The objective of this experiment was to determine the effects of increasing doses of a seaweed extract (Ecklonia radiata; SWE) and SWE with quebracho (Schinopsis quebrachocolorado) tannin extract (TE) on in vitro fermentation.
Two in vitro experiments were conducted using the Daisy II incubator, where repeated measurements were taken. In Exp. 1, treatments were increasing levels (0, 2, 9.5, or 31.5 μL per fermentation jar) of the SWE, and in Exp. 2, treatments were either no SWE or TE (CON), the optimal dose (the regression minimum) determined from Exp. 1 of SWE only (SWO), 4 mg of TE and SWO (LTS), or 10 mg of TE and SWO (HTS).
There were no time-by-dose interactions (P ≥ 0.13) in either experiment. Only the NH3 from the 2-μL dose was different (P = 0.04) from the 0-μL dose. No other differences (P > 0.10) were detected in Exp. 1. A mixed model regression determined a cubic relationship between dose and NH3 (P = 0.02), with the minimum at 5 μL. In Exp. 2, SWO reduced (P = 0.02) NH3 compared with all other treatments. The SWO treatment also reduced total VFA compared with the other treatments (P = 0.01). The LTS and HTS were not different from the CON for any variables (P > 0.1).
Under the context of this experiment, we conclude that low levels of SWE reduce ruminal NH3 and suggest that urinary N may be reduced in vivo, but this was negated in the presence of condensed tannins.
