Both at the fattening pig and the sow farms, NDDi
varied greatly between individual farms. In 2004 and
2005, some farms were able to raise pigs without applying
antibiotics (Table 2). On the other hand, maximum
NDDi values showed that there are farms that
are very intensive antibiotic users [e.g., the maximum
value of NDD2 in 2007 exceeded 365 implying that the
piglets received even more than 1 dosage per day (1.09
doses) over the entire period they were on the farm].
Consistently, the Lorentz curves also show that some
farms are “heavy users” as 20% of the farms use about
45% of the antibiotics, both on the fattening pig and
sow farms. The large between-farm variation in the use
of antibiotics in the Netherlands corresponds to values
reported from other countries, including Belgium (Timmerman
et al., 2006) and France (Chauvin et al., 2002).
Variations may be due to differences in hygiene status,
prophylactic use, and treatment decisions made by the
farmer or the veterinarian or both (Timmerman et al.,
2006).