Significance of interactions between Escherichia coli and respiratory pathogens in layer hen flocks suffering from colibacillosis-associated mortality

Figures & data

Table 1. HI log₂ titres against IBV and NDV of pooled sera collected with a 6-week interval from 20 flocks of layer hens with colibacillosis and from 20 control flocks

Antigen	Control flocks		Flocks with colibacillosis
	First sampling (minimum to maximum)	After 6 weeks (minimum to maximum)	First sampling (minimum to maximum)	after 6 weeks (minimum to maximum)
IB M41 (8 HA units)	8.4 (6 to 10)	8.6 (7 to 10)	8.6 (6 to 10)	8.5 (7 to 10)
IB D274 (8 HA units)	9.2 (7 to 11)	9.6 (8 to 11)	9.3 (8 to 11)	9.4 (8 to 11)
IB D1466 (8 HA units)	7.8 (6 to 9)	8.0 (6 to 9)	8.4 (6 to 10)	8.1 (6 to 9)
IB 4/91 (4 HA units)	7.6 (6 to 9)	8.2 (7 to 9)	7.9 (6 to 9)	8.2 (7 to 9)
NDV (8 HA units La Sota)	8.6 (7 to 11)	8.5 (7 to 10)	8.5 (6 to 11)	8.8 (6 to 11)

Table 2. Serology for the detection of antibodies or antibody titres against APV, M. gallisepticum, M. synoviae and O. rhinotracheale in sera collected at 2-week intervals from 20 flocks of layer hens with colibacillosis and from 20 control flocks

Pathogen	Test	Flocks	First sampling (minimum to maximum)	Second sampling (minimum to maximum)	Third sampling (minimum to maximum)	Fourth sampling (minimum to maximum)
APV	ELISA per cent reactors	Control	98.0 (75.0 to 100.0)	98.0 (80.0 to 100.0)	98.8 (85.0 to 100.0)	98.5 (85.0 to 100.0)
		Colibacillosis	95.5 (85.0 to 100.0)	95.8 (85.0 to 100.0)	94.8 (80.0 to 100.0)	94.5 (80.0 to 100.0)
M. synoviae^a	ELISA per cent reactors	Control	96.0 (40.0 to 100.0)	95.8 (45.0 to 100.0)	98.5 (80.0 to 100.0)	97.8 (80.0 to 100.0)
		Colibacillosis	86.3 (0.0 to 100.0)	88.1 (5.0 to 100.0)	92.1 (5.0 to 100.0)	93.9 (10.0 to 100.0)
O. rhinotracheale	ELISA titres	Control	9.1 (8.0 to 10.6)	8.8 (7.6 to 10.5)	9.1 (7.4 to 11.4)	9.0 (8.0 to 11.3)
		Colibacillosis	8.7 (7.3 to 9.8)	8.8 (6.9 to 10.6)	8.7 (7.2 to 10.1)	8.7 (7.4 to 9.8)
^a Slide agglutination and ELISA reactions for M. gallisepticum were all negative.

Table 3. Time of first sampling, outbreak characteristics and serological results of the colibacillosis-affected flocks

Flock code	Age at first sampling (weeks)	Interval from outbreak to first sampling (weeks)	Number of weeks with increased mortality	Flock sampled at first (1) or repeated (R) outbreak	Increase of titre or number of reactors against
1	21	0^a	3	1	–^b
2	22	2	4	1	M. synoviae
3	22	1	3	1	–
4	25	2	7	1	–
5	26	1	7	1	–
6	29	2	6	1	–
7	33	2	10	1	–
8	36	2	8	R	–
9	36	1	6	1	–
10	36	2	3	R	–
11	36	2	8	R	–
12	38	2	10	1	–
13	39	0	4	R	M. synoviae
14	48	2	3	R	–
15	53	0	4	R	O. rhinotracheale
16	53	2	3	R	–
17	54	1	4	R	–
18	59	2	4	R	–
19	61	2	10	R	–
20	87	2	3	R	–
^a Time interval of less than 1 week.
^b None.