Table 1.

Summary of descriptive characteristics for three cattle cohorts from a beef herd in California which were followed up for Anaplasma marginale seroconversion.

Age group	Group 1 heifers	Group 2 heifers	Cows
Number sampled	40	66∗	37
Age on study day 0	9–12 months	15–17 months	>2 years
Study days sampled	77, 157	0, 70, 193	70, 157
Pastures during study	C (80 days)	A (70 days), B (123 days)	C (80 days)
Study months (2013)	May–August	March–September	May–August

^∗Sixty-six heifers were sampled on day 0. One heifer was lost to follow-up between day 0 and day 70 and a second heifer was lost to follow-up between day 70 and day 193. These heifers tested negative for A. marginale every time they were sampled.