## 3 Results and Discussion
### Chemical Composition and Characteristics of Silages
It has been reported that treating silages with ammonia or urea results in increased acetic concentrations due to prolonged fermentation, caused by its buffering effect [21]. The CON silage presented greater concentrations (\(p<0.05\)) of propionic and butyric compared with the three silages treated with additives. The concentrations of these acids in the silage should be minimal, and preferably undetectable, as they are indicative of fermentation by clostridial microorganisms [8]. Clostridal fermentation can be avoided by the rapid production of lactic acid in the silage, as clostridial microorganisms cannot tolerate high osmotic pressure and low pH conditions that are favored by high concentrations of lactic acid. Although the addition of all additives increased (\(p<0.005\)) the concentrations of lactic acid compared with the CON silage (Table 1), the lactic acid concentrations were lower than the values ranging from 20 to 40 g/kg DM silage reported by [PERSON] et al. [8] as the mean values for commonly fed silages. Moreover, the lactic acid/acetic acid ratio in good fermented silages is usually 2.5-3.0 [8], and in our study were below this value (0.32, 1.62, 0.41, and 1.37 for the CON, FA, UM, and FAUM silages, respectively). Altogether, the results indicate that lactic acid production was low in all silages, and that clostridial fermentations could have been produced in UM and FAUM silages, as indicated by the presence of butyric acid, high pH, and high concentrations of acetic and NH\({}_{3}\)-N [8]. The chemical composition of the silages, the pre-ensiling typha, and triticale hay used as a reference is shown in Table 2. Compared with the CON silage, the addition of formic acid reduced (\(p<0.05\)) the ash content, whereas the addition of urea and molasses (FAUM silage) increased this content (\(p<0.05\)). Although some studies [29,30] have reported that formic acid can cause a decrease in NDF concentrations of ensiled plants due to acid hydrolysis, in our study, this effect was only observed when formic acid was combined with urea and molasses in FAUM silage, which showed lower NDF concentrations than the CON silage. There were no differences between the silages in their ADF and EE content (\(p=0.581\) and 0.081, respectively). As expected, the addition of urea (UM and FAUM silages) caused an increase (\(p<0.05\)) in CP content compared with CON and FA silages, which was greater in the FAUM silage probably due to the protective effect of formic acid against CP degradation. The lower concentrations of NH\({}_{3}\)-N and the undetectable concentrations of isobutyric, isovaleric, and valeric acids observed in FAUM silage seem to support this hypothesis. The chemical composition of the typha used in the present study was similar to that reported by [PERSON] et al. [4] for samples of _Thypha domingensis_ collected in Nigeria and by [PERSON] and [PERSON] [31] for _Thypha domingensis_ collected in Costa Rica. Different factors such as plant maturity, soil characteristics, climate, etc., can influence the chemical composition of typha [4]. As expected, the addition of urea increased the CP content in UM and FAUM silages compared with the pre-ensiling typha (Table 2). The chemical composition of CON and FA silages was similar to that of the pre-ensiling typha, with the exception of EE content, which was numerically lower. A decrease in EE content during the ensiling process has been reported previously, and it was attributed to the activity of lipoxygenases found in the plants [32]. The triticale hay used as a reference in this study had a similar CP content to the pre-ensiling typha, but lower EE, NDF, ADF, and lignin contents.