• Energy Research

In order to meet consumer needs, the livestock industry is increasingly seeking natural feed additives with the ability to improve the efficiency of nutrient utilization, alternatives to antibiotics, and mitigate methane emissions in ruminants. Chitosan (CHI) is a polysaccharide with antimicrobial capability against protozoa and Gram-positive and -negative bacteria, fungi, and yeasts while naringin (NA) is a flavonoid with antimicrobial and antioxidant properties. First, an in vitro gas production experiment was performed adding 0, 1.5, 3.0 g/kg of CHI and NA under a completely randomized design. The substrate containing forage and concentrate in a 70:30 ratio on a dry matter (DM) basis. Compounds increased the concentration of propionic acid, and a significant reduction in methane production was observed with the inclusion of CHI at 1.5 g/kg in in vitro experiments (p < 0.001). In a dry matter rumen degradability study for 96 h, there were no differences in potential and effective degradability. In the in vivo study, six crossbred heifers fitted with rumen cannulas were assigned to a 6 × 6 Latin square design according to the following treatments: control (CTL), no additive; chitosan (CHI1, 1.5 g/kg DMI); (CHI2, 3.0 g/kg DMI); naringin (NA1, 1.5 g/kg DMI); (NA2, 3.0 g/kg DMI) and a mixture of CHI and NA (1.5 + 1.5 g/kg DMI) given directly through the rumen cannula. Additives did not affect rumen fermentation (p > 0.05), DM intake and digestibility of (p > 0.05), and enteric methane emissions (p > 0.05). CHI at a concentration of 1.5 g/kg DM in in vitro experiments had a positive effect on fermentation pattern increasing propionate and reduced methane production. In contrast, in the in vivo studies, there was not a positive effect on rumen fermentation, nor in enteric methane production in crossbred heifers fed a basal ration of tropical grass.

One viable option for meeting global energy demand is the creation of biofuels from plant species that demonstrate high biomass productivity and good energy characteristics. In this study, growth was evaluated using plant height (PH), the production of green (GB) and dry biomass (DB), and the energy quality of leaves, pods, and stems, considering apical and basal sections of maralfalfa plants at 28, 60, 90, and 140 days after applying a uniformity cut (AUC). The variables were analyzed with correlation tests and variance analyses (ANOVA) using a factorial array design; in addition, Tukey tests were performed. A steady increase in PH (72 to 239 cm) was found. The highest yield of stems was at 90 AUC (41,362 kg/ha) for GB and 140 days AUC (6331 kg/ha) for DB, and a high correlation was observed between PH and stem biomass production for both the GB (r = 0.91) and DB (r = 0.93). There was a strong correlation between higher heating value and DB from the apical stratum (r = 0.99) and the basal stratum (r = 0.97). Maralfalfa shows high biomass productivity and high energy production in short growth periods.