A research work performed by the Basque Technology Centre Neiker-Tecnalia has concluded that the naturally-occurring biopolymer known as chitosan is an effective option to growth-promoting antibiotics included in ruminant dietary formulations. The presence of these antibiotics as cattle feed additives is forbidden in the European Union since 2006, given that its use is related to the development of microbial antibiotic resistance.

The major drawback of this banning lies in the 3.5-5% increase in production costs in livestock farms besides the environmental constraints deriving from higher methane emissions. Therefore, research at Neiker-Tecnalia has focused on antimicrobial products, substituting growth-promoting antibiotics.

Chitosan turns out to be a highly promising option, because beyond its proven antimicrobial activity, it provides additional benefits since it is a biodegradable, biocompatible, renewable and non-toxic product. Antimicrobial activity specifically affects certain microorganisms in the rumen – the largest of the 4 pre-stomach chambers in ruminants – and thus there is a beneficial effect on ruminal digestion. The effect is similar to that of monensin, the most extended growth-promoting antibiotic in ruminant’s feed before the ban of these products.

Results were obtained from the simulation of ruminant fermentation in vitro tests followed by the Rumen Simulation Technique – RUSITEC and final animal testing. From now on, chitosan prospects in the modification of ruminal fermentation, with the aim of increasing feedstuffs efficiency and promoting nutrient utilisation by ruminants, need to be studied on a large scale. If the improvements entail production and commercial benefits, chitosan – a naturally occurring compound present in crustacean shells – appears as an effective substitutive to growth-promoting antibiotics in ruminant’s diet.