Antibiotic usage in pigs

Here the trends (2004 to 2012) in antibiotic use in pigs are discussed.

Sows and piglets

Figure 4.2 shows the trend in antibiotic use from 2004 to 2012: annual variation, with a strong decrease as from 2009, which seems to level off a bit in 2012.

Figure 4.2

Based on the first semester, the average use in sows/piglets is estimated to be 10 daily dosages per year in 2012 (95% Confidence Interval: 8-13 dd/ay). In 2009 the use was 25 daily dosages per year (95% CI: 21-30 dd/ay). The large confidence intervals are mainly caused by the large variation in use that exists between different farms. Seventy-five per cent of the antibiotics were orally administered, probably predominantly in piglets.

Figure 4.3 provides insight into the trends in the relative use of the various groups of antibiotics.

Figure 4.3

In 2012 31% of the total antibiotic use in sows/piglets consisted of tetracyclines, 36% of penicillins and another 17% of trimethoprim/sulfonamides.

Figure 4.4 shows the trends in the use of the antimicrobial classes defined as the most critically important in human medicine by the World Health Organization i.e. third- and fourth-generation cephalosporins, fluoroquinolones and macrolides. An important finding is that since 2009 the use of macrolides decreased substantially, and that in 2012 both the use of third- and fourth-generation cephalosporins and the use of fluoroquinolones in sows/piglets has dropped to zero.

Figure 4.4

Discussion

Within the sample, about 57% of the farms had an antibiotic use within the target level ('streefniveau') for 2012 of the Animal Drug Authority (SDa, 2012), 29% within the signalling level ('signaleringsniveau'), and 14% within the action level ('actieniveau').

In 2012, the use in sows/piglets was 10 daily dosages per animal year. However, in practice most antibiotics are likely used for the treatment of the piglets, and only incidentally for the sows. If it is assumed that 100% of the antibiotics are administered to the piglets, which have an average weight of 12.5 kg, this would mean that an average piglet is treated with antibiotics during 10 days in the period from birth to the age of 74 days (when the piglet weighs 25 kg and is delivered to the fattening farm).

Fattening pigs

Figure 4.5 shows the trend in antibiotic use from 2004 to 2012: increase until 2008, strong decrease from 2008 to 2012.
Figure 4.5

Based on the first semester, the average use in fattening pigs is estimated to be less than 6 daily dosages per year in 2012, of which 90% are orally administered (95% Confidence Interval: 4-7 dd/ay). In 2009 the average use was 16 daily dosages per year (CI: 11-20 dd/ay).

Figure 4.6 provides insight into the trends in the relative use of the various groups of antibiotics.

Figure 4.6

In 2012, 74% of the total antibiotic use in fattening pigs originated from the administration of tetracyclines and 10% from macrolides/lincosamides.

Figure 4.7 shows the trends in the use of the antimicrobial classes defined as the most critically important in human medicine by the World Health Organization, i.e. third- and fourth-generation cephalosporins, fluoroquinolones and macrolides. An important finding is that since 2009 the use of macrolides dropped substantially, and that in 2012 both third- and fourth-generation cephalosporins and fluoroquinolones were no longer applied.

Figure 4.7

Discussion

Within the sample about 69% of the farms had an antibiotic use within the target level ('streefniveau') for 2012 of the Animal Drug Authority (SDa, 2012), 11% within the signalling level ('signaleringsniveau'), and 20% fall into the action level ('actieniveau').

In 2012, the use in fattening pigs was approximately 6 daily dosages per animal year. Assuming a production period of 117 days, 2 daily dosages (= 6 x (117/365) are administered to each fattening pig during its production period from 25 kg to slaughter weight. This fattening pig has also received antibiotics at the breeding farm (during a maximum of 10 days), which brings the total exposure to antibiotics per fattening pig to approximately 12 days during its whole life from birth to slaughter at the age of 191 days.

If it is assumed that the average treatment weight of fattening pigs will be 30% lower than their average live weight - since younger animals are more likely to receive antibiotics than older animals - the estimation of the true exposure during the total lifetime increases from 12 days to a total of 13 days. Compared with 2009 this is a decrease of the total exposure of approximately 60%.

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