the semi-arid region. However, the low concentration of dry matter (DM) and high concentration of soluble carbohydrates may affect fermentative characteristics of the produced silage. The inclusion of leucaena hay [Leucaena leucocephala (Lam.) Wit] during the cactus pear ensilage process may contribute to increase the silage DM concentration, reduce effluent losses, and improve the fermentative characteristics. The objective of the study was to evaluate the fermentative characteristics, effluent losses, and aerobic stability of three genotypes of cactus pear resistant to carmine cochineal (Dactylopius opuntiae Cockerell) [Orelha de Elefante Mexicana - OEM (Opuntia Stricta (Haw.), IPA Sertânia (Nopalea cochenillifera (L.) Salm Dyck.), and Miúda (Nopalea cochenillifera (L.) Salm Dyck.)], associated with three levels of inclusion of hay from leucena (0, 15 and 30%). The design used was completely randomized, in a 3 × 3 factorial arrangement, corresponding to cactus pear genotypes and leucena hay levels, with four replications. Ensiling was conducted in 36 experimental PVC minisilos containing a Bunsen valve. Gas and effluent losses, organoleptic characteristics, pH,organic acids, and silage nutritive value were evaluated. Data were analyzed using PROC MIXED of SAS®, and treatment means were estimated using "LSMEANS" and compared using "Student” "t" test (P>0.05). Polynomial orthogonal contrasts were used to characterize the type of response to leucaena hay inclusion. There was interaction between cactus pear variety and leucaena hay levels for most of the studied variables. Silages of the OEM cultivar without the inclusion of leucaena hay had a higher pH (4.95) compared to Miúda (4.11) and Sertânia (4.17). The inclusion of leucena hay increased the pH of the silages, reduced losses by effluents, without compromising the fermentative characteristics of the silages, which showed a predominance of lactic acid (93 g/kg). The silages showed aerobic stability for more than 60 hours after opening the silos. The inclusion of leucaena hay in cactus pear silages increased the concentration of crude protein and neutral detergent fiber, and reduced the in vitro dry matter digestibility. The cactus pear varieties showed satisfactory fermentation patterns, however the cactus pear silages of the cultivar Miúda with and without inclusion of leucena hay showed lower concentrations of butyric acid and greater in vitro digestibility of dry matter compared to IPA Sertânia and OEM. The inclusion of 15% leucaena hay in cactus pear silages can be a strategy to reduce DM losses, increase the CP and NDF concentration, without negatively impacting the fermentative profile of the silages.