Table 3.

Recovery of B. abortus strain 2308 from tissues obtained at necropsy after midgestational challenge from bison vaccinated with saline, Brucella abortus strain RB51 once by hand or pneumatic dart, or twice with RB51

Vaccination strategy	No. of tissues (mean ± SEM)a
	Maternal		Fetal
	Positive	Negative	Positive	Negative
Hand RB51b	9.2 ± 6.4 a	11.8 ± 6.4 a	4.0 ± 2.3 a	3.0 ± 2.3 a
Dart RB51c	11.0 ± 6.6 ab	10.0 ± 6.6 ab	3.4 ± 1.5 ab	3.6 ± 1.5 ab
Booster RB51d	5.8 ± 5.1 a	15.2 ± 5.1 a	3.4 ± 1.5a	3.6 ± 1.5 a
Control	17.4 ± 2.2 b	3.6 ± 2.2 b	6.6 ± 0.5b	0.4 ± 0.5 b

^aMeans with different letters are significantly different (P < 0.05).

^bThe vaccination dose was 1.1 × 10¹⁰ CFU.

^cThe vaccination dose was 2.2 × 10¹⁰ CFU.

^dThe initial vaccination dose was 1.1 × 10¹⁰ CFU, and the booster vaccination dose was 2.2 × 10¹⁰ CFU.