Herd Category

N

Imported cattle

Imported doses of semen

Imported embryos

Truck visits

Hoof trimmer visits^{c}

PrP

EPI_{j}
^{d}


ImpoCattle

8

246 (10.6 %)

3776 (92.9 %)

5 (100 %)

5606 * 0.8 %^{b} = 45

A*B* 0.2 %

0.2 %

0.025 %

NoImpoCattle

4101

0

301020 (46.9 %)

272 (99.3 %)

5606 * 99.2 %^{b} = 5561

A*B* 99.8 %

99.8 %

0.024 %

Total

4109

246^{a}

304796^{a}

277 ^{a}

5606^{a}
 
100 %
 

N number of dairy herds delivering milk and tested in the fourth trimester of 2010 within each category, PrP proportion of herds within each category, EPIj effective probability of infection for each category “j”. Between brackets is the percentage of cattle, doses of semen and embryos imported from countries where BVD is endemic. We assumed that trucks and hoof trimmers went only to countries with endemic BVD status [12]

^{a,} From Foddai et al. [12]

^{b,} According to Foddai et al. [12], in total 5606 truck visits at risk occur in Danish dairy herds during a oneyear period. The estimated percentage of exports from the ImpoCattle and the NoImpoCattle category was 0.8 % and 99.2 %, respectively (Danish data 2010). We assumed that the number of trucks visits at risk in each category was proportional to the exports occurred from the category

^{c} The number of hoof trimmers visiting cattle herds abroad (A) during a oneyear period was a Pert distribution (5, 7, 18), while the number of times each hoof trimmer crosses the border (B) was Pert (1, 8, 30) (see Table 8 in [12]). The annual number of hoof trimmer visits, which could lead to BVDV introduction into each category, was assumed proportional to the herds present in the category and was estimated by: A * B * PrP_{ImpoCattle} and A * B * PrP_{NoImpoCattle}

^{d}The EPIj reported in the table was calculated using P_{H} 0.02 %. When we used P_{H} 0.2 % the EPIj was 0.20 for the ImpoCattle category and 0.19 % for the NoImpoCattle