Table 1.

Number of samples and occurrence of S. aureus per farm. Overview of number of ewes sampled, number of Staphylococcus aureus isolates retrieved, number of ewes positive, number of ewes persistently colonized and number of ewes colonized in both teats, per farm

Farm	County	Size of farm	n of ewes sampled before grazing*	n isolates	n (%) number positive ewes before grazing	n of ewes sampled after grazing*	n isolates	n (%) number positive ewes after grazing	Total number of isolates	Total n ewes S. aureus positive	n persistent carriage	n ewes positive both teats spring and/or autumn
A*	X	301	161	14	13 (8.1%)	138	14	13 (9.4%)	31*	26	3	2
B	X	342	164	14	10 (6.1%)	153	21	17 (11.1%)	35	20	7	5
C	X	446	187	11	9 (4.8%)	173	14	13 (7.5%)	25	17	5	2
D	Y	274	95	4	3 (3.2%)	83	6	6 (7.2%)	10	7	2	1
Total			607	43	35 (5.8%)	547	55	49 (9.0%)	101	70	17	10

*An addition to sampling during spring and autumn, Farm A also provided samples from ewes with clinical mastitis during grazing (three samples from three different ewes). Overall, 31 isolates from Farm A

Size of farm = number of ewes with fetal counts