Avaliação do processo fermentativo, composição química e estabilidade aeróbia de silagem de dieta total com inclusão de torta de oliva

Abstract

Most recently, the use of total mixed ration (TMR) silage on dairy and beef cattle system has increased. Ensiling TMR allows the use of by-products (especially those with high moisture) from agro-industrial chains on livestock production. Therefore, the main objective of this study was to evaluate the effect of the inclusion of different doses of crude olive cake (OC) on the fermentation process, chemical composition and aerobic stability of TMR silages. Secondarily, wheat forage was assessed as a basis for constituting a TMR. The treatments examined were produced as follow: exclusive wheat silage and TMR silages composed of different doses of OC (0, 5, 10 and 20%, as dry matter (DM) basis; the treatments were named as TMR0, TMR5, TMR10 and TMR20, respectively). Laboratory silos (PVC tubes with a capacity of 2.5 L) were used and they remained closed for 97 days. After the silos were opened, the aerobic stability of the silages was evaluated for 10 days. The experiment was carried out under a completely randomized design, with four replications (laboratory silos) per treatment. Four orthogonal contrasts were tested, as follows: (i) Wheat vs. TMR; (ii) SO vs. OC (TMR without olive cake versus TMRs with olive cake); (iii) 5OC vs. 10OC; and 10OC vs. 20OC. The OC doses determined prior to begin the experiment were correct for the DM content of each ingredients and, indeed, the OC doses used in the current study were 0, 4, 8 and 17% (on DM basis). The DM losses were greater in the TMR silages containing OC (SO = 1,39% DM and OC = 2,63% DM; P = 0.05). The inclusion of OC did not increase effluent production (general average = 9.38 kg/t fresh matter; P = 0.66). Aerobic stability, aerobic deterioration, heating rate and DM losses after the exposure of TMR silages to oxygen were unaffected (P > 0.05) due to inclusion of OC. Wheat silage had low DM loss (1.43% of DM), aerobic stability higher than 80 hours and good chemical composition (crude protein = 11.1% of DM and neutral detergent fiber = 51.8% of DM). Currently, the OC is a problem for the olive production chain and therefore, it is needed to find a suitable fate for this by-product. In this regard and based on the data from this experiment, it is concluded that a OC can be included in a TMR up to 17% based on DM. Additionally, the wheat forage can be used for silage production either exclusively or as based-forage for a TMR.