SPECIAL STORY 56 FEED & ADDITIVE MAGAZINE July 2023 SEAWEED BLENDS ARE A COST-EFFECTIVE ALTERNATIVE TO CONVENTIONAL GUT-HEALTH ADDITIVES Previous research has demonstrated the potential for macroalgae blends to replace both antibiotic growth promoters and therapeutic levels of zinc oxide in the diet of nursery pigs, with improvements in gut health and performance mediated by the beneficial effects of the seaweed polysaccharides on the diversity and abundance of key bacterial populations in the GI tract (Sands, 2022; Hutchinson 2023). Due to societal concerns, regulators in a number of markets around the world have banned the use of antibiotics and medicinal zinc oxide in swine diets. In such markets, producers have turned to a range of feed additives designed to support gut health, such as phytogenics, pre- and probiotics, organic acids and yeast products. The wide range of bioactive properties in seaweed provide solid justification for the use of seaweed blends as an alternative to these traditional gut health additives. In a trial in nursery pigs in Spain, the performance and production economics of two groups of pigs fed different dietary treatments was compared in the nursery phase. In one group, the positive control, pigs were fed a standard diet plus a combination of traditional gut health additives designed to support gut health. These additives included butyrate, yeasts, organic acids, mycotoxin binders and phytogenics. The second group was fed the standard diet, with none of the above gut health additives, but with a blend of red, green and brown seaweed (OceanFeed™ Swine; OFS). Feed intake, average daily gain and feed conversion were not significantly different between the treatment groups, but were numerically improved in pigs supplemented with OFS. Faecal scores were significantly improved by OFS supplementation (from 2.10 to 1.72, where 0 is good and 5 is poor), indicating improved gut health in this group of pigs. The numerical improvements in weight gain and feed conversion ratio, combined with a lower feed cost for the OFS-supplemented group, resulted in a tendency (P=0.07) towards lower feed costs per kg gain in the pigs consuming diets supplemented with OFS, compared to those consuming the traditional gut health additive diet. CONCLUSIONS There is growing interest in the use of seaweed in animal nutrition, with an extensive body of scientific research demonstrating the functional compounds present in macroalgae, their bioactivity, and potential applications in animal feed. The production of seaweed, and in particular the wild harvesting of algal blooms, presents a valuable opportunity for the animal nutrition industry to enhance the sustainability of feed production, in conjunction with realising the benefits of macroalgal supplementation on animal health and performance. To date, a number of studies have identified the prebiotic effects of soluble and sulphated polysaccharides as a key mode of action of seaweed products, enhancing the diversity of the gut microbiome and the abundance of butyrate-producing bacteria in a number of animal species. Ongoing research is investigating additional bioactivity of polysaccharides and other functional macroalgae components, with potential to exploit the reported antioxidative, anti-inflammatory, antimicrobial and immunomodulatory effects of different seaweed species. Commercial trials have been conducted that demonstrate the improvements in animal health and performance across species and applications, showing the economic benefits of using seaweed supplements. Taken together, the scientific research and commercial studies indicate a vital role for functional seaweed supplements in a sustainable future for the animal nutrition industry. About Ian Hutchinson Dr Ian Hutchinson is Technical Director at Ocean Harvest Technology, having previously worked for 9 years in the feed additives and premix industry. In his role as Technical Director, Ian is responsible for developing and driving the Ocean Harvest Technology’s research and development agenda as well as customer technical support and product trials.
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