Preserving Saccharina latissima and Porphyra umbilicalis in Multinutrient Blocks: An In Vitro Evaluation

Seaweeds could be alternative feedstuffs for ruminants, but their utilization in practical feeding is difficult because they deteriorate rapidly. We investigated the possibility of preserving Saccharina latissima and Porphyra umbilicalis in multinutrient blocks (MB), which is a cost-effective preservation method for high-moisture feeds. Three different MB were prepared: without seaweed (control; CMB), with 25% of fresh S. latissima (SLMB), and with 36% of fresh P. umbilicalis (PUMB). Both seaweeds and MB were fermented in vitro with ruminal fluid from sheep. The nitrogen and fiber content of P. umbilicalis was 4- and 4.5-fold greater, respectively, than in S. latissima , but P. umbilicalis produced less gas than S. latissima . Both CMB and PUMB had similar in vitro dry matter degradability (65.8 and 65.1%, respectively), but SLMB had lower values ( p < 0.05; 58.2%). There were no differences among MB in methane and total VFA production, but the VFA pattern was shifted to acetate in SLMB and to butyrate in PUMB. The results indicate that multinutrient blocks could be a feasible option to preserve and store seaweeds for ruminant feeding without compromising ruminal fermentation, but in vivo studies are needed to assess the effects on intake and animal performance.