Table 1.

Numbers of pigs tested, sires, lines and families per farm¹

Source	1			2				3			4
Farm	A			B		D	E	C	F		G
Health status	SPF			SPF		Non-SPF		SPF	Non-SPF		Non-SPF
Generation	G1	G2	GX	G1	G2	G2	GX	G1	G2	GX	GX
No. pigs:
Performance	47	684	373	92	259	148	300	94	398	72	175
Immune traits	47	0	373	92	68	59	300	94	0	72	175
APP	0	0	373	0	0	0	300	0	0	72	175
No. groups:
Sires	21	42	27	23	5 2,3	5 2,3	17	10	52	11	55
Full-sib families	33	155	200	53	53	53	121	19	53	18	72
Genetic lines	8	4	2	1	1	1	1	1	1	8	13
Breed	LW	LW	LW	LW	LW	LW	LW	LW	LW	LR	LW

¹ For each source, G2 progeny were derived from G1 boars. All pigs tested for immune traits also had performance measurements. 2642 pigs were performance tested, 1280 pigs were tested for immune traits and 920 pigs were tested for APP. ² All sires were measured when they were growing pigs. ³These were the same sires.