SPECIAL STORY FEED & ADDITIVE MAGAZINE July 2023 53 and Gonçalves, 2022), with properties such as anti-inflammatory, antioxidant, antimicrobial, anticarcinogenic and immune-modulating functions all attributed to seaweed polysaccharides and their derivatives (Xie et al., 2023). There is also strong evidence to demonstrate the prebiotic effects of seaweed polysaccharides on the GI microbiota, with subsequent beneficial effects on nutrition and health (Sardari and Karlsson, 2018; Cherry et al., 2019; Shannon et al., 2021). Polysaccharides typically comprise of 30-75% of the dry matter of macroalgae, with 55-65% of total polysaccharides in Green and Red Seaweeds in the form of soluble fibre, and even higher content found in the Ascophyllum and Laminaria species of Brown seaweeds (Lahaye, 1991). The soluble nature of these polysaccharides is an important characteristic, as is their ability to resist gastric acidity, digestive enzymes and GI absorption, making them attractive as functional prebiotics in the animal hindgut (O’Sullivan et al., 2010, Hentati et al., 2020). Another characteristic that differentiates some seaweed polysaccharides from those found in landbased plants is their sulphated nature, and these sulphated polysaccharides have been shown to have additional bioactivity, such as inhibition of pathogenic bacteria (De Jesus Raposo et al., 2015, McDonnell et al., 2010). Recent in vitro trial work carried out by Ocean Harvest Technology investigated this point further, in a study designed to elucidate the mode of action of their seaweed blends in supporting animal health and performance. The objective of this study was to assess the potential for OceanFeed™ seaweed blend to bind two common pathogens (Clostridium perfringens and Escherichia coli) and form agglomerates. The binding efficacy of OceanFeed™ was compared with a negative control, and with a positive control (a commercial yeast cell wall product commonly used in animal diets as a pathogen binder). Pathogen binding capacity was assessed at pH 6.5 (neutral, representing the small intestine) and pH 2.5 (acidic, representing stomach conditions). OceanFeed™ enhanced pathogen agglomeration of both C. perfringens and E. coli compared with both the negative and positive controls. This effect was observed in a dose-dependent manner up to a maximum of 60% and 42% agglomeration of C. perfringens and E. coli, respectively (Figure 1). The positive control did not demonstrate any clear agglutination capacity for either pathogen tested. Figure 1. Pathogen agglomeration capacity of OceanFeed™ seaweed blend and a Yeast Cell Wall positive control (100% represents no agglomeration)
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