TABLE 4.

Pattern of results in repeated PCR experiments on individual fecal DNA extracts from 30 bovine fecal samples that were culture positive but contained low numbers of viable M. avium subsp. paratuberculosis based on time to peak growth in Bactec medium (20)

Sample no.	Wks to GI of 999a	Experiment 1		Experiment 2
		Avg DNA quantity of positive replicates (pg)b	No. of positive replicatesc	Avg DNA quantity of positive replicates (pg)b	No. of positive replicatesc
1	6	0.0059	2		0
2	6		0		0
3	5		0		0
4	7	0.0037	4	0.0026	2
5	6	0.0023	3	0.0014	1
6	6	0.0032	4	0.0027	4
7	5	0.0062	4	0.0044	4
8	6		0	0.0042	1
9	7	0.0022	4	0.0029	3
10	12	0.0041	3	0.0041	1
11	7	0.0034	3	0.0020	2
12	6	0.0009	2		0
13	12	0.0051	4	0.0049	4
14	9	0.0043	4	0.0025	4
15	8	0.0041	2	0.0046	4
16	7	0.0048	4	0.0057	4
17	10		0		0
18	9	0.0028	3	0.0026	4
19	8	0.0040	4	0.0029	4
20	7		0		0
21	5	0.0011	4	0.0010	3
22	9		0		0
23	9	0.0026	4	0.0009	3
24	5	0.0019	4	0.0011	4
25	8	0.0025	4	0.0008	3
26	10	0.0016	3	0.0009	4
27	6	0.0214	4	0.0105	4
28	5	0.0051	4	0.0033	4
29	5	0.0062	4	0.0022	4
30	9	0.0022	4	0.0005	4

^aGI, growth index. Weeks of growth in radiometric liquid culture medium to reach a reading of 999.

^bNo average DNA quantity value is given for sample extracts for which zero replicates were positive.

^cThe number of replicates out of 4 that gave a positive result.