Perfil fermentativo de silagens de ração total a base de palma forrageira e sabugo de milho

Abstract

Forage cactus is an important alternative feed for ruminants in semi-arid regions due to its high adaptation to water-restricted conditions and significant biomass production. However, its high moisture content and low concentration of effective fiber require association with ingredients that increase dry matter, especially when intended for silage. In this context, the objective was to evaluate the fermentative profile of total mixed ration (TMR) silages based on forage cactus associated with corn cob. The experiment was conducted in a completely randomized design, with six treatments and five replicates, totaling 30 experimental units. The diets were formulated with different proportions of cactus, corn, corn cob, urea, and soybean meal, and ensiled for 45 days. After opening, pH, lactic acid bacteria populations, yeasts and molds, as well as the concentrations of organic acids (lactic, acetic, propionic, and butyric) were evaluated. A significant effect of the diets on pH and organic acid content was observed (P ≤ 0.001), while microbial populations were not influenced by the treatments. pH values ranged from 3.60 to 4.06, indicating adequate fermentation. The highest concentrations of acetic acid were recorded in TMR1 and TMR2, diets with lower dry matter content and higher urea inclusion, while TMRs with higher dry matter content showed lower concentrations of this acid, evidencing the influence of moisture and nitrogen source on the fermentation pathway. The low levels of butyric acid, especially in TMR3, TMR5, and TMR6, indicated an absence of significant clostridial fermentation, associated with the higher dry matter content of these diets. Considering the set of fermentative parameters, TMR6 stood out for presenting the lowest pH, low butyric acid content, and adequate balance between organic acids, being indicated as the most efficient formulation for silage. It is concluded that total mixed ration silage based on forage palm associated with corn cob presents an adequate fermentation profile and microbiological stability, configuring a viable and technically recommended strategy for production systems in the semi-arid region.