Scientific Opinion on the safety and efficacy of the product Cylactin (R) (Enterococcus faecium) as a feed additive for chickens for fattening EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP)

Cylactin (R) is a product consisting of viable cells of Enterococcus faecium. The product strain was found to be resistant to kanamycin. A detailed study of the nature of kanamycin resistance demonstrated the absence of known acquired genes coding for aminoglycosides- modifying enzymes. Two genetic determinants, the aminoglycoside acetyltransferase gene aac(6')-li and the gene sfkmr, both intrinsic to E. faecium, were shown to contribute to the resistance to kanamycin. In the view of the FEEDAP Panel, the resistance of this strain of E. faecium is most likely to be caused by an unknown mechanism that potentiates the effect of the sfkmr gene, and not by acquisition of resistance genes, and thus is not a cause for concern. When used at 100 times the recommended level, Cylactin r did not show any adverse effect on performance or mortality of chickens for fattening. Therefore, the additive is safe for the target animals at the proposed conditions of use. E. faecium NCIMB 10415 is free of known enterococcal virulence factors. No other concerns for consumer safety were identified. Cylactin r is not a skin/mucosal irritant or skin sensitiser. As the product is formulated with a large particle size and the dusting potential is low, inhalation exposure of users will be minimal. Cylactin r is efficacious in chickens for fattening as demonstrated in three trials showing an increase in final body weight when diets were supplemented at or close to the minimum recommended dose (0.3 x 10(9) CFU/kg feed). Cylactin r is compatible with decoquinate, monensin, robenidine, diclazuril and semduramycin.