ARTICLE | doi:10.20944/preprints202208.0186.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: rumen simulation technique; methane production; seaweed; rumen fermentation
Online: 10 August 2022 (03:35:34 CEST)
Several red seaweeds have shown to inhibit enteric CH4 production; however, adaptation of fermentation parameters to their presence is not well understood. The objective of this study was to examine the effect of three red seaweeds (Asparargopsis taxiformis, Mazzaella japonica, Palmaria mollis) on in vitro fermentation, CH4 production, and adaptation using the rumen simulation technique (RUSITEC). The experiment was conducted as a completely randomized design with four treatments, duplicated in two identical RUSITEC apparatus equipped with eight fermenter vessels each. The four treatments included the control (barley straw and barley silage) and the three red seaweeds added to the control diet at 2% diet DM. The experimental period was divided into four phases including a baseline phase (d 0-7; no seaweed included), adaptation phase (d 8-11; seaweed included in treatment vessels), intermediate phase (d 12-16) and a stable phase (d 17-21). The digestibility of organic matter (P = 0.04) and neutral detergent fibre (P = 0.05) was decreased by A. taxiformis during the adaptation phase, but returned to control levels in the stable phase. A. taxiformis supplementation resulted in a decrease (P < 0.001) in molar proportions of acetate, propionate and total volatile fatty acid (VFA) production, with an increase in molar proportions of butyrate, caproate, and valerate; the other seaweeds had no effect (P > 0.05) on molar proportions or production of individual VFA. A. taxiformis was the only seaweed to suppress CH4 production (P < 0.001), with the suppressive effect increasing (P < 0.001) across phases. Similarly, A. taxiformis increased (P < 0.001) the production of hydrogen (H2, %, mL/d) across the adaptation, intermediate and stable phases, with the intermediate and stable phases having greater H2 production than the adaptation phase. In conclusion, M. japonica and P. mollis did not impact rumen fermentation or inhibit CH4 production within the RUSITEC. In contrast, we conclude that A. taxiformis is an effective CH4 inhibitor and its introduction to the ruminal environment requires a period of adaptation; however, the large magnitude of CH4 suppression by A. taxiformis inhibits VFA synthesis, which may restrict production performance in vivo.