Evaluation of temporal surveillance system sensitivity and freedom from bovine viral diarrhea in Danish dairy herds using scenario tree modelling

Table 2 Herd parameters used in the simulation model by Foddai et al. [9]

Parameter	Value
Small herds (cows, heifers, calves)	ImpoCattle (24, 18, 2)^a, NoImpoCattle (1, 0, 0)^a
Medium herds (cows, heifers, calves)	ImpoCattle (180, 138, 10)^a, NoImpoCattle (123, 94, 6)^a
Large herds (cows, heifers, calves)	ImpoCattle (1070, 820, 66)^a, NoImpoCattle (1185, 908, 64)^a
Culling rate per year for cows	Pert distribution (min = 32 %, mode = 38 %, max = 43 %)^b
Culling rate per year for heifers	Pert (4, 7, 12 %)^b
Culling rate per year for calves	Pert (5, 12, 17 %)^b
Parity distribution (1^st, 2^nd, 3^rd and 4^th)	(31, 27, 22, and 20 %)^b
Percentage of dry cows	Pert (12, 17, 20 %)^b
Age in the heifers group (in days)	(700; 768; 870)^b
Days of inter-calving per cow between parity 1 and 2	(365, 399, 451)^b
Days of lactation per cow between parity 1 and 2	(305, 339, 391)^b
Days of inter-calving per cow after parity 2	(370, 391, 456)^b
Days of lactation per cow after parity 2	(310, 331, 396)^b

^a The median number of cows was set according to Danish data (2010), for herds with imports of cattle (ImpoCattle) and without (NoImpoCattle). According to a previous study [9], usually, Danish dairy herds have around 150 cows. In that case the number of heifers (animals with age between 61 and approximately 900 days) and calves (age up to 60 days) present in the herd corresponded to 76.7 % (115/150) and 5.4 % (8/150) of the number of cows. We used similar (approximated) heifers/cows and calves/cows ratios in the herd sizes of the two risk categories
^b Unchanged from Foddai et al. [9]

ISSN: 1746-6148