Effects of type of ionophore and carrier on in vitro ruminal dry matter disappearance, gas production, and fermentation end products of a concentrate substrate

Effects of ionophore type and carrier on in vitro ruminal digestion and fermentation patterns of a concentrate substrate were evaluated at various incubation times. Treatments were: control (no ionophore); lasalocid sodium commercial premix (Bov); lasalocid sodium mycelium cake (LasBio); laidlomycin sodium salt (LaidNa); laidlomycin propionate commercial premix (LaidPro); monensin sodium salt (Mon); and monensin sodium commercial premix (Rum). The Bov, LasBio, Mon, and Rum treatments supplied 4μg of ionophore/mL of culture volume, whereas the LaidNa and LaidPro treatments supplied 1.33μg of ionophore/mL. Total gas and methane production did not differ among treatments at any of the incubation times (P>0.09). Similarly, in vitro dry matter disappearance (IVDMD) was not affected by treatment (P>0.28) at 6, 18, and 24h of incubation; however, IVDMD (P=0.03) was greater for ionophores than for the control at 12h of incubation. Molar proportions of acetate (P