When
avoparcin was prohibited for use as feed additive in poultry in Norway on 31 May 1995, an increased incidence of Clostridium perfringens-associated necrotic
enteritis (NE) and an increase in the use of antibacterial (AB)
drug therapy in meat-type poultry was expected. The consumption of AB drugs for use against NE in poultry in the period 1990-2001 was investigated by use of sales statistics at the
drug-wholesaler level. Defined daily dose (
DDD) per kg live weight poultry was the unit of measurement for
drug use (to correct for differences in the dosages). Sales figures of the AB drugs were converted to number of DDDpoultry sold for the numbers of broilers at risk (broilers were 97% of the slaughter poultry). Estimated annual percentages of the broilers treated against NE increased abruptly after the
avoparcin ban--but in 1996, this figure declined to the same level as before the ban and has remained at that low level since then. In November 1995,
narasin was approved temporarily as an
ionophore feed additive (IFA) in broilers. The usage patterns of IFAs in broilers were measured as the weight of feed to which an IFA was added per broiler chicken produced. In 1996-2001, the IFAs used in broilers were predominantly
narasin. We note that the temporary increase in NE after the
avoparcin ban coincide with the period before
narasin became available. The increase in the consumption of AB drugs for the treatment of NE in poultry following the
avoparcin ban has been negligible.