Abstract: Anthocyanin-rich black cane (aBC) is a grass rich in lignin and carbohydrates, with
an abundance of anthocyanins. Silages of aBC produced with molasses (MS) and/or ferrous sulphate
(FS) mixtures may have beneficial effects on silage quality and animal performance in ruminants.
However, the addition of MS and FS to ensiled grass is relatively unexplored. Therefore, this study
systematically evaluated the effect of their administration at different doses to select an effective
treatment to modulate the ensiling characteristics of aBC. In the first trial, fresh or pre-ensiled materials
(PBC) were compared with ensiled PBC treated with: 0% MS 0% FS, 4% MS, 8% MS, 0.015% FS,
0.030% FS, 4% MS + 0.015% FS, 4% MS + 0.030% FS, 8% MS + 0.015% FS, and 8% MS + 0.030% FS on
a fresh matter basis. The quality of ensiling characteristics was determined in laboratory-scale silos
after 42 d of preservation. Based on these results, the second trial was further conducted in rumen
cultures to ensure that the selected treatment would not impair rumen fermentation. For this, ruminal
biogases, rumen fermentation profiles, and microbial communities were evaluated. Ensiled PBC
with the incremental addition of MS and FS resulted in the observations for anthocyanin contents
and the ensiling characteristics of the aBC silages. The combination of MS (4%) and FS (0.030%)
incorporated into silages had the highest silage production effect among the experimental treatments.
This combination demonstrated the sustainable mitigation of the ruminal biogases of methane and
carbon dioxide without impairment of total gas production. Concurrently, this combination improved
total volatile fatty acid concentrations, modulated cellulolytic bacteria, and suppressed methanogenic
bacteria in rumen fluids. The results presented here indicated that addition of a mixture of 4% MS
and 0.030% FS to aBC resulted in an optimal balance of ensiling characteristics and is suitable for use
in ruminants.
Keywords: anthocyanin; biogas; fermentation; molasses; ferrous sulphate; ruminant