Table 3 Serum antibody titer of Broiler GP (Grandparent) used in the experiment

A farm
Age of chicken^A	Flock 1		Flock 2		Flock 3		Flock 4
Age of chicken^A	Multinational ELISA kit^B	DomesticELISA kit^C	Multinational ELISA kit	DomesticELISA kit	Multinational ELISA kit	DomesticELISA kit	Multinational ELISA kit	DomesticELISA kit
48 weeks	6234	8610	3189	5917	3958	6977	2983	6437
60 weeks	4955	5985	4520	6564	2998	4830	3260	5360
Die out	8380	8467	5980	7464	4660	5851	5729	7459
B farm
Age of chicken	Flock 1		Flock 2		Flock 3		Flock 4
Age of chicken	Multinational ELISA kit	DomesticELISA kit	Multinational ELISA kit	DomesticELISA kit	Multinational ELISA kit	DomesticELISA kit	Multinational ELISA kit	DomesticELISA kit
22 weeks	3022	4304	3882	5350	2972	3948	3436	5486
26 weeks	3065	4169	3690	4555	3248	6377	6398	8326
30 weeks	2306	2195	2172	2280	2407	2616	5262	5219
33 weeks	4152	5600	1212	1967	2791	3628	5070	4660
36 weeks	5248	5875	2298	2408	3640	3604	4565	4999
39 weeks	3545	5143	6943	8281	7108	8343	4851	5516
42 weeks	3832	5534	4038	7096	5112	7182	3709	5882
45 weeks	5798	7815	5650	7477	11280	11280	3517	7072
C farm
Age of chicken	Flock 1		Flock 2		Flock 3		Flock 4
Age of chicken	Multinational ELISA kit	DomesticELISA kit	Multinational ELISA kit	DomesticELISA kit	Multinational ELISA kit	DomesticELISA kit	Multinational ELISA kit	DomesticELISA kit
1 week	4572	5470	6575	7736	3580	4931	4261	5394
3 weeks	147	55	95	30	81	24	302	585
5 weeks	273	877	673	2247	333	629	244	622
7 weeks	885	1411	1001	1648	692	1316	416	800
10 weeks	1382	2651	5184	7933	2490	6036	2391	3918

^AAge of chickens: The age of chicken when the samples were collected.
^BMultinational ELISA kit: ELISA titer of Infectious bronchitis virus antibodies in serum analyzed by a multinational corporation ELISA kit.
^C Domestic ELISA kit: ELISA titer of Infectious bronchitis virus antibodies in serum analyzed by a Domestic corporation ELISA kit.