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133 danmap 2015 9. materials and methods the basic principles for the
dadd
are similar to the principles previously described for the add [danmap 2011, danmap 2012]. the
dadd
is based on the vetstat adds, but re-defined for each group of antimicrobial agents, adding adjustments for each combination of active compound, administration route, formulation, according to following principles: 1. a
dadd
group is defined for each antimicrobial agent by administration route and animal species; and when appro- priate also age group. 2. minor inconsistencies have been corrected e.g. due to rounding of
number
s,; 3. approved dosage for the most widely used antimicrobial products were given priority above dosage for products that are rarely used; 4. approved dosage for older products within the group were maintained as the common
dadd
even if a new product is approved with a higher dosage; 5. if the dosage for a group with large variation in approved dosages of the products, the dosages provided by ?the veterinary formulary? [british veterinary association, 2005, 6th edition] were applied; 6. dosages may vary within active compound and administra- tion route, if different dosages have been approved for different age group/indication or formulation. when principle 3 and 4 are conflicting, principle 5 is applied. denominator trends in antimicrobial consumption in pigs are presented in
dadd
per 1,000
animals
per day ? dapd. the
number
of ani- mals in a population (in epidemiological terms: the population at risk) is represented by their live biomass. the biomass of a species is calculated, taking into account average live body- weight and the average life-span in each age group. in 2015, dapd calculations were carried out for pigs only. due to a relative high
number
of pigs exported around 30 kg, an adjusted measure of consumption per pig was calculated. the adjustment is based on the assumption that pigs exported at 30 kg, on average, received the same amount of antimicrobi- al agents before export, as other pigs from farrowing to 30 kg. antimicrobial use per pig produced (adjusted) is calculated as: [
dadd
s +
dadd
w + (1+q)*
dadd
f] / (biomass-days-total + nw*5,800(kg*days)), where
dadd
s = amount of antimicro- bial agents used in sows;
dadd
w = amount of antimicrobial agents used in weaners;
dadd
f = amount of antimicrobial agents used in finishers; q is the proportion of weaning pigs exported around 30 kg. nw =
number
of pigs exported at 30 kg bodyweight, and nw*5,800 is the
number
of biomass days the exported pigs would have contributed to the live biomass if not exported. 9.2.2 estimation of live biomass of
animals
the estimation of live biomass and thus the
number
of stan- dard
animals
at risk per day depends on the available data sources for each species. pig production. the estimation was based on the
number
of pigs produced, including exports at different ages [statistics denmark; danish agriculture and food council], productivity data for each year [danish agriculture and food council] and census data for breeding
animals
[statistics denmark]. the average weight and life span for the growing
animals
(piglets, weaners and finishers) were estimated from the productivity
number
. the estimation methods were developed in coopera- tion with danish agriculture and food council. there are no statistics on average weight of breeding
animals
available, so dapd -
dadd
per 1,000
animals
per day the
number
of
dadd
s administered to an animal species during a year (in thousands) divided by the
number
of stan- dard
animals
at risk per day. the
number
of standard
animals
at risk per day takes into account species differences in average body-mass and life-span. when relevant, the
number
s of
dadd
s and standard
animals
at risk are estimated for specific age groups, or simply as
number
of doses (
dadd
s) used to treat one kg of animal divided with the total estimated biomass (in tonnes). dapd is a statistical measure, providing a rough estimate of the proportion of
animals
treated daily with an average maintenance dose of a particular antimicrobial agent. for example, 10 dapds indicate that an estimated 1% of the population, on average, receives a certain treatment on a given day. the dapd is also referred to as the treatment proportion. in principle, the metric dapd is parallel to the metric used in pharmaco-epidemiology for the human sec- tor, defined daily dose per 1,000 inhabitants per day (did), see section 9.2.3
dadd
defined animal daily dose
dadd
is the average maintenance dose per day for a drug used for its main indication in the appropriate animal species. the
dadd
is not defined at product level but for each antimicrobial agent, administration route and animal species and when appropriate, also age group.
dadd
has been specifically defined for use in danmap and does not always completely match the ?prescribed daily dose? or the recommended dosage in the summaries of product characteristics (spc).
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