Success story: Plants and their extracts and other natural alternatives to antimicrobials in feeds // FP6-2002-FOOD-1-506487
A multiple success story
This project was formulated to examine plants, plant extracts and other natural materials as safe alternatives to antimicrobial growth promoters (AGP) in livestock production. AGP were banned from use in the EU at the beginning of 2006. The candidates were derived from 500 samples of plant materials collected previously as possible feed additives for ruminants [FP5 project, Rumen-up, QLK5-CT-2001-00992], plus some additional natural materials likely to be useful in non-ruminants. Rumen-up samples, for which a large data set of background information and screening success existed, were re-collected to ensure fresh samples. They were tested for properties not screened in FP5: their possible impact on human and animal health (Escherichia coli, parasites), food quality (fatty acids in ruminant products) and efficient use of natural resources (increased forage use by ruminants). Researchers on pigs, poultry and fish, where the impact of antibiotic withdrawal is greatest, joined the consortium. Their aims were to find plant materials that prevented early-weaning diarrhoea in piglets, that prevented necrotic enteritis in poultry, and that improved feed efficiency in cold-water aquaculture.
The most exciting discovery was one that had benefits to both pig and poultry production. A species of North European tree, which cannot be named at this time for patent reasons, was found to produce a fruit that, especially when immature, killed E. coli K-88, the main cause of early-weaning diarrhoea in piglets. Initial in vitro experiments were followed by successful trials carried out under production conditions. The same sample also suppressed the growth of Clostridium perfringens, which is the bacterium that causes necrotic enteritis in poultry. Poultry also benefited from the inclusion of this plant at 5% of the diet in terms of production efficiency. Remarkably, another spin-off was found, namely that numbers of Campylobacter jejuni, a huge cause of food-borne infection in man, were also suppressed. Work is continuing on this material to identify the active ingredient. The plant has never before been used in animal feeding, herbal medicine or other traditional use. If its production, or the production of its key ingredient, can be scaled up, the plant could have important application across pig and poultry production.
Other interesting candidates were found for different applications too, particularly in ruminants. A number of plant materials suppressed intestinal parasites at some stage in their development. These plants included olive leaves. They were much less effective than chemical anthelmintics in vivo, however. Nevertheless, they should be investigated further for their efficacy in combination with each other, for example. The days of chemical anthelmintics are numbered and replacements will have to be found. Also in ruminants, dairy cows were fed stinging nettles (Urtica dioica) at up to 10% of their diet. The nettles had been found to stabilize ruminal pH, a vital factor in preserving a healthy fermentation. The results demonstrated clearly the benefits of nettles – the animals seemed to love them! The last application was to try to alter the composition of milk, cutting down saturated fatty acids and increasing concentrations of conjugated linoleic acid (CLA), which are believed to be beneficial to human health by preventing cancer and modulating inflammation. The ruminal bacteria responsible for the formation of CLA and others that remove CLA (‘biohydrogenation’) were targetted. Chrysanthemum coronarium inhibited the biohydrogenation process and thereby increased the CLA content of milk in sheep and cattle. Exactly how the C. coronarium achieved this is not yet clear. Other species of Chrysanthemum were ineffective, and not all batches of C. coronarium had the same efficacy. It appears that C. coronarium has an exceptionally high concentration of α-linoleic acid, which is known to be inhibitory to the formation of CLA from linoleic acid.
Many other plant materials, perhaps 7-8% of the total, had effects on one or more of the target areas. They were not considered further because they were considered less promising than the best candidates. We hope that others will take these observations forward and truly investigate their full potential.
The REPLACE project should be only a start.
Plants and their extracts and other natural alternatives to antimicrobials in feeds.
European Commission scientific officer: Jean Charles Cavitte
Project coordinator: Prof. R. John Wallace
Address: Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK