Growing up in west Clare, John O’Doherty remembers his father feeding carrageen seaweed to calves. “We laughed as he boasted of its benefits,” he said.
Fast forward to 2017 and as professor of monogastric nutrition at UCD, his exploration of the effects of adding seaweed to the diet of pigs is attracting lots of attention.
“In modern pig production, weaning is a major stress in the pig’s life. The occurrence of post-weaning diarrhoea and the subsequent growth check cause large economic losses for the pig industry worldwide,” said Dr. O’Doherty, who has published over 200 peer-reviewed full-length papers in international journals.
Traditional measures to reduce weaning-associated intestinal disorders have centred on dietary inclusion of antibiotic growth promoters (AGP) in weaning pig diets, or high concentrations of dietary minerals in the form of zinc oxide at doses well above nutritional requirements, said Dr. O’Doherty who received a DSc in published works in 2014.
“The direct purpose of these additives is to suppress the growth of pathogenic bacteria such as escherichia coli and salmonella. The overuse of antibiotics is closely related to the growing number of antimicrobial-resistant agents and raises important concerns about animal and also human health. As a result, the EU implemented a full ban on AGP usage in livestock diets in January 2006,” he said.
There is also pressure in other pig-producing regions worldwide to minimise or completely eliminate the inclusion of in-feed antibiotics in livestock diets and there are concerns regarding the feeding of pharmacological doses of zinc oxide to pigs.
“This is due to the relationship between zinc oxide usage and an increase in antibiotic resistance and zinc accumulation in the environment,” said Dr. O’Doherty, winner of the 2016 British Society of Animal Science Hammond award, and a Fellow of the Royal Society of Biology.
A diverse range of feed additives has been researched in order to replace in-feed AGP. “The focus of some of our swine research at UCD over the last 10 years – along with my wife, Prof. Torres Sweeney, professor of animal genomics – is to find alternatives to in-feed antibiotics. One of the alternatives being investigated is seaweed extracts.”
Historically, seaweeds have always been known for their medicinal properties. “Seaweed extracts are now showing a wide range of biological activities – anti-oxidant, anti-cancer, anti-coagulant and anti-inflammatory activities among others – with potential use in the food and nutraceutical markets,” he said.
Brown seaweeds, Dr. O’Doherty said, contain polysaccharides like laminarin, fucoidan and alginate. The UCD research has shown that whole milled seaweed and whole seaweed extracts have very limited value in pig diets but the sugars laminarin and fucoidan in particular are most interesting with potent biological activities in pigs.
Our research has shown that the supplementation of a seaweed extract containing laminarin to weaned pigs suppressed faecal e. coli numbers and improved performance post-weaning.
“These results suggest that laminarin benefits the gastrointestinal microflora of pigs mediated by potent antibacterial effects and had a growth performance similar to zinc oxide. A suppressed enteric e. coli population may ultimately help alleviate the incidence and severity of post-weaning diarrhoea in pigs.
“Other effects were also evident as inclusion of seaweed extracts containing predominantly fucoidan in the diet of pigs decreased lipid oxidation in meat products and increased total antioxidant capacity in the meat muscle of the supplemented pigs and extended the shelf life of the pork by approximately five to seven days.
“Truly Irish Ltd is now exploiting this technology to extend the shelf life of its products without the use of chemicals and to increase the anti-oxidant and health benefits of pork.”
Traditional measures to improve weaning-associated intestinal dysfunction in pigs, he said, have focused on dietary manipulations post-weaning.
The UCD research showed that dietary laminarin and fucoidan supplementation of sows enhanced colostral IgG concentrations and serum IgG concentrations of suckled piglets. This, he said, suggests an immunomodulatory property of the laminarin-fucoidan mix responsible for the elevated colostral IgG concentrations.
“While maternal supplementation with seaweed extracts appears to have enhanced the immunoglobulin status of the piglets, it also appears to have enhanced the ability of the piglets to fight pathogenic bacterial challenges.
Piglets suckling sows supplemented with seaweed extract containing laminarin and fucoidan had improved resistance to e. coli infections and reduced shedding of this pathogen post-weaning following an e. coli challenge. Also piglets suckling sows supplemented with laminarin had improved resistance to an experimental salmonella challenge and reduced shedding of this pathogen post-weaning.
In a longer-term study, sows were supplemented with laminarin and/or fucoidan from day 87 of gestation and the offspring were monitored until time of slaughter, approximately 90 kg.
Pigs from laminarin and/or fucoidan supplemented sows had greater nutrient digestibility, greater villous architecture and gut absorption capacity at weaning and had higher daily gain than control pigs for the duration of the studies.
“The biological response of the seaweed extracts will differ depending on the variety of seaweed used, method of extraction and season of harvest,” he said. These extracts are now been produced by Bioatlantis Ltd, Tralee, Co Kerry, and will be available on the commercial market in the next six to 12 months.