Investigation of the Distribution of Salmonella within an Integrated Pig Breeding and Production Organisation in the United Kingdom

Table 5

Comparison of the length of time that a farm had kept pigs against isolation of Salmonella.

Salmonella isolates	Time that farm had been used for pigs (years)						Total farms
	5 or less	6–10	11–20	21–30	30+	Unknown
None	13 (26%)	12 (24%)	8 (16%)	14 (28%)	3 (6%)	0 (0%)	50
Any serovar	18 (16%)	16 (14%)	22 (20%)	30 (27%)	23 (21%)	2 (2%)	111
S. Typhimurium	12 (13%)	15 (16%)	19 (21%)	27 (29%)	18 (20%)	1 (1%)	91

Principal values are the number of study farms in each category. Values in parentheses are the percentage for that Salmonella isolation category.