Table 2:

Characteristics of experimental animals

Animal #	Treatment	Age (days)*	Sex
12	M. ovipneumoniae	109	F (twin of 15)
19	M. ovipneumoniae	108	F
26	M. ovipneumoniae	105	M# (twin of 25)
30	M. ovipneumoniae	103	M#
15	PBS	109	M# (twin of 12)
17	PBS	109	M#
25	PBS	105	F (twin of 26)
27	PBS	104	F

^*age at time of infection;

^#all males were castrated at 11 weeks.