Effects of zinc-bearing palygorskite on rumen fermentation in vitro.

Objective: The aim of the study was to investigate the effect of zinc-bearing palygorskite (Zn-Pal) on rumen fermentation by in vitro gas-production system.

Methods: In trial, 90 incubators were evenly divided into five groups: control (0 % Zn-Pal), treatment Ⅰ (0.2 % Zn-Pal), treatment Ⅱ (0.4 % Zn-Pal), treatment Ⅲ (0.6 % Zn-Pal) and treatment Ⅳ (0.8 % Zn-Pal). The contents of zinc fortreatments were 0, 49, 98, 147, 196 mg/kg, respectively. The main chemical composition and microstructure of Zn-Pal was investigated by X-ray diffraction. The physicochemical features were evaluated by Zeta potential analysis, cation-exchange capacity, ethylene blue absorption and specific surface area (the BET method). In vitro gas production (GP) was recorded at 3, 6, 9, 12, 18, 24, 36, 48, 60 and 72h incubation. Incubation was stopped at 0, 6, 12, 24, 48 and 72h and the inoculants were tested for pH, microbial protein yield (MCP), NH3-N, volatile fatty acids (VFAs), Lipopolysaccharide (LPS).

Results: The results showed that the GP in the treatment groups has no significant different than in the control groups (P>0.05). Compared to the control group, pH was higher at 24h, 48h (P<0.05) and 72h (P<0.01) (range 6-7). The concentration of NH3-N in the three treatment groups was higher than in the control group at 24h (P<0.01), meanwhile, it was lower at 48h and 72h (P<0.01), except in the treatment Ⅳ. The concentration of microbial protein yield (MCP) in treatment Ⅰ group was higher than in the control at 48h (P<0.01). Compared with control, the lipopolysaccharide (LPS) concentration in treatment Ⅲ became lower at 12h (P<0.05). Total volatile fatty acids (VFA) in treatments were higher than in the control at 24h, 48h (P<0.05).

Conclusion: These results suggest that the addition of Zn-Pal can improve the rumen fermentation, especially when adding 0.2% Zn-Pal.